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You’ve probably heard the news: Cicadas are coming. Or — wait — they’re already here.

And are they ever! Due to an unusual overlap of the lifecycles of two types (or broods) of cicadas, trillions of cicadas are expected to emerge in the US by the end of June, especially in the Midwest.

If you’d like to see where they’ve already arrived, track them here. And if you’re wondering if this cicada-palooza could help with grocery bills, read on to decide for yourself how appealing and how safe snacking on cicadas is for you. The pros and cons could change your outlook on the impending swarm.

What to know about cicadas

Don’t worry, cicadas are largely harmless to humans. In fact, their appearance is welcome in places where people routinely snack on them as a low-cost source of calories and protein.

Estimates suggest up to two billion people regularly eat insects, especially in South and Central America, Asia, Africa, Australia, and New Zealand. Cicadas, when available, are among the most popular. And if you thought no one in the US eats cicadas, check out this video from a May 2024 baseball game.

Are you tempted to eat cicadas?

For plenty of people, cicadas aren’t the food of choice. Some people can’t get past the idea of eating insects as food. That’s understandable: after all, the culture in which we are raised has a powerful influence on what we consider acceptable in our diets. Something some Americans might find off-putting (such as eating snakes) is common in China and Southeast Asia. Meanwhile, people outside the US find aspects of the typical Western diet unappealing (such as root beer, peanut butter and jelly, and processed cheese).

But some people shouldn’t eat cicadas because it could be dangerous for them.

Why you should — or shouldn’t — eat cicadas

Eating cicadas is common in many parts of the world because they are

• nutritious: cicadas are low in fat and high in protein, including multiple essential amino acids
• inexpensive or free
• tasty (or so I’m told): descriptions of their flavor vary from nutty to citrusy to smoky and slightly crunchy.

In years when cicadas emerge, recipes for dishes containing cicadas emerge as well.

Then again, there are several good reasons to avoid making cicadas a part of your diet, including these:

• You just can’t get past the “ick” factor. Adventurous eaters may be willing to try or even embrace consuming cicadas, while others will be unable to view the idea as anything other than horrifying.
• You find the taste or consistency unappealing.
• You’re “cicada intolerant.” Some people get stomach upset, nausea, or diarrhea if they eat too many cicadas.
• You’re pregnant or breastfeeding, or are a young child. Concerns about even low levels of pesticides or other toxins in cicadas have led to recommendations that these groups not eat them. Doesn’t this suggest the rest of us should also steer clear? Well, thus far, at least, there’s no evidence that toxins in cicadas are causing health problems.

But there is one more very important entry on this list: people with a shellfish allergy should not eat cicadas. Odd, right?

The shellfish-cicada connection

Cicadas are biologically related to lobsters, shrimp, crabs, and other shellfish. So if you’re allergic to shellfish, you might also be allergic to cicadas. A particular protein called tropomyosin is responsible for the allergy. It’s found in shellfish as well as in many insects, including cicadas.

The allergic reaction occurs after eating the cicada. Just being around them or handling them won’t trigger a reaction.

Among people with a shellfish allergy, developing a reaction after eating cicadas could be a bigger problem than it seems: up to 10% of people have shellfish allergies and, as noted, insect consumption is common worldwide.

Is it okay for your dog or cat to eat cicadas?

Walking your dog after the emergence of cicadas can be a new and exciting experience for you and your pet! Dogs may chase after cicadas and eat them. Cats might, too, if given the chance. That can be a problem if your pet eats too many, as some will experience stomach upset or other digestive problems.

While the insects are considered harmless to dogs, the American Kennel Club says it’s best to steer them away from cicadas once they’ve eaten a few.

Which other insects trigger allergies?

While insect-related allergic reactions (think bee stings) and infections (like Lyme disease) are well known, the insect-food-allergy connection is a more recent discovery.

One recently recognized condition is the alpha-gal syndrome, in which a person bitten by certain ticks develops an allergy to meat. The name comes from a sugar called galactose-α-1,3-galactose (or alpha-gal) found in many types of meat including beef, lamb, pork, and rabbit. According to the CDC, up to 450,000 people in the US may have developed this condition since 2010.

There aren’t many rigorous studies of the overlap of insects and food allergies, so there are probably others awaiting discovery.

The bottom line

When it comes to eating cicadas, I’ll pass. It’s not because of the risks. I’ve never had a problem with shellfish, and for most people the health risks of eating cicadas seem quite small. It’s just unappealing to me, and I’m not a particularly adventurous eater.

But let’s go easy on those who do enjoy snacking on cicadas. Insects offer a good source of calories and protein. Just because eating them seems unusual in the US doesn’t make it wrong.

So, if you like to eat cicadas and have no shellfish allergy or other reason to avoid them, go for it! This may be a very good summer for you.

About the Author

Robert H. Shmerling, MD, Senior Faculty Editor, Harvard Health Publishing; Editorial Advisory Board Member, Harvard Health Publishing

Dr. Robert H. Shmerling is the former clinical chief of the division of rheumatology at Beth Israel Deaconess Medical Center (BIDMC), and is a current member of the corresponding faculty in medicine at Harvard Medical School. … See Full Bio View all posts by Robert H. Shmerling, MD

If you spend time outdoors — which we all should do, for all sorts of reasons — you are likely to encounter biting bugs. Most of the time the bites are just a nuisance. But besides the fact that sometimes they can be painful or itchy, bug bites can lead to illness — like Lyme disease from ticks, or Zika, malaria, or West Nile disease from mosquitoes. So preventing bites is a good idea for all of us, and certainly for children.

