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While the FDA rules for blood donation were revised twice in the last decade, one group — men who have sex with men (MSM) — continued to be turned away from donating. Now new, evidence-based FDA rules embraced by the American Red Cross will focus on individual risk rather than groupwide restrictions.

Medical experts consider the new rules safe based on extensive evidence. Let’s review the changes here.

The new blood donation rules: One set of questions

The May 2023 FDA guidelines recommend asking every potential blood donor the same screening questions. These questions ask about behavior that raises risk for HIV, which can be spread through a transfusion.

Blood donation is then allowed, or not, based on personal risk factors for HIV and other blood-borne diseases.

Questions for potential blood donors

Screening questions focus on the risk of recent HIV infection, which is more likely to be missed by routine testing than a longstanding infection.

The screening questions ask everyone — regardless of gender, sex, or sexual orientation — whether in the past three months they have

• had a new sexual partner and engaged in anal sex
• had more than one sexual partner and engaged in anal sex
• taken medicines to prevent HIV infection (such as pre-exposure prophylaxis, or PrEP)
• exchanged sex for pay or drugs, or used nonprescription injection drugs
• had sex with someone who has previously tested positive for HIV infection
• had sex with someone who exchanged sex for pay or drugs
• had sex with someone who used nonprescription injection drugs.

When is a waiting period recommended before giving blood?

• Answering no to all of these screening questions suggests a person has a low risk of having a recently acquired HIV infection. No waiting period is necessary.
• Answering yes to any of these screening questions raises concern that a potential donor might have an HIV infection. A three-month delay before giving blood is advised.

Does a waiting period before giving blood apply in other situations?

Yes:

• A three-month delay before giving blood is recommended after a blood transfusion; treatment for gonorrhea or syphilis; or after most body piercings or tattoos not done with single-use equipment. These are not new rules.
• A waiting period before giving blood is recommended for people who take medicines to prevent HIV infection, called PrEP (pre-exposure prophylaxis). PrEP might cause a test for HIV to be negative even if infection is present. The new guidelines recommend delaying blood donation until three months after the last use of PrEP pills, or a two-year delay after a person receives long-acting, injected PrEP.

Who cannot donate blood?

Anyone who has had a confirmed positive test for HIV infection or has taken medicines to treat HIV infection is permanently banned from donating blood. This rule is not new.

Why were previous rules more restrictive?

In 1983, soon after the HIV epidemic began in the US, researchers recognized that blood transfusions could spread the infection from blood donor to recipient. US guidelines banned men who had sex with men from giving blood. A lifetime prohibition was intended to limit the spread of HIV.

At that time, HIV and AIDS were more common in certain groups, not only among MSM, but also among people from Haiti and sub-Saharan Africa, and people with hemophilia. This led to blood donation bans for some of these people, as well.

A lot has changed in the world of HIV in the last several decades, especially the development of highly accurate testing and highly effective prevention and treatment. Still, the rules regarding blood donation were slow to change.

The ban from the 1980s for MSM remained in place until 2015. At that time, rules were changed to allow MSM to donate only if they attested to having had no sex with a man for 12 months. In 2020, the period of sexual abstinence was reduced, this time to three months.

Why are the blood donation guideline changes important?

• Removing unnecessary restrictions that apply only to certain groups is a step forward in reducing discrimination and stigma for people who wish to donate blood but were turned away in the past.
• The critical shortage in our blood supply has worsened since the start of the COVID-19 pandemic. These revised rules are expected to significantly boost the number of blood donors.

The bottom line

Science and hard evidence should drive policy regarding blood donation as much as possible. Guidelines should not unnecessarily burden any particular group. These new guidelines represent progress in that regard.

Of course, these changes will be closely monitored to make sure the blood supply remains safe. My guess is that they’ll endure. And it wouldn’t surprise me if there is additional lifting of restrictions in the future.

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

There are certain things our bodies do so often and so automatically that we barely notice them. Yawning, growling stomachs, and runny noses are good examples. Each is a universal part of our daily human experience.

But did you ever wonder why? Below are a few things we know and a few we suspect.

Why do you yawn?

Perhaps you associate yawning only with being tired or bored. While we don’t know exactly why people yawn, there’s no shortage of theories. Yawning may

• stretch out our lungs and nearby tissues, preventing tiny airways in the lungs from collapsing
• distribute a chemical called surfactant, a gooey liquid that coats the tiny air pockets in the lungs and helps keep them open
• help prepare our bodies for transitions between wakefulness and rest: For example, yawning often occurs after a period of relaxation and when awakening from sleep. And it may serve as an internal signal that it’s time to sleep, or time to take a break from activities (such as driving).
• play a role in maintaining proper brain temperature: Our brain functions best within a narrow range of temperatures. Some experts believe yawning can help cool the brain through complex effects on nearby circulation and the sinuses.

