9 Surprising Things Sweat Can Reveal About Your Health
- Tracy Middleton
- Fact-checked by Joy Ferguson
- July 18, 2022
You probably don’t give sweat much thought until you’re mopping it off your brow mid-workout or scrubbing pit stains out of a polo. You should. Because sweating is good for you—and it can reveal a lot about your health.
“Sweating is one of humans’ biggest superpowers,” says Andrew Best, Ph.D., an assistant professor of Biology at the Massachusetts College of Liberal Arts who has extensively studied sweat. “From an evolutionary perspective, it’s as important as big brains, walking on two legs, and developing language and culture. without the ability to sweat we’d be completely incapacitated in warm—not even hot—weather.”
Beyond being one the primary ways to cool the body, sweating also aids electrolyte regulation, removes wastes and some medications, and helps hydrate the skin, says Cameron West, M.D., FAAD, a dermatologist with U.S. Dermatology Partners Wichita.
Sweat has been hailed as one of the next generation of digital biomarkers (1) and people are flocking to urban sweat lodges like Shape House to perspire under far-infared light—light we can’t see, but can feel as radiant heat—in the name of good health. Soon, sweat sensors on wearables or sewn into athletic clothing may be able to tell you what’s happening in your nervous system, your immune system, and more (2).
“Sweat has a story about what is going on in the human body,” says Ray Runyon, Ph.D., an analytical chemist who runs Stress Challenge, Sweat Collection, Stress Correlation, a sweat biomarker lab at the University of Arizona Andrew Weil Center for Integrative Medicine. The lab’s research is informing teams of researchers and engineers who are developing devices that would measure different molecules in sweat—including cortisol and adrenaline—to monitor your health in real-time. “What we measure in sweat can complement other things we measure in the body to tell us more about our health, wellbeing, and performance.”
Even brands like Gatorade are getting in on the game; the sports drink manufacturer’s GX Sweat Patch pulls data from your perspiration, including data to estimate how much liquid poured out of your pores and how much sodium you lost, then suggests how to replenish your stores (we suspect Gatorade is involved).
With sweat so under the microscope, we asked experts to share the physical, mental, and emotional benefits of sweating.
1. Regulates Your Body Temperature
Arguably the biggest benefit of sweating is that it keeps you cool. Humans developed more sweat glands as a mechanism for cooling, which was important when we were covering great distances to forage in the heat, says Best. “We can do more in the heat, like running, than most animals because we’re covered in eccrine glands.”
Eccrine sweat glands pump out the sweat you notice during a tough workout. Predominantly made from water, this type of sweat floods out of millions of eccrine glands across your skin’s surface to help you cool down. (Apocrine glands in the armpits and groin are different; they produce the oilier sweat that, when it comes into contact with bacteria on your skin, takes on that unmistakable odor of locker rooms everywhere.)
When you work your muscles—or just step out into the sun on a hot day—your core body temperature rises, says Best. Eccrine sweat glands act as an internal AC system to help you cool off by transporting sweat to the surface of your skin, where it evaporates and cools the skin, reducing your inner body temperature.
2. Amps Your Workout Performance
Sweating in and of itself won’t help you build muscle. But your internal sprinkler system can boost your athletic performance.
The better your body gets at sweating, the cooler you can keep your core temperature during a workout, and the longer and harder you can go, says Best.
The good news: You can train your body to sweat more to dump heat. “The amount you sweat is super trainable, more than people realize,” says Best. In a PLOS ONE study (3), when long-distance runners engaged in cycling sessions, they got sweatier sooner than their sedentary peers. They also activated more sweat glands, resulting in a more profuse outpouring than their non-active counterparts.
Previous research found that subjects who participated in aerobic training four times a week for eight weeks, either on an exercise bike or running on a treadmill, improved their fitness an average of 19 percent and their sweating capacity by an average of 38 percent (4).
3. Boosts Heart Health
The benefits of sweating extend to your ticker. Sweating—whether it’s because you’re training for a half marathon or sitting in a sauna—may reduce your risk of cardiovascular problems. A study published in 2015 followed Finnish men for 20 years and found that those who frequently sweated in a sauna were less likely to develop fatal coronary heart disease or to die from any cause during the course of the study (5). In a follow-up to the study, researchers found that the risk for developing high blood pressure was significantly lower in the subjects who enjoyed a sauna 4-7 times a week compared to those who had a sauna only once a week.
The authors suggest a number of potential mechanisms to explain why regular sauna bathing may have beneficial effects. One is that when your body temperature spikes and you sweat, it removes fluid from the body. Another is the function of the endothelial—the inside layer of blood vessels—is strengthened. Both of which can help lower blood pressure, according to the study authors
4. Increases Immunity and Prevents Infections
The elevated body temperature that happens when you sweat can help your body kill pathogens and helps immune cells work better, according to 2020 research in the journal Evolution, Medicine, and Public Health (6).