Simple precautions will help

Before talking about insect repellents, it’s important to remember that there are simple and effective precautions, nearly all of which don’t involve any chemicals. For example:

• Empty out any standing water outside your home. That’s where mosquitoes breed.
• Wear long-sleeved shirts and long pants if you are going to be in areas with lots of biting insects. If you treat clothes (and shoes and gear) with 0.5% permethrin, it can be helpful.
• Be aware that mosquitoes are most likely to be out at dusk and dawn, and plan activities accordingly.
• To avoid tick bites, avoid wooded and brushy areas and keep to the center of paths when you hike. Be sure to do a tick check when you come home — not just of all the people in your group, but also any pets or gear that came along. Taking a shower soon after arriving home can help with both tick checks and washing off any unattached ticks.

Make choices about insect repellent

Insect repellents can be very useful. Some are more effective than others, and some can have side effects, so it’s important to do your homework. The Environmental Protection Agency has a great interactive tool that can help you choose the best repellent for your particular situation.

The most effective repellent is DEET (N, N-diethyl-meta-toluamide). It works against both mosquitoes and ticks, and is definitely the go-to repellent if you really want or need to prevent bites. The higher the concentration, the longer it lasts: 10% will give you about two hours of coverage, while 30% can protect you for about five hours. The American Academy of Pediatrics (AAP) recommends not using more than 30% on kids, and not using any repellents on infants less than 2 months old.

The most common side effect is skin irritation, and if you ingest it (you never know with little kids) it can lead to nausea and vomiting. Eye irritation is possible, which is why you should never spray any repellent directly to the face, but rather put it on your hands and then carefully apply to the face. In very rare cases, like one in every 100 million users, DEET can lead to brain problems such as seizures if used in high doses. This is an incredibly rare side effect, and not something that should stop you from using it, especially if you are in an area with a lot of ticks, or an area with lots of disease-carrying mosquitoes.

Here are some alternatives with minimal to no side effects (eye irritation most common; avoid as noted above):

• oil of lemon eucalyptus, or PMD (the manmade alternative). This works nearly as well as DEET.
• picaridin, which works better against mosquitoes than ticks
• 2-undecanone
• IR-3535, the active ingredient in Avon products, although it is not very effective
• citronella, although it is even less effective.

Applying insect repellent — and sunscreen

Whatever you use, follow label directions and be sure that you are careful as you apply it to all exposed skin. It’s best to spray in an open area — and spray clothing too. Pump bottles and wipes with insect repellent may help you apply products carefully. Try to choose the best product for your situation so that you can apply it just once; the EPA tool is great for that. Don’t forget sunscreen; apply that first so your skin can absorb it.

The Centers for Disease Control and Prevention (CDC) has more information about applying insect repellent on children and preventing bites from mosquitoes and ticks.

Also visit the Harvard Health Publishing Lyme Wellness Initiative to learn about preventing –– or living with –– Lyme disease and other tick-borne illnesses.

About the Author

Claire McCarthy, MD, Senior Faculty Editor, Harvard Health Publishing

Claire McCarthy, MD, is a primary care pediatrician at Boston Children’s Hospital, and an assistant professor of pediatrics at Harvard Medical School. In addition to being a senior faculty editor for Harvard Health Publishing, Dr. McCarthy … See Full Bio View all posts by Claire McCarthy, MD

Animals renowned for their outstanding night vision include owls, cats, tarsiers (a tiny primate in Southeast Asia) — and even the dung beetle.

But humans? Not so much.

Over time, many people suffer from night blindness, also known as nyctalopia. This condition makes seeing in dim or dark settings difficult because your eyes cannot adjust to changes in brightness or detect light.

What are the dangers for those experiencing night blindness?

Night blindness is especially problematic and dangerous when driving. Your eyes cannot adjust between darkness and the headlights of oncoming vehicles, other cars may appear out of focus, and your depth perception becomes impaired, which makes it difficult to judge distances.

Night blindness also may affect your sight at home by making it hard for your vision to quickly adjust to a dark room after turning off the lights. “This can cause people to bump into furniture or trip and suffer an injury,” says Dr. Isabel Deakins, an optometrist with Harvard-affiliated Massachusetts Eye and Ear.

What happens in the eye to create night blindness?

The ability to see in low-light conditions involves two structures in the eye: the retina and the iris.

The retina, located in the back of the eye, contains two types of light-detecting cells called cones and rods. The cones handle color vision and fine details while the rods manage vision in dim light.

The iris is the colored part of your eye. It contains muscles that widen or narrow the opening of your pupil to adjust how much light can enter your eyes.

If your irises don’t properly react, the pupils can dilate and let in too much light, which causes light sensitivity and makes it hard to see in bright light. Or your pupils may remain too small and not allow in enough light, making it tough to see in low light.

What causes night blindness?

Night blindness is not a disease but a symptom of other conditions. “It’s like having a bruise on your body. Something else causes it,” says Dr. Deakins.

Several conditions can cause night blindness. For instance, medications, such as antidepressants, antihistamines, and antipsychotics, can affect pupil size and how much light enters the eye.

Eye conditions that can cause night blindness include:

• glaucoma, a disease that damages the eye’s optic nerves and blood vessels
• cataracts, cloudy areas in the lens that distort or block the passage of light through the lens
• dry eye syndrome.

However, one issue that raises the risk of night blindness that you can’t control is age. “Our eyes react more slowly to light changes as we age, and vision naturally declines over time,” says Dr. Deakins.  “The number of rods in our eyes diminish, pupils get smaller, and the muscles of the irises weaken.”

What helps if you have night blindness?

If you notice any signs of night blindness, avoid driving and get checked by an eye care specialist like an optometrist or ophthalmologist. An eye exam can determine if your eyeglass prescription needs to be updated.

“Often, a prescription change is enough to reduce glare when driving at night," says Dr. Deakins. “You may even need separate glasses with a stronger eye prescription that you wear only when driving at night.”

Adding an anti-reflective coating to your lens may help to cut down on the glare of the headlights of an oncoming car. However, skip the over-the-counter polarized driving glasses sold at many drug stores. "These may help cut down on glare, but they don't address the causes of night blindness," says Dr. Deakins.