It’s also unclear why yawning is contagious. In the animal kingdom, it’s common to see contagious yawning among members of a group, perhaps as a signal for collective behavior (such as moving from activity to rest).

Why does your stomach growl?

That rumbling in your stomach is known medically as borborygmi — an excellent Scrabble word if you have the right letters. We usually assume it reflects hunger. And it’s true that the experience of hunger can make itself heard in anticipation of a meal.

But your stomach may also growl after a meal, when the stomach and intestines propel liquids and food through the digestive tract. Stress can also trigger stomach rumbling.

What’s causing all that noise — and is it ever a problem? It may be due to gas moving around in response to muscular contractions of the intestinal walls. Occasionally, noises from the abdomen may be a sign of an intestinal infection or other trouble. If you’re experiencing other symptoms, such as pain or fever, check in with your doctor. But the vast majority of noises are harmless and a sign that your gut is working normally.

Why does your nose run?

Sometimes it can seem like your nose is running for no reason. But there are some well-known triggers, such as:

• Infection. When you have a cold, mucous membranes produce more mucus as part of your defense system: more mucous flowing out means fewer germs getting in.
• Allergies. Pollen, ragweed, or other triggers stimulate immune cells that produce histamine. Histamine opens up blood vessels just beneath the mucous membranes, and that leads to increased production and release of fluid and mucus. As with infection, this response may be helpful to dilute the offending trigger and rid it from the area.
• Cold, dry air. The inside surface of the nose is covered with mucous membranes that warm and humidify air well before it reaches the lungs. When you inhale dry, cold air through your nose, these membranes humidify the air by secreting water and mucus.
• Spicy foods. Spices like capsaicin act as an irritant to the sinuses and mucous membranes, which release fluid in response.

The bottom line

Some of the most common everyday human experiences are also some of the least understood. There are many other examples, of course: Why are we ticklish? What purpose do hiccups serve? What’s the deal with brain freeze? Perhaps topics for another day.

It may seem like a leap of faith, but it’s likely there are very good reasons for the way our bodies work — even when we don’t know what those reasons are.

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

We can feel groggy when our sleep schedule is thrown off even just a little. So what happens when shift work requires people to regularly stay awake through the night and sleep during the day — and how can they protect their health and well-being?

What is shift work disorder?

Mounting evidence, including several new studies, paints a worrisome picture of the potential health fallout of nontraditional shift work schedules that affect 15% to 30% of workers in the US and Europe, including factory and warehouse workers, police officers, nurses, and other first responders.

So-called shift work disorder mainly strikes people who work the overnight or early morning shift, or who rotate their shifts, says Eric Zhou, an assistant professor in the Division of Sleep Medicine at Harvard Medical School. It is characterized by significant problems falling and staying asleep, or sleeping when desired. That’s because shift work disrupts the body’s normal alignment with the 24-hour sleep-wake cycle called the circadian rhythm.

“People who work 9-to-5 shifts are typically awake when the sun is up, which is aligned with their body’s internal circadian clock. But for shift workers, their work hours and sleep hours are misaligned with the natural cues to be awake or asleep,” Zhou says. “They’re working against the universe’s natural inclinations — not just their body’s.”

What’s the connection between shift work and health?

A 2022 research review in the Journal of Clinical Sleep Medicine links shift work to higher risks for serious health problems, such as heart attack and diabetes. This research suggests adverse effects can include metabolic syndrome (a cluster of conditions that raises the risks for heart disease, diabetes, and stroke), accidents, and certain types of cancer.

“The research is consistent and powerful,” Zhou says. “Working and sleeping during hours misaligned with natural light for extended periods of time is not likely to be healthy for you.”

How do new studies on shift work boost our understanding?

New research continues to add to and strengthen earlier findings, teasing out specific health effects that could stem from shift work.

• Shift workers on rotating schedules eat more erratically and frequently than day workers, snack more at night, and consume fewer healthier foods with potentially more calories, a study published online in Advances in Nutrition suggests. This analysis reviewed 31 prior studies involving more than 18,000 participants, comparing workers’ average food intake over 24 hours.
• Disrupting the circadian rhythm through shift work appears to increase the odds of colorectal cancer, a malignancy with strong ties to lifestyle factors, according to a 2023 review of multiple studies published online in the Journal of Investigative Medicine. Contributors to this higher risk may include exposure to artificial light at night, along with complex genetic and hormonal interactions, study authors said.