Sweat is also your own personal sanitizer. It contains a natural germ-killing peptide—a molecule made up of amino acids—called dermcidin, which can help protect against germs and bacteria that can cause disease. Some studies suggest, that in the long-term, dermcidin may be even better at killing germs than traditional antibiotics (7).
5. Reveals Hidden Illness
Sweating buckets may be a red flag for a more serious health condition. Hyperhidrosis—aka excessive, uncontrollable sweating—may be linked to thyroid problems, cancers including leukemia and lymphoma, diabetes, and infections, according to the Mayo Clinic.
If you sweat profusely even when sitting in a cool room or wake up with drenched sheets from night sweats, talk to your doctor. Medications, Botox injections, or a type of electrotherapy called iontophoresis may help you stay dry.
6. Lifts Your Mood
During a sweaty workout, your body releases endorphins and dopamine—the feel-good hormones that are behind a runner’s high. But that’s not the only connection between sweat and mood.
Being sweaty can actually make people around you feel happier, according to one study (8). Researchers asked men to watch video clips that would make them feel happy, afraid, or neutral. Afterward, they collected sweat samples from the men and then exposed a second group of subjects to the sweat samples. The result: Sniffers of “happy” sweat exhibited traits of happiness themselves.
7. Hydrates Your Skin
The benefits of sweating of course extend to your skin. “While we tend to think of sweat as just salty water, its contents include sugar, glucose, various electrolytes, amino acids, and substances that help hydrate the skin such as urea and lactate, says West (9). Sodium, potassium, urea, and lactate act together as humectants for your skin, says Zain Husain, M.D., FAAD, a board-certified dermatologist in Marlboro New Jersey. These natural moistening factors (NMFs) are so powerful that they’re often added to products to treat dry skin (10).
“Humectants attract and bind moisture from the surrounding atmosphere and draw it into the skin,” Husain explains. This helps keep pathogens from entering your body. It also prevents water loss through your skin. If your skin gets too parched, it can’t perform these vital functions.
8. Eliminates Some Toxins
The bulk of your body’s detoxification is done by your kidneys, which filter toxins out of the blood into your urine, says Best. “Anything in your blood comes out in your sweat, but sweating doesn’t detoxify your body the way that some hot yoga devotees claim.”
However, a small study (11) published in the International Journal of Environmental Research and Public Health, found that varying amounts of toxic metals including nickel, lead, copper, arsenic, and mercury left the body when subjects sweated. An earlier study (12) found their subject’s sweat samples contained phthalates found in a range of everyday items such as cooking utensils and paint.
9. Zaps Zits
When you sweat, your pores open up and release the gunk trapped inside them. “The mixture of oils and cells that have accumulated within pores is exposed to the environment and oxidizes,” says Husain. On the other hand, prolonged exposure to sweat can worsen acne and folliculitis, says West. “This is particularly the case when you remain in sweaty workout clothes post-workout, allowing bacteria to proliferate on the skin, clog pores, and worsen acne.” Your move: shower and change clothes after your gym session. Pick a product that includes benzoyl peroxide, salicylic acid, azelaic acid, or adapalene. “Dermatologists often recommend brands like Neutrogena, La Roche-Posay, CeraVe, and SkinCeuticals,” Husain adds. “And don’t forget to moisturize and apply sunscreen daily, as dry and sun-exposed skin is more prone to breakouts.”
References
1. Brasier N, et al (2019). Sweat as a Source of Next-Generation Digital Biomarkers. Digit Biomark.
2. Terse-Thakoor, T. et al (2020). Thread-based multiplexed sensor patch for real-time sweat monitoring.
3. Lee JB, et al (2014). Long distance runners present upregulated sweating responses than sedentary counterparts.
4. Wilson TE, et al (2010). Aerobic training improves in vivo cholinergic responsiveness but not sensitivity of eccrine sweat glands.
5. Laukkanen T, et al (2015). Association Between Sauna Bathing and Fatal Cardiovascular and All-Cause Mortality Events.
6. Wrotek S, et al (2020). Let fever do its job: The meaning of fever in the pandemic era.
7. Rieg S, et al (2014). Expression of the sweat-derived innate defence antimicrobial peptide dermcidin is not impaired in Staphylococcus aureus colonization or recurrent skin infections.
8. de Groot JH, et al (2015). A sniff of happiness.
9. Watabe A, et al (2013). Sweat constitutes several natural moisturizing factors, lactate, urea, sodium, and potassium.
10. Parker J, et al (2017). Moisturisers for the treatment of foot xerosis: a systematic review.
11. Kuan WH, et al (2022). Excretion of Ni, Pb, Cu, As, and Hg in Sweat under Two Sweating Conditions.
12. Genuis SJ, et al (2012). Human elimination of phthalate compounds: blood, urine, and sweat (BUS) study.