An eye exam also will identify glaucoma or cataracts, which can be treated. Glaucoma treatments include eyedrops, laser treatment, or surgery. Cataracts are corrected with surgery to replace the clouded lens with an artificial one. Your eye care specialist can also help identify dry eye and recommend treatment.

Ask your primary care clinician or a pharmacist if any medications that you take may cause night blindness. If so, it may be possible to adjust the dose or switch to another drug.

Three more ways to make night driving safer

You also can take steps to make night driving safer. For example:

• Wash the lenses of your glasses regularly. And take them to an optician to buff out minor scratches.
• Keep both sides of your front and rear car windshields clean so that you can see as clearly as possible.
• Dim your dashboard lights, which cause glare, and use the night setting on your rearview mirror.

About the Author

Matthew Solan, Executive Editor, Harvard Men's Health Watch

Matthew Solan is the executive editor of Harvard Men’s Health Watch. He previously served as executive editor for UCLA Health’s Healthy Years and as a contributor to Duke Medicine’s Health News and Weill Cornell Medical College’s … See Full Bio View all posts by Matthew Solan

About the Reviewer

Howard E. LeWine, MD, Chief Medical Editor, Harvard Health Publishing

Dr. Howard LeWine is a practicing internist at Brigham and Women’s Hospital in Boston, Chief Medical Editor at Harvard Health Publishing, and editor in chief of Harvard Men’s Health Watch. See Full Bio View all posts by Howard E. LeWine, MD

When cancer patients are treated with radiation, it’s possible that the therapy itself may cause new tumors to form in the body later. Radiation kills cancer cells by damaging their DNA, but if the treatments cause genetic damage to normal cells near the radiation target, there’s a small risk that these secondary malignancies may arise over time.

Just over 10 years ago, Canadian researchers set out to assess the risk of secondary malignancy among men with prostate cancer who were treated with a type of radiation called brachytherapy. Unlike radiation delivered from sources outside the body, brachytherapy is accomplished by implanting dozens of radioactive pellets, or “seeds,” directly into the tumor site. Those seeds, which are never removed, emit radiation at a dose that declines toward zero over the course of a year.

Brachytherapy has the advantage of convenience. Instead of traveling for repeat sessions of radiation, men need only one treatment, usually given in an outpatient setting. But brachytherapy is also falling out of favor, in part because newer types of external beam radiation deliver high-precision doses with fewer side effects.

Study methodology and results

The Canadian study compared rates of secondary malignancies in the pelvis among men treated either with brachytherapy or with surgery to remove the prostate. All the treatments took place in British Columbia between 1998 and 2000. The brachytherapy group included 2,418 men with an average age of 66, while the surgically-treated group contained 4,015 men whose average age was 62. Within that group, 2,643 men had been treated with surgery alone, and 1,372 men with surgery plus external beam radiation given later.

After median follow-ups of between 5.8 years (brachytherapy) and 6.4 years (surgery), the study team reported in 2014 that there was no difference in rates of secondary malignancies between the groups, or with cancer incidence in the general population.

But that’s no longer the case: In April 2024, the researchers published updated findings. This time, rates of new cancers in the pelvis — including the bladder and rectum — were higher in the brachytherapy group. Specifically, 6.4% of brachytherapy-treated men had secondary malignancies at 15 years of follow-up, increasing to 9.8% after 20 years. By contrast, 3.2% and 4.2% of surgically-treated men developed secondary pelvic malignancies over the same durations. There was no difference in deaths from secondary malignancies between the groups.

The strength of the association with bladder cancer in particular is “similar to that seen with smoking,” wrote the author of an accompanying editorial. Results from the study “should be considered when treating men with localized prostate cancer who have a long life expectancy,” the authors concluded.

Commentary from experts

“I do believe that this study reveals a dark truth about radiation for prostate cancer that has been long suspected,” says Dr. Anthony Zietman, a professor of radiation oncology at Harvard Medical School and Massachusetts General Hospital, and a member of the advisory and editorial board for the Harvard Medical School Guide to Prostate Diseases. “As the decades pass after radiation therapy of any kind — brachytherapy or external beam — the risk for radiation-induced malignancies rises.

“These malignancies are usually in adjacent organs like the bladder and rectum, or within the prostate itself. They may be very curable, and thus the survival rates are the same for radiation or surgically treated patients, but there is little doubt that, for these patients, they represent a ‘sting in the tail’ long after the radiation has been given and forgotten. This data certainly gives us pause when offering radiation to very young men with several decades of life expectancy ahead of them, and it also reminds us of the value of follow-up visits.”

“The fact that second cancers arise in the area where radiation was given is not surprising, but the magnitude of the long-term increases is concerning,” added Dr. Marc Garnick, the Gorman Brothers Professor of Medicine at Harvard Medical School and Beth Israel Deaconess Medical Center, and editor in chief of the Harvard Medical School Guide to Prostate Diseases. “There are other common and troublesome urinary side effects of brachytherapy — independent of second cancers — that patients should fully consider before selecting it as a treatment option. This is especially true given the availability of other convenient and similarly effective prostate cancer therapies.”

About the Author

Charlie Schmidt, Editor, Harvard Medical School Annual Report on Prostate Diseases

Charlie Schmidt is an award-winning freelance science writer based in Portland, Maine. In addition to writing for Harvard Health Publishing, Charlie has written for Science magazine, the Journal of the National Cancer Institute, Environmental Health Perspectives, … See Full Bio View all posts by Charlie Schmidt

About the Reviewer

Marc B. Garnick, MD, Editor in Chief, Harvard Medical School Annual Report on Prostate Diseases; Editorial Advisory Board Member, Harvard Health Publishing

Dr. Marc B. Garnick is an internationally renowned expert in medical oncology and urologic cancer. A clinical professor of medicine at Harvard Medical School, he also maintains an active clinical practice at Beth Israel Deaconess Medical … See Full Bio View all posts by Marc B. Garnick, MD

When you live in a coastal area, preparing early for potential hurricanes is a must. Storms can develop quickly, leaving little time to figure out where you’ll be safe or which items to pack if you have to evacuate. And health care necessities, such as medications or medical equipment, are often overlooked in the scramble.