“Cancer understandably scares people, and the World Health Organization recognizes that shift work is a probable carcinogen,” Zhou says. “The combination of chronically insufficient and poor-quality sleep is likely to get under the skin. That said, we don’t fully understand how this happens.”

How can you protect your sleep — and your health?

If you work overnight or early morning shifts, how can you ensure you sleep more soundly and restfully? Zhou offers these evidence-based tips.

Time your exposure to bright and dim light. Graveyard shift workers whose work schedule runs from midnight through 8 a.m., for example, should reduce their light exposure as much as possible after leaving work if they intend to go right to sleep once they return home. “These measures could take the form of wearing blue light–blocking glasses or using blackout shades in your bedroom,” he says.

Make enough time for sleep on days off. “This is often harder than it sounds, because you’ll want to see your family and friends during nonwork hours,” Zhou says. “You need to truly protect your opportunity for sleep.”

Maintain a consistent shift work schedule. “Also, try to minimize the consecutive number of days you spend working challenging shifts,” he says.

Talk to your employer. Perhaps your boss can schedule you for fewer overnight shifts. “You can also ask your doctor to make a case for you to be moved off these shifts or have more flexibility,” Zhou says.

Look for practical solutions that allow you to get more restful sleep. “People engaged in shift work usually have responsibilities to their job as well as their family members, who often operate under a more typical 9-to-5 schedule,” he notes. “The goal is to preserve as strong a circadian rhythm as possible under the abnormal schedule shift work requires.”

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

We’re bombarded with advertisements that tout all sorts of health benefits for vitamins and supplements, including improved memory. A May 2023 study of older adults suggests that a daily multivitamin can do just that — improve your memory enough such that it can function as if you were three years younger.

So, should you take that daily multivitamin? Let’s take a close look at the study.

Who took part in this multivitamin study?

This research is part of a larger study examining the effects of a multivitamin and/or cocoa (the main ingredient in chocolate) on cardiovascular and cancer outcomes. A prior sub-study found that a daily multivitamin improved thinking and memory — at least when evaluated with cognitive testing completed by phone.

For this study, 3,562 participants were willing and able to perform some tests of thinking and memory on a home computer. Half received a multivitamin; the other half received a placebo.

The participants identified as 93% white, 2.5% African American, and 1.4% Hispanic, so the results may not be generalizable. They were also well educated: more than half had completed college. In both groups, the average age was 71.

How did the researchers test memory?

The investigators evaluated the participants’ thinking and memory at baseline and after one, two, and three years.

For the memory test, participants were asked to memorize 20 words shown consecutively on a computer screen. Immediately after viewing these words, they had to type in as many words as they could remember (this was the primary measure of memory). Fifteen minutes later, they also typed in all the words they recalled (a secondary measure of memory).

Other secondary measures included:

• a novel object discrimination test (is this object the same or different from one recently shown?)
• an executive control test (in an array of nine arrows, is the central arrow red or blue?).

The participants repeated all of the tests one, two, and three years later.

What were the results of this study?

The two groups differed in immediate recall at year one:

• Those who took a placebo went from immediately recalling an average of 7.21 words at baseline to 7.65 words (a difference of 0.43 words)
• Those who took a daily multivitamin group went from 7.10 words at baseline to 7.81 words (a difference of 0.70 words).

This result was statistically significant. Additionally, these small effects held up at years two and three. By year three, the placebo group immediately recalled an average of 8.17 words and the multivitamin group immediately recalled 8.28 words.

No differences occurred between the two groups on secondary memory and executive function tests.

How can a multivitamin improve memory?

The authors note that low levels of vitamins B12 and D have been linked to cognitive decline and dementia. In a subset of participants who had their blood drawn, the levels of these vitamins did rise in the multivitamin group.

It seems plausible that a few of the 3,562 participants had low levels of these or other vitamins that are important for thinking and memory. In the placebo group, the few who had vitamin deficiencies would likely show less improvement in memory after their baseline tests, or a small decline. By contrast, those few participants in the multivitamin group with deficiencies would have them corrected by the supplements and, therefore, would perform relatively better.

Although this is just speculation, it would explain the small but seemingly real results — results that replicate the researchers' prior study, which used a telephone cognitive test to show thinking and memory benefit from a daily multivitamin.

It’s also worth noting that practice on memory tasks — the so-called practice effect — could contribute to small improvements shown from baseline to year one and year three.

Should you take a multivitamin to improve your memory?

The authors admitted that the effect of the multivitamin on immediate memory was small and may not be noticeable. However, they pointed out that this small effect could be important at the level of an entire population.