“People might bring their diabetes medication but forget their blood sugar monitor, or bring their hearing aids but forget extra batteries for them,” says Dr. Scott Goldberg, medical director of emergency preparedness at Brigham and Women’s Hospital and a longtime member of a FEMA task force that responds to hurricane-damaged areas.

Here’s some insight on what to expect this hurricane season, and how to prioritize health care in your hurricane kit.

What will the 2024 hurricane season look like?

This year’s hurricane predictions underscore the urgency to start preparations now.

Forecasters with the National Oceanic and Atmospheric Administration’s National Weather Service expect above-normal activity for the 2024 hurricane season (which lasts until November 30).

Meteorologists anticipate 17 to 25 storms with winds of 39 mph or higher, including eight to 13 hurricanes — four to seven of which could be major hurricanes with 111 mph winds or higher.

What kinds of plans should you make?

Preparing for the possibility of big storms is a major undertaking. Long before ferocious winds and torrential rains arrive, you must gather hurricane supplies, figure out how to secure your home, and determine where to go if you need to evacuate (especially if you live in a flood zone). Contact the emergency management department at your city or county for shelter information.

If you’ll need help evacuating due to a medical condition, or if you’ll need medical assistance at a shelter, find out if your county or city has a special needs registry like this one in Florida. Signing up will enable first responders to notify you about storms and transport you to a special shelter that has medical staff, hospital cots, and possibly oxygen tanks.

What should you pack?

While a shelter provides a safe place to ride out a storm, including bathrooms, water, and basic meals, it’s up to you to bring everything else. It’s essential to pack medical equipment and sufficient medications and health supplies.

“It’s natural to just grab the prescription medications in your medicine cabinet, but what if it’s only a two-day supply? It might be a while before you can get a refill. We recommend at least a 14-day or 30-day supply of every prescription,” Dr. Goldberg says. “Talk to your doctor about the possibility of getting an extra refill to keep on standby for your go bag.”

Other health-related items you’ll want to pack include:

• medical supplies you use regularly, such as a blood pressure monitor, heart monitor, CPAP machine, wheelchair, or walker
• over-the-counter medicines you use regularly, such as heartburn medicine or pain relievers
• foods for specific dietary needs, such as gluten-free food if you have celiac disease (if you have infants or children, you’ll need to bring foods they can eat)
• healthy, nonperishable snacks such as nuts, nut butters, trail mix, dried fruit, granola bars, protein bars, and whole-grain bread, crackers, or cereals
• hygiene products such as soap, hand sanitizer, toothbrushes and toothpaste, shampoo, deodorant, infant or adult diapers, lip balm, moist towelettes, and toilet paper — because shelters often run out of it.

Remember the basics

In some ways, you can think of shelter living like camping. You’ll need lots of basic supplies to get through it, including:

• a sleeping bag or blanket and pillow for each person in your family
• clean towels and washcloths
• a few extra changes of clothes per person
• a first-aid kit
• flashlights and extra batteries
• chargers for your electronic gadgets
• rechargeable battery packs.

Bring important paperwork

In addition to supplies, bring important documents such as:

• a list of your medications, vitamins, and supplements (include the name, dose, and frequency of each one)
• a list of the names, addresses, and phone numbers of your primary care provider and any specialists who treat you
• a list of your emergency contacts and their phone numbers
• your pharmacy’s phone number and address
• copies of your birth certificate and driver’s license
• copies of home, car, or life insurance policies
• copies of your health insurance cards
• a copy of your advance directive — which includes your living will and health care proxy form.

“Store these documents on a flash drive. Also make photocopies of them, which are easiest for doctors to consult in an emergency setting. Place them in a plastic zip-top bag to keep them dry,” Dr. Goldberg advises.

Prepare right now

Start today. Gather as many go-bag supplies as you can, including the bags. A small suitcase, backpack, or duffel bag for each person in your family will work well.

And try not to put off these important preparations. “Hurricanes are major stressors. You might be worried, sleep deprived, fatigued, and emotional,” Dr. Goldberg says. “All of that will make it hard to think clearly. You’ll do yourself and your family a favor by having discussions now and getting started on your hurricane plan.”

About the Author

Heidi Godman, Executive Editor, Harvard Health Letter

Heidi Godman is the executive editor of the Harvard Health Letter. Before coming to the Health Letter, she was an award-winning television news anchor and medical reporter for 25 years. Heidi was named a journalism fellow … See Full Bio View all posts by Heidi Godman

About the Reviewer

Howard E. LeWine, MD, Chief Medical Editor, Harvard Health Publishing

Dr. Howard LeWine is a practicing internist at Brigham and Women’s Hospital in Boston, Chief Medical Editor at Harvard Health Publishing, and editor in chief of Harvard Men’s Health Watch. See Full Bio View all posts by Howard E. LeWine, MD

Drug side effects are common, and often quite troublesome.

Major side effects, such as severe or even life-threatening allergic reactions, require immediate treatment and discontinuation of the drug. More minor symptoms may be tolerable when weighed against drug benefits. And sometimes, these go away on their own as the body gets used to the drug.

But there’s another type of side effect you hear much less about: ones that are beneficial. Though uncommon, they’re worth keeping in mind when you’re starting a new medicine.

Aren’t all side effects bad?

The term side effect is usually assumed to be a bad thing. And that’s typically true. But that leaves out the “good” side effects. Relatively little is published on this, so it’s not clear how common they are. But four notable examples include:

• Minoxidil (Rogaine, Gainextra, other brands). Developed in the 1970s for high blood pressure, this drug also increased hair growth in study subjects. What was initially considered a bothersome side effect eventually became its primary use: topical forms of this drug are commonly used to treat hair loss.
• Diphenhydramine (Benadryl or generic versions). This common treatment for allergic conditions has the side effect of drowsiness. For adults with allergy issues and trouble sleeping, the sedative effect can be helpful. Regular, long-term use of diphenhydramine is not recommended, as it may increase the risk of dementia.
• Sildenafil (Viagra or generic versions). Originally developed as a treatment for high blood pressure and angina, it didn’t take long for male users to realize the drug could trigger erections within 30 to 60 minutes. The makers of sildenafil recognized that under the right circumstances, this could be a highly beneficial side effect. In 1998 it was approved as a treatment for erectile dysfunction.
• Semaglutide (Ozempic, Wegovy, Rybelsus). This drug was developed to treat diabetes, but early users noticed reduced appetite and significant weight loss. Now, several formulations of these related drugs are approved for diabetes and/or weight loss.

In the best study I’ve read on the topic, researchers found more than 450 reports of serendipitous beneficial effects of various drugs since 1991. And that may be an underestimation, since report forms did not specifically ask for or label this type of side effect, according to the study authors.

Silver linings: Repurposing and repackaging drugs

While the discovery of helpful drugs can arise unexpectedly, drug developers are increasingly using a more intentional approach: using side effect profiles to look for new uses.

For example:

• A drug reported to cause reduced sweating as a side effect may be effective for hyperhidrosis, a condition marked by excessive sweating.
• Drugs reported to cause low blood pressure as a side effect might be effective treatments for high blood pressure (hypertension).
• New treatments for breast cancer may include older medicines that have a similar side effect profile as known anti-cancer drugs.

The availability of large side effect registries has made this method of identifying drugs for repurposing a more realistic option. So, even negative side effects can have a silver lining.

Bad side effects and the nocebo effect

While side effects can be positive, most are not. Medication side effects are a common reason people give for not taking prescribed drugs regularly. And adverse reactions to medicines prompt up to 8% of hospital admissions, according to one analysis.

To make matters worse, in some cases the expectation of side effects seems to make them more likely to occur. Called the nocebo effect, it increases the chances of experiencing a negative side effect and seems due, at least in part, to expectations. Contrast this with the placebo effect, where a sugar pill or another inactive treatment can lead to benefit.

The bottom line

Many people avoid taking medications because they fear possible side effects. That’s understandable. But not taking a medication can mean missing out on its benefits. And anticipation or expectation of side effects can increase the chances you’ll have them.

So, while it’s important to be aware of the most common side effects caused by the medicines you take, it’s also important not to overestimate your chances of experiencing them. And remember: there’s always a chance you’ll have a side effect you actually welcome.

About the Author

Robert H. Shmerling, MD, Senior Faculty Editor, Harvard Health Publishing; Editorial Advisory Board Member, Harvard Health Publishing

Dr. Robert H. Shmerling is the former clinical chief of the division of rheumatology at Beth Israel Deaconess Medical Center (BIDMC), and is a current member of the corresponding faculty in medicine at Harvard Medical School. … See Full Bio View all posts by Robert H. Shmerling, MD

Pop quiz: what is Salmonella? If you’ve ever had a run-in with this bacteria, you know it can cause a food-borne illness called salmonellosis, a form of food poisoning. But you may not know that Salmonella bacteria sicken an estimated 1.35 million people and hospitalize 26,500 every year in the United States. What’s more, it kills more total people than any other type of food poisoning.

And Salmonella bacteria can be sneaky — not only by triggering unusual complications, but infecting people in startling ways, says Dr. Elizabeth Hohmann, an infectious disease specialist at Massachusetts General Hospital. One patient she treated showed up with an abdominal aortic aneurysm — a dangerous bulge in the lower section of the body’s largest artery — that looked infected. Testing revealed a culprit some would find surprising: Salmonella.

“It’s just an interesting organism and it can be kind of scary,” she says.

How do people get infected by Salmonella?

Many of the foods Salmonella bacteria lurk in are raw or undercooked. Breaded raw chicken products like nuggets and chicken Kiev are one way it may reach your table. But a variety of foods have been implicated — including organic basil, cantaloupes, ground beef, nut butters, raw cookie dough, eggs, raw or unpasteurized milk, and flour.

Even small pets such as turtles and frogs, along with dog food, have contributed to Salmonella outbreaks in recent years.

You can also become infected by handling contaminated food and spreading the bacteria from your hands to your mouth. Additionally, you can spread it to others on your hands or even on your clothes without becoming sick yourself.

“It’s a bug that’s carried in stool and animal feces and is also present in the environment,” Dr. Hohmann says. “So it can set up shop in lots of different inanimate objects, soils, and machinery, especially in moist environments.”

What symptoms can Salmonella cause?

Most of the time, Salmonella infection leads to gastroenteritis, usually causing just an upset stomach, abdominal cramps, and diarrhea. These symptoms can start as soon as six hours after ingesting the bacteria. Typically, symptoms resolve on their own within two to three days.

Some people have such mild symptoms they’re barely noticeable. “The classic case might be a college student who eats a burrito from a sketchy place, gets sick for a couple of days, gets better, and doesn’t think anything of it,” says Dr. Hohmann.

Sometimes symptoms are more serious, such as severe abdominal cramping and bloody diarrhea, or unexplained high fever and marked fatigue. These symptoms require a call to your doctor.

How is salmonellosis treated?

Most people will get better on their own without any medicines. Replacing lost fluids by sipping water or electrolyte drinks to avoid dehydration will help.

Call a doctor if you have

• diarrhea and a fever higher than 102° F
• diarrhea that doesn’t improve after three days
• bloody stools
• vomiting so severe it prevents you from keeping liquids down.

Treating the infection with medicine comes with an annoying paradox, Dr. Hohmann says. If doctors decide to prescribe antibiotics, the person taking the medicine may shed the organism for longer than if they were never treated. “Then that person may have the opportunity — either through poor personal hygiene, sex, or working as a food worker — to spread it to others,” she explains. “It’s challenging.”

What complications can Salmonella lead to?