My opinion? You shouldn’t bother taking a multivitamin to try to improve your immediate recall of 20 words from 8.17 to 8.28 words. But it is worth speaking with your doctor about whether you could have a vitamin deficiency in B1, B6, B12, D, or any other important vitamins. I see several patients in my clinic every week who have startlingly low levels of vitamin D and B12. Your doctor may want to measure these levels. Or they may suggest simply taking a multivitamin daily.

If, after reading this article, you’ve decided to take a multivitamin, please check with your doctor or pharmacist about which one would be best for you. Make sure that they review any other vitamins, supplements, and medications you take to avoid rare but serious interactions.

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

I admit it: I’m not a fan of drug ads. I think the information provided is often confusing and rarely well-balanced. Plus, there are just so many ads. They show up on TV and streaming programs, on social media, on billboards and the sides of busses, on tote bags, and in public bathrooms. Yes, there’s no refuge — even there — from the billions spent on direct-to-consumer ads in the US.

I’ve often wondered how highly-promoted, expensive new drugs stack up against other available treatments. Now a new study in JAMA Network Open considers exactly that.

Many advertised drugs are no better than older drugs

The study assessed 73 of the most heavily advertised drugs in the US between 2015 and 2021. Each drug had been rated by at least one independent health agency. Researchers tallied how many of these drugs received a high therapeutic value rating, indicating that a drug had at least a moderate advantage compared with previously available treatments.

The results? Only about one in four of these heavily advertised drugs had high therapeutic value. During the six years of the study, pharmaceutical companies spent an estimated $15.9 billion promoting drugs on TV that showed no major advantage over less costly drugs!

Why drug ads are not popular

Only the US and New Zealand allow direct-to-consumer medication marketing. The American Medical Association recommended a ban in 2015. While I’ve often written about reasons to be skeptical, let’s focus here on three potential harms to your wallet and your health.

Drug ads may

• raise already astronomical health care costs by increasing requests for unnecessary treatment and promoting much costlier medicines than older or generic drugs.
• create diseases to be treated. Everyday experiences, such as fatigue or occasional dryness in the eyes, may be framed in drug ads as medical conditions warranting immediate treatment. Yet often, such symptoms are minor, temporary experiences. Another example is “low T” (referring to low blood testosterone). While it’s not a recognized illness on its own, ads for it have likely contributed to increased prescriptions for testosterone-containing medicines.
• promote new drugs before enough is known about long-term safety. The pain reliever rofecoxib (Vioxx) is one example. This anti-inflammatory medicine was supposed to be safer than older medicines. It was withdrawn from the market when evidence emerged that it might increase the risk of heart attack and stroke.

Four questions to ask your doctor if you’re curious about a drug ad

Wondering whether you should be taking an advertised drug? Ask your doctor:

• Do I have a condition for which this drug is recommended?
• Is there any reason to expect this drug will be more helpful than what I’m already taking?
• Is this drug more expensive than my current treatment?
• Do my health conditions or the medications I already take make the drug in the ad a poor choice for me?

The bottom line

The AMA recommended banning drug ads nearly a decade ago. But a drug ad ban seems unlikely, given strong lobbying by the pharmaceutical companies and concerns about violating their freedom of speech.

Still, cigarette commercials were banned in 1971, so it’s not an impossible dream. Meanwhile, my advice is to be skeptical about information in drug ads, and rely on more reliable sources of medical information, including your doctor. Consider contacting the Federal Communications Commission if you have complaints about these ads — a step few Americans seem to take. And try this: mute the TV, fast-forward your podcast, and close pop-ups as soon as drug ads appear.

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

At some point in life, everyone experiences denial, a natural response when you’re unable or unwilling to face the facts. Denial is not always a bad thing. But it might be easier to recognize in others than in yourself.

“It’s hard to look at your own life and take a good inventory of what’s going on. It takes a lot of work,” says Jonathan Scholl, a therapist and clinical social worker at Harvard-affiliated McLean Hospital.

Here’s a little insight about denial, how to spot it in yourself and others, and what you might want to do about it.

What is denial?

In psychological terms, denial is a defense mechanism, a skillful tool the mind can employ when things get tough. “I see it as a protective barrier we have that we might or might not be aware of,” Scholl says. “It keeps us safe. It also keeps us from looking at ourselves or addressing something around us and making a change.”

You can be in denial about something you’re not ready to admit or take on, or something that challenges deeply held beliefs.

Common triggers for denial can involve

• abuse (mental, emotional, physical, verbal, sexual, financial, or other types of abuse)
• alcohol in excess or other substance use, or substance use disorder
• lifestyle or family issues
• medical diagnoses
• mental health issues
• politics
• smoking
• unhealthy weight gain.

How does denial help us?

Denial can shield us from difficult emotions. Scholl says that might be helpful in the short term, and provide relief to people who don’t have the bandwidth or ability to face a problem.

For example, maybe someone is unhappy in a relationship, but the thought of being alone is worse than the thought of being together. Or perhaps someone is burned out or overwhelmed, and lacks the energy or emotional capability for accepting what’s happening. “Part of the person feels it’s easier not to think about the situation, and lets it go because it feels like it’s too much to handle right now,” Scholl says.

How can denial hurt us?

In dangerous or unhealthy situations, denial can hurt us.

For example, keeping our eyes shut about the realities of a physical or mental illness can lead to serious health consequences. “We see a lot of teens with depression and substance use disorders, and some parents deny there are problems because they’re afraid of what it means for the child. It comes from a place of worry,” Scholl says. “But denying problems can hurt children and block them from making meaningful change.”

Denial can also hurt when it involves addiction or abuse. Those problems affect everyone in a family, and can lead to unhealthy patterns that get passed down from one generation to the next.

Spotting behavior patterns that suggest denial

People in denial often exhibit certain behaviors. For example, they might

• minimize or justify problems, issues, or unhealthy behaviors
• avoid thinking about problems
• avoid taking responsibility for unhealthy behaviors, or blame them on someone else
• refuse to talk about certain issues, and get defensive when the subjects are brought up.  

Moving from denial toward meaningful change

Dealing with denial means first recognizing that it’s occurring — which can be a challenge for anyone — and then addressing the underlying issue that’s causing it.

If you recognize denial in yourself, Scholl advises that you reach out for help. Talk to someone close to you or get an outside opinion from a therapist, a spiritual counselor, your doctor, or a hotline number, such as the National Domestic Violence Hotline if you’re experiencing intimate partner violence. For addiction problems, make that first call to a substance use disorder hotline or recovery center, or try attending just one meeting of a 12-step program (such as Alcoholics Anonymous). In time, you can learn to face your fears or concerns, and develop a concrete plan to change.

Recognizing denial in others: Tread carefully

If you recognize denial in others and you’d like to point it out, tread very carefully. Seek guidance from experts before taking on a situation that could be dangerous to you or to the other person.

If the situation is not dangerous, be as compassionate as possible. “Have a warm and empathetic conversation in an environment without distractions,” Scholl says. “Express your love and point out what you’re seeing. Talk about how it affects you. And then give it time. You can’t force anyone to change. All you can do is plant a seed.”

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

The first two weeks of July were the Earth’s hottest on human record, and people across the country continue to suffer from lingering, suffocating heat waves. The US Centers for Disease Control and Prevention has issued repeated warnings and tips about recognizing and preventing heat-related illnesses, like heat stroke, heat exhaustion, and heat cramps.

But one heat-related illness that people do not always recognize is heat rash.

“Heat rash can indicate that your exposure to excessive heat could lead to other serious heat-related issues, if not addressed,” says Dr. Abigail Waldman, a dermatologist with Harvard-affiliated Brigham and Women’s Hospital. "While heat rash is not dangerous in itself, sustained exposure to high heat can lead to heat exhaustion and heat stroke, so it's important to note any early signs that your body is struggling with the heat.”

What are the signs of heat rash?

Heat rash is also known as miliaria or prickly heat. It is caused when ducts from eccrine sweat glands that lead to the skin's surface are blocked or inflamed.

Eccrine sweat glands help your body maintain a steady temperature. When your internal temperature rises, these glands release water that rises to the surface of your skin through tiny ducts. There, it quickly evaporates, cooling your skin and the blood beneath.

However, sweat ducts may get blocked when you sweat excessively in hot temperatures, particularly if skin folds or tight-fitting clothes hinder their function.

Sweat is then trapped beneath the skin. This triggers inflammation, which leads to the appearance of small, itchy red bumps, similar to tiny pimples or blisters. In people with darker skin tones, these small, itchy bumps may not appear red, but will look slightly darker than surrounding skin.

Where and when is heat rash likely to occur?

Heat rash can appear on the neck, scalp, chest, groin, or elbow creases.

“Heat rash can occur any time the body sweats, so it is common in hot, humid climates, during hospitalizations, from fever, and during exercise,” says Dr. Waldman.

Heat rash also can occur in newborns, as their eccrine sweat glands are not fully developed. In newborns, heat rash looks like very thin blisters or water drops widely distributed on the face, trunk, arms, and legs. Call your pediatrician for advice if you notice a rash like this.

How can you treat heat rash?

Heat rash in adults is easy to treat with home remedies. “The techniques to relieve symptoms also can help prevent heat rash for adults and babies,” says Dr. Waldman.