Some people get sicker with salmonellosis than others, with seemingly no rhyme or reason. But certain folks are especially vulnerable to serious infection, including:

• adults 65 and older
• pregnant women
• children under 5
• people whose immune systems are weakened by diseases (such as cancer) or treatments (such as immunosuppressing drugs).

A small percentage of those infected can have Salmonella in their blood, which can spread the infection to other parts of the body such as the urinary tract, bones, joints, or central nervous system (brain and spinal fluid).

And, like Dr. Hohmann’s patient with the abdominal aortic aneurysm, on rare occasions Salmonella can lead to unusual blood vessel complications in people who already have atherosclerosis, blockage of the arteries caused by plaque buildup.

“It’s not that common,” she says. “Many physicians are aware of it, so they take special care if Salmonella is found in a person with vascular disease.”

What steps can you take to avoid Salmonella?

While new USDA rules that take effect in 2025 may help fuel recalls of certain foods, we all can take steps to avoid the food poisoning, illness, and hospitalizations that Salmonella exposure can cause.

Dr. Hohmann and the CDC suggest these strategies:

• Using hot water and soap, wash cutting boards or plates on which you cut into raw foods — including vegetables and fruit — before using those surfaces for other purposes. If possible, use separate cutting boards for produce, meat, and fish.
• Refrigerate or freeze foods that are perishable, prepared, or left over within two hours to thwart salmonella growth.
• Always wash hands well with soap and water before preparing food and after contact with animals, using the toilet, or changing diapers.
• If you have a sick pet, take extra care handling its feces and wash your hands thoroughly afterward.

Take additional steps to help more vulnerable people stay healthy:

• Don’t let young children touch high-risk animals, such as turtles, frogs, chickens, or ducks. “And if you’re taking young children to a petting zoo, they should not be petting animals unless you can disinfect their hands immediately afterward,” she says.
• Older adults and those with compromised immune systems should take extra care to wash and cook foods thoroughly.
• People who have had a transplant (such as a kidney transplant) should not keep reptiles or amphibians as pets.

“You hate to make people paranoid, so that we’re washing our lettuce leaves with soap, but it’s worth thinking about these things, particularly if you have people in your household who are susceptible — which is an increasing number of people,” Dr. Hohmann says.

About the Author

Maureen Salamon, Executive Editor, Harvard Women's Health Watch

Maureen Salamon is executive editor of Harvard Women’s Health Watch. She began her career as a newspaper reporter and later covered health and medicine for a wide variety of websites, magazines, and hospitals. Her work has … See Full Bio View all posts by Maureen Salamon

About the Reviewer

Howard E. LeWine, MD, Chief Medical Editor, Harvard Health Publishing

Dr. Howard LeWine is a practicing internist at Brigham and Women’s Hospital in Boston, Chief Medical Editor at Harvard Health Publishing, and editor in chief of Harvard Men’s Health Watch. See Full Bio View all posts by Howard E. LeWine, MD

It’s undeniable: modern medicine offers ever-expanding ways to heal and prevent disease. But it’s also true that health care can cause harm. One analysis found that about 6% of health care encounters caused preventable harm, leading to thousands of deaths each year. And it’s not just errors that cause trouble. Highly skilled health care providers can cause harm even when they do everything right.

So, how can you reduce your chances of being harmed? Understanding what you can do to lessen the possibility of harm and what’s beyond your control are good first steps.

Whatever happened to “first do no harm”?

Fortunately, it remains a central tenet of medical care. Yet our health care system is complex and fragmented. Each year new medications are added to an ever-growing list, and people live longer with more chronic medical conditions than happened in the past. So in one sense, the successes of modern medical care may contribute to the high rate of health care–related harm.

These harms are often due to our complicated system of health care rather than one individual’s mistake. Harm due to substandard or negligent care is known as medical malpractice. Both health care providers and health care systems have important roles to play in preventing harm to patients.

Are there harms that cannot be prevented?

An enormous volume of scientific research teaches the best ways to diagnose, treat, and prevent disease. Yet people can react to treatments in completely unpredictable ways.

For example, a common and standard antibiotic treatment (think penicillin) can cause anaphylaxis, a life-threatening allergic reaction. Fortunately this is rare, but unless you or your doctor know to avoid it due to past side effects, there’s always a small chance of a severe reaction.

Often less dramatic — yet also unpreventable — harms are:

• Medication side effects. Every medicine comes with potential side effects, such as nausea, sleepiness, or rash.
• Misdiagnosis. Because no one has perfect diagnostic skills, even the most skillful health care provider can be wrong. This can result in unnecessary or delayed treatment.
• Inaccurate test results. Just as no health care provider is perfect, no test is either. False-positive results (indicating an abnormality when none is present) and false-negative results (normal results when disease is present) are common in medical practice. These results can lead to unnecessary treatment or false reassurance.

Which harms can be prevented?

Preventable harms can be dramatically reduced. They’re often due to mistakes that can be caught and corrected. Frequently, it takes a combination of things to go wrong for harm to occur.

The “Swiss cheese model” is often applied here: imagine you’re a fly trying to travel through several chunks of Swiss cheese. (I know it’s an odd scenario, but stick with me here.) It’s impossible to fly through the cheese unless the holes line up just so.

Frequently in health care, several factors must line up for an error to sneak through — for example, giving a hospitalized patient a medication to which they are allergic. For that to happen, the wrong drug has to get past the prescribing doctor, the computerized ordering system, the hospital pharmacist, the nurse giving the medication, and the patient. That’s a lot of layers, so most often an error like this will be caught.

What can you do to avoid preventable harms?

Where do you fit in? In these three scenarios, here’s what you can do to avoid preventable harms.

The problem: Taking medicines you no longer need or more medicines than necessary.

It might not seem like a big deal to keep taking a medicine if it isn’t causing any problems. But all medicines can cause side effects that you’d do better to avoid if you can safely stop taking it or reduce the dose. Plus, harmful interactions can occur if another medicine is added to your list.