• Cool down. The first step is to get out of the heat and cool and dry your skin. Use a fan or air conditioner, take a cool shower, or apply cool compresses to the affected areas. It's important to know that some people are more vulnerable to heat, and to make plans to help stay safe when temperatures are dangerously high.
• Prevent irritation. To prevent skin irritation, avoid wearing clothes made from synthetic materials, which can trap heat. (While dry-fit clothing helps to wicks away moisture from the skin, it often can be too tight fitting.) Instead, wear light, loose-fitting cotton clothing that allows airflow over your skin. If a heat rash occurs around your groin area, avoid wearing undergarments until it clears up.
• Try anti-itch products. Use an over-the-counter topical corticosteroid cream or calamine lotion for itching. However, avoid baby powder, oily or greasy moisturizers, and sunscreen, as they can further block sweat ducts.

Heat rash typically goes away within one to two days once you cool down your body. More severe heat rashes can last a week or longer. See your doctor (or follow up with your pediatrician) if a heat rash has not cleared up after a week. Also seek immediate care if you experience pain, intense itching, or the rash appears infected.

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

Heavy rains and sea level rise contribute to major flooding events that are one effect of climate change. Surging water rushing into buildings often causes immediate harms, such as drowning deaths, injuries sustained while seeking shelter or fleeing, and hypothermia after exposure to cold waters with no shelter or heat.

But long after news trucks leave and public attention moves on, flooding continues to affect communities in visible and less visible ways. Among the less visible threats is a higher risk of respiratory health problems like asthma and allergic reactions. Fortunately, you can take steps to minimize or avoid flooding, or to reduce respiratory health risks after flooding occurs.

How does flooding trigger respiratory health issues?

Flooding may bring water contaminated with toxic chemicals, heavy metals, pesticides, biotoxins, sewage, and water-borne pathogens into buildings. Afterward, some toxic contaminants remain in dried sediments left behind. When disturbed through everyday actions like walking and cleaning, this turns into microscopic airborne dust. Anything in that dried flood sediment — the toxic chemicals, the metals, the biotoxins — is now in the air you breathe into your lungs, potentially affecting your respiratory health.

Buildings needn’t be submerged during flooding to spur respiratory problems. Many homes we studied after Hurricane Ida suffered water intrusion through roofs, windows, and ventilation ducts — and some were more than 100 miles away from coastal regions that bore the brunt of the storm.

The growth of mold can also affect health

Another common hazard is mold, a fungal growth that forms and spreads on damp or decaying organic matter. Indoor mold generally grows due to extensive dampness, and signals a problem with water or moisture. Damp materials inside buildings following a flood create perfect conditions for rapid mold growth.

Mold can be found indoors and outdoors in all climates. It spreads by making tiny spores that float through the air to land in other locations. No indoor space is entirely free from mold spores, but exposure to high concentrations is linked with respiratory complications such as asthma, allergic rhinitis, and sinusitis. Thus, flooding affects respiratory health by increasing the risk of exposure to higher concentrations of mold spores outdoors and indoors.

For example, after Hurricane Katrina in New Orleans in 2005, the average outdoor concentration of mold spores in flooded areas was roughly double that of non-flooded areas, and the highest concentrations of mold spores were measured indoors. A study on the aftermath of Hurricane Katrina and the flooding in the UK in 2007 showed that water damage accelerated mold growth and respiratory allergies.

Children are especially vulnerable to health problems triggered by mold. All respiratory symptoms — including asthma, bronchitis, eye irritation, and cough — occurred more often in homes reporting mold or dampness, according to a study on the respiratory health of young children in 30 Canadian communities. Other research demonstrates that mold contributes to development of asthma in children.

What can you do to protect against the health harms of flooding?

Our research in New Orleans, LA after Hurricane Ida in 2021 identified common factors — both in housing and flooding events — with great impact on respiratory health. Preliminary results suggest two deciding factors in whether substantial indoor mold appeared were the age of a building’s roof and how many precautionary measures people took after flooding from the hurricane. The impact on respiratory health also varied with flood water height, days per week spent at home, and how many precautionary measures were taken after Ida swept through.

Informed by this and other research, we offer the following tips — some to tackle before flooding or heavy rains, and some to take afterward. While you may not be able to entirely prevent flooding from hurricanes or major storms, taking these and other steps can help.

Before seasonal storms, flooding, or heavy rains start: Protect against water intrusion

• Repair the roof, clean gutters, and seal around skylights, vent pipes, and chimneys to prevent leaks. These are some of the most vulnerable components of a building during storms and hurricanes.
• Declutter drains and empty septic tanks.
• Construct barriers and seal cracks in outer walls and around windows, to prevent heavy rain and floodwater from entering.
• Install a sump pump to drain water from the basement, and backflow valves on sewer lines to prevent water from backing up into the home.