What you can do: Make sure you know why you need to take each of your medicines. Ask the providers who prescribe each medicine if it is still necessary to take it or if the dose can be safely reduced. Reducing a dose may reduce the risk of side effects and the likelihood of a harmful interaction.

The problem: Taking the wrong medicine or the wrong dose.

What you can do: At your doctors’ visits, take notes or bring a friend or family member to help you remember medicine instructions. Ask whether you can record the medication instructions your doctor gives you. Take a photo of the instructions you’re given in case you lose the written version. Double-check details of your medicine list with your pharmacist. And ask questions if you’re unsure about the medicines recommended to you.

The problem: Wrong site surgery.

Despite efforts to make this a “never error,” surgery on the wrong part of the body still happens.

What you can do: Make sure you and your surgeon agree on what part of your body and which side requires surgery. Most surgeons now mark the site with a special pen before surgery and ask you to confirm the site by adding your initials. (The ink doesn’t come off easily with skin cleaners applied prior to surgery).

Some of these tips require time or resources that aren’t available to everyone: you might not be able to bring another person with you to medical visits or have a recording device. But asking questions — and getting answers you understand — should be routine.

Where does malpractice fit in?

When the topic of health care–related harm comes up, malpractice may be the first thing you think about. Yet, the approximately 10,000 malpractice payments made each year in the US likely represent only a small portion of all harm related to health care.

There are several reasons for this, including:

• Even when negligent or substandard care occurs, it doesn’t always cause major or long-lasting harm that leads to a malpractice claim.
• Many people who could file malpractice suits elect not to, or may not even realize that they’ve experienced negligent care. Past studies suggest that less than 5% of people experiencing harm related to medical care file malpractice claims.
• Increasingly, health care providers and health care systems accept responsibility for preventable harm occurring on their watch, and offer compensation rather than waiting for a legal claim to be filed.

The bottom line

It’s an unfortunate reality that some harms due to health care are inevitable. But there are steps you can take to avoid preventable harm and lessen the chances that the person harmed is you.

About the Author

Robert H. Shmerling, MD, Senior Faculty Editor, Harvard Health Publishing; Editorial Advisory Board Member, Harvard Health Publishing

Dr. Robert H. Shmerling is the former clinical chief of the division of rheumatology at Beth Israel Deaconess Medical Center (BIDMC), and is a current member of the corresponding faculty in medicine at Harvard Medical School. … See Full Bio View all posts by Robert H. Shmerling, MD

Americans love their ultra-processed foods, whether they come as cereal (like Cap’n Crunch, a favorite of mine as a kid), snack foods (like Cheetos), entr’es (like hot dogs), or desserts (like Twinkies). Sure, loading your plate with vegetables, fruits, fish, healthful oils, and grains in a Mediterranean-style diet boosts heart and brain health. But if you also eat some ultra-processed foods, is that bad for your brain health?

What to know about this new study

A new study appears to deliver resounding yes: eating ultra-processed foods is linked to a greater risk of cognitive impairment and strokes.

This well-designed observational study examined data from the REGARDS (REasons for Geographic And Racial Differences in Stroke) project, a longitudinal study of non-Hispanic Black and white Americans ages 45 years and older. Study participants were initially enrolled between 2003 and 2007 and were given a number of questionnaires evaluating health, diet, exercise, body mass index, education, income, alcohol use, mood, and other factors. In addition, tests of memory and language were administered at regular intervals.

To examine the risk of stroke and cognitive impairment, data from 20,243 and 14,175 participants, respectively, were found usable based on the quality of the information from the questionnaires and tests. Approximately one-third of the sample identified as Black and the majority of the remaining two-thirds identified as white.

The results of the study

• According to the authors’ analysis, increasing the intake of ultra-processed foods by just 10% was associated with a significantly greater risk of cognitive impairment and stroke.
• Intake of unprocessed or minimally processed foods was associated with a lower risk of cognitive impairment.
• The effect of ultra-processed foods on stroke risk was greater for individuals who identified as Black compared to individuals who identified as white.

Study participants who reported following a healthy diet (like a Mediterranean, DASH, or MIND diet) and consumed minimal ultra-processed foods appeared to maintain better brain health compared to those who followed similar healthy diets but had more ultra-processed foods.

Why might ultra-processed foods be bad for your brain?

Here are some biologically plausible reasons:

• UPFs are generally composed of processed carbohydrates that are very quickly broken down into simple sugars, equivalent to eating lots of candy. These sugar loads cause spikes of insulin, which can alter normal brain cell function.
• Eating ultra-processed foods is associated with a higher risk of metabolic syndrome and obesity, well-established conditions linked to high blood pressure, abnormal blood lipid levels, and type 2 diabetes.
• There are unhealthy additives in ultra-processed foods to change the texture, color, sweetness, or flavor. These additives disrupt the microbiome in the gut and can lead to gut inflammation that can cause
  • the production of microbiome-produced metabolites that can affect brain function (such as short-chain fatty acids and lipopolysaccharides)
  • leaky gut, allowing toxins and inflammatory molecules to enter the bloodstream and go to the brain
  • altered neurotransmitter function (such as serotonin) that can impact mood and cognition directly
  • increased cortisol levels that mimic being under chronic stress, which can directly impact hippocampal and frontal lobe function, affecting memory and executive function performance, respectively
  • an increased risk for Alzheimer’s, Parkinson’s, and other neurodegenerative diseases due to inflammatory molecules traveling from the gut to the brain.
• Because ultra-processed foods have poor nutritional value, people will often be hungry shortly after eating them, leading to overeating and its consequences.

The take-home message

Avoid processed foods, which can include chips and other snack foods, industrial breads and pastries, packaged sweets and candy, sugar-sweetened and diet sodas, instant noodles and soups, ready-to-eat meals and frozen dinners, and processed meats such as hot dogs and bologna. Eat unprocessed or minimally processed foods, which — when combined with a healthy Mediterranean menu of foods — include fish, olive oil, avocados, whole fruits and vegetables, nuts and beans, and whole grains.