After flooding or major rainstorms: Move quickly to reduce dampness and mold growth

The Environmental Protection Agency recommends limiting contact with flood water, which may have electrical hazards and hazardous substances, including raw sewage. Additionally:

• Minimize your stay in flooded regions (particularly after hurricanes) or buildings until they are dry and safe.
• Check building for traces of water intrusion, dampness, and mold growth immediately after flooding.
• Drain floodwater and dispose of remaining sediment.
• Remove affected porous materials. If possible, dry them outdoors under sunlight.
• Increase the ventilation rate by leaving all windows and doors open, or use a large exhaust fan to dry out the building as fast as possible.
• Use dehumidifiers in damp spaces such as basements.
• Upgrade the air filters in your HVAC system to at least MERV 13, or use portable air cleaners with HEPA filters to reduce your exposure to airborne mold spores.

What to do if you spot mold growth

• Wear a well-fitted N95 face mask, gloves, and rubber boots to clean.
• Clean and disinfect anything that has been in contact with water using soap, detergents, and/or antibacterial cleaning products.
• Dispose of moldy materials in sealed heavy-duty plastic bags.

Taking steps like these — before and after a major storm — goes a long way toward protecting your respiratory health.

Read Flooding Brings Deep Trouble in Harvard Medicine magazine to learn more about the health hazards related to floods.

About the Authors

Parham Azimi, PhD, Contributor

Dr. Parham Azimi is a research associate in the department of environmental health at the Harvard T.H. Chan School of Public Health, investigating the indoor environment’s impact on occupant health and wellness and strategies to improve … See Full Bio View all posts by Parham Azimi, PhD

Joseph Allen, DSc, MPH, CIH, Contributor

Dr. Joseph Allen is an associate professor in the department of environmental health at the Harvard T.H. Chan School of Public Health, and the director of Harvard’s Healthy Buildings Program. He is the coauthor of Healthy … See Full Bio View all posts by Joseph Allen, DSc, MPH, CIH

Your face plays an outsized role in your interactions with the world. It’s usually the first thing a person notices when they look at you. It’s home to the eyes, nose, and mouth, vital body parts that allow you to eat, drink, and communicate. But our facial features are also engineered for their own self-protection — and help protect our bodies in many surprising ways.

My brief career as a cowpoke

I learned how the human face is designed for self-protection while whipping around a lasso I’d been given as a birthday gift. At 8, I’d seen enough cowboy movies to think I knew how use it, at least until the rope struck me across my face. Within seconds a raised red streak ran across my forehead, eyebrow, and cheek. But it skipped my eye.

Once sure I was okay, my mom pointed out that being set back and surrounded by my eye socket bones had protected my eye from damage.

I learned two important lessons that day. First, facial anatomy is remarkably good at protecting itself. Second, using a lasso is harder than it looks.

How do your eyes help protect your body?

Our eyes help keep us safe by feeding detailed information about our surroundings to the brain. Having two eyes pointing ahead (rather than just one) allows for depth perception and a wider field of vision.

What’s more:

• Eyebrows help guide debris, sweat, rainwater, or other substances that find their way onto your forehead away from your eyes. They also communicate emotions, as is obvious if you compare the positions of a person’s eyebrows when they are angry, surprised, or fearful.
• Eyelashes act as guards at the front of the eyes, preventing dust, sweat, and other irritants from making it into the eye. And because lashes are sensitive to touch, they can also provide an alert when something is near the eye.
• The cornea protects your eyes from what may be harmful in the environment while allowing light to pass through to reach nerves at the back of the eye. The cornea is perfectly suited for these tasks: its tough outer coating shields the front of the eye, but is clear so that light can pass through it.

How does your nose help protect your body?

The nose that allows us to smell flowers, bread baking, and other pleasant scents also serves as an alarm system: if there’s a gas leak or if food has spoiled, a good sense of smell can be lifesaving. It also warms and humidifies air passing through. That’s important because cold, dry air can be irritating to the lungs.

Additionally:

• Nose hairs help filter larger particles, such as dust or soot, from the air.
• The nasal liningteams with immune cells ready to attack toxic particles from the air, viruses, or other intruders. It also produces protective mucus that can trap small particles and keep nasal passages from drying out.
• Sneezing expels small particles, such as microorganisms or chemical irritants, out through the nose.

How does your mouth help protect your body?

Eating, drinking, and speaking are among the most important functions of the mouth, but there are other ways it’s protective:

• A tight seal forms when you close your mouth. That’s helpful, because otherwise we’d have a hard time swimming — or even just walking around — and might be constantly swallowing bugs (among other challenges)
• Coughing allows you to expel unwanted particles or organisms through your mouth.
• Saliva contains antibodies to attack infectious organisms before these travel further into the body.
• The mucous membranes that line the inside of the mouth allow for the sensation of taste. That’s important for quality of life, and for avoiding eating something toxic. And the mucous membranes host key immune cells, serving as a first-line immune barrier against viruses and other infectious organisms.

The evolution of the human face

How is it that the human face developed to protect its host in so many ways?

As is so often the case with the human body, you can thank evolution. Over thousands of years, evolutionary pressure ensured that features favoring survival were preserved in our genetic makeup.

This includes facial anatomy: each element of your face is there for a reason, from its shape, form and function to its various attachments and orifices. Even features that humans consider attractive (such as symmetry, youthfulness, or familiarity) are partly due to evolutionary pressure: these features help attract mates, and therefore may increase the chances of passing on genes to offspring.

The bottom line

Remarkable features of the human face serve to protect itself and its host. Unlike communication and social interactivity, these features are less well known and probably underappreciated.

So, the next time you look at yourself in the mirror, go ahead: Check how good you look. Or for signs of aging. Or for lettuce in your teeth. But whatever you’re searching for, remember: there’s a lot more to the appearance of your face than how you look.

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

In June, the FDA approved a new treatment for the most advanced type of prostate cancer. Patients who have this condition, which is called metastatic castration-resistant prostate cancer (mCRPC), have few therapeutic options, so the approval helps to fill an urgent need.

mCRPC sets in when the front-line hormonal therapies that doctors use first for treating metastatic prostate cancer stop working. These drugs limit the body’s production of testosterone, a hormone that fuels prostate cancer growth. If they are no longer effective, then doctors switch to a different class of drugs known as anti-androgens that further inhibit testosterone by blocking its cell receptor. One of those drugs is called enzalutamide.

The newly approved treatment combines enzalutamide with a second drug, talazoparib, that was already on the market for female cancer patients who test positive for BRCA mutations. These inherited gene defects boost risks for breast and ovarian cancer, but they can also elevate risks for prostate cancer in men. Indeed, an estimated 10% of men with metastatic prostate cancer are BRCA-positive.

Talazoparib inhibits a DNA-repair system called PARP that the tumor cells need to keep their own genes in working order. When PARP is blocked by treatment, the cancer cells will eventually die. Other PARP inhibitors, including olaparib and rucaparib, are already approved for advanced prostate cancer in BRCA-positive men.

During research leading to this latest approval, 399 men with mCRPC were randomly divided into two groups. One group received talazoparib plus enzalutamide; the other group was treated with enzalutamide plus placebo. The men averaged 70 years in age, and most of them had already been treated with chemotherapy and/or a different anti-androgen called abiraterone. All the men were positive for either BRCA mutations or defects affecting other DNA-repair genes.

What the study showed

Results from the still-unpublished study were presented at the 2023 American Society of Oncology Annual Meeting in June. After a median follow-up of roughly 17 months, the enzalutamide/talazoparib combination reduced the risk of death or visible signs of tumor progression by 55%.

Among the specific subgroup of BRCA-positive patients, “there was an 80% reduction in risk progression or death, which is enormous for these men and obviously very welcome,” said lead researcher Dr. Karim Fizazi, a professor at the University of Paris-Saclay in France.

Scientists had hoped that combining PARP inhibitors with anti-androgens would similarly benefit prostate cancer patients with no DNA-repair defects, but evidence from a different study by Dr. Fizazi and his colleagues shows they do not.

For that reason, the FDA approved the new combination only for mCRPC patients who test positive for mutations affecting DNA-repair genes. Dr. Fizazi and his colleagues are continuing to monitor the enrolled patients for improvements in other areas, such as overall survival, quality of life, and subsequent need for chemotherapy.

Dr. David Einstein, an assistant professor of medicine at Harvard Medical School and a medical oncologist at Beth Israel Deaconess Medical Center in Boston, says the evidence helps to confirm that PARP inhibitors have a role to play in genetically-selected men with mCRPC. Additional research is needed to assess if the observed benefits are “specific to the combination or just because access to PARP inhibition was provided at some point in the disease course,” he says.

“Genetic testing for BRCA, which originally targeted females, is now becoming mainstream for men with a family history of breast and ovarian cancers, as well as men with mCRPC regardless of family history,” says Dr. Marc B. Garnick, the Gorman Brothers Professor of Medicine at Harvard Medical School and Beth Israel Deaconess Medical Center. “This is important, as it has implications for other family members and treatment choices alike. Also important to note is that where this study enrolled men who had already been treated with chemotherapy and/or abiraterone, future research will likely move the enzalutamide/talazoparib combination — or components of it — to earlier disease stages.”

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