About the Author

Andrew E. Budson, MD, Contributor; Editorial Advisory Board Member, Harvard Health Publishing

Dr. Andrew E. Budson is chief of cognitive & behavioral neurology at the Veterans Affairs Boston Healthcare System, lecturer in neurology at Harvard Medical School, and chair of the Science of Learning Innovation Group at the … See Full Bio View all posts by Andrew E. Budson, MD

On the Gulf Coast of Florida where I live, the telltale sign of summer is not an influx of beachcombers, afternoon storms that arrive exactly at 2 p.m., or the first hurricane warning, but the appearance of hundreds of paddleboarders dotting the inlet waters.

From afar, paddleboarding looks almost spiritual — people standing on nearly invisible boards and gliding across the surface as if walking on water.

But this popular water sport offers a serious workout, just as kayaking and canoeing do. While floating along and casually dipping a paddle in the water may look effortless, much goes on beneath the surface, so to speak.

As warm weather beckons and paddle season arrives, it pays to get key muscles in shape before heading out on the water.

Tuning up muscles: Focus on core, back, arms, and shoulders

“Paddling a kayak, canoe, or paddleboard relies on muscles that we likely haven’t used much during winter,” says Kathleen Salas, a physical therapist with Spaulding Adaptive Sports Centers at Harvard-affiliated Spaulding Rehabilitation Network. “Even if you regularly weight train, the continuous and repetitive motions involved in paddling require endurance and control of specific muscles that need to be properly stretched and strengthened.”

While paddling can be a whole-body effort (even your legs contribute), three areas do the most work and thus need the most conditioning: the core, back, and arms and shoulders.

• Core. Your core comprises several muscles, but the main ones for paddling include the rectus abdominis (that famed “six-pack”) and the obliques, located on the side and front of your abdomen. The core acts as the epicenter around which every movement revolves — from twisting to bending to stabilizing your trunk to generate power.
• Back: Paddling engages most of the back muscles, but the ones that carry the most load are the latissimus dorsi muscles, also known as the lats, and the erector spinae. The lats are the large V-shaped muscles that connect your arms to your vertebral column. They help protect and stabilize your spine while providing shoulder and back strength. The erector spinae, a group of muscles that runs the length of the spine on the left and right, helps with rotation.
• Arms and shoulders: Every paddle stroke engages the muscles in your arms (biceps) and the top of your shoulder (deltoids).

Many exercises specifically target these muscles, but here are three that can work multiple paddling muscles in one move. Add them to your workouts to help you get ready for paddling season. If you haven’t done these exercises before, try the first two without weights until you can do the movement smoothly and with good form.

Three great exercises to prep for paddling

Wood chop

Muscles worked: Deltoids, obliques, rectus abdominis, erector spinae
Reps: 8–12 on each side
Sets: 1–3
Rest: 30–90 seconds between sets

Starting position: Stand with your feet about shoulder-width apart and hold a dumbbell with both hands. Hinge forward at your hips and bend your knees to sit back into a slight squat. Rotate your torso to the right and extend your arms to hold the dumbbell on the outside of your right knee.

Movement: Straighten your legs to stand up as you rotate your torso to the left and raise the weight diagonally across your body and up to the left, above your shoulder, while keeping your arms extended. In a chopping motion, slowly bring the dumbbell down and across your body toward the outside of your right knee. This is one rep. Finish all reps, then repeat on the other side. This completes one set.

Tips and techniques:

• Keep your spine neutral and your shoulders down and back
• Reach only as far as is comfortable.
• Keep your knees no farther forward than your toes when you squat.

Make it easier: Do the exercise without a dumbbell.

Make it harder: Use a heavier dumbbell.

Bent-over row

Muscles worked: Latissimus dorsi, deltoids, biceps
Reps: 8–12
Sets: 1–3
Rest: 30–90 seconds between sets

Starting position: Stand with a weight in your left hand and a bench or sturdy chair on your right side. Place your right hand and knee on the bench or chair seat. Let your left arm hang directly under your left shoulder, fully extended toward the floor. Your spine should be neutral, and your shoulders and hips squared.

Movement: Squeeze your shoulder blades together, then bend your elbow to slowly lift the weight toward your ribs. Return to the starting position. Finish all reps, then repeat with the opposite arm. This completes one set.

Tips and techniques:

• Keep your shoulders squared throughout.
• Keep your elbow close to your side as you lift the weight.
• Keep your head in line with your spine.

Make it easier: Use a lighter weight.

Make it harder: Use a heavier weight.

Superman

Muscles worked: Deltoids, latissimus dorsi, erector spinae
Reps: 8–12
Sets: 1–3
Rest: 30–90 seconds between sets

Starting position: Lie face down on the floor with your arms extended, palms down, and legs extended.

Movement: Simultaneously lift your arms, head, chest, and legs off the floor as high as is comfortable. Hold. Return to the starting position.

Tips and techniques:

• Tighten your buttocks before lifting.
• Don’t look up.
• Keep your shoulders down, away from your ears.

Make it easier: Lift your right arm and left leg while keeping the opposite arm and leg on the floor. Switch sides with each rep.

Make it harder: Hold in the “up” position for three to five seconds before lowering.

About the Author

Matthew Solan, Executive Editor, Harvard Men's Health Watch

Matthew Solan is the executive editor of Harvard Men’s Health Watch. He previously served as executive editor for UCLA Health’s Healthy Years and as a contributor to Duke Medicine’s Health News and Weill Cornell Medical College’s … See Full Bio View all posts by Matthew Solan

About the Reviewer

Howard E. LeWine, MD, Chief Medical Editor, Harvard Health Publishing

Dr. Howard LeWine is a practicing internist at Brigham and Women’s Hospital in Boston, Chief Medical Editor at Harvard Health Publishing, and editor in chief of Harvard Men’s Health Watch. See Full Bio View all posts by Howard E. LeWine, MD