Sweat Much? The Truth About That Smell

Sure, it’s satisfying to wring out your sports bra after a SoulCycle class. But, outside of a workout, being sweaty is more often unpleasant than a sign of success. So, we spoke to people who are in the business of sweat to find out what’s really going on — and what you can do about it. Ahead, surprising facts, information, and solutions about perspiration. Sweat school is now in session.

Before running water and indoor toilets were common, we didn’t take much issue with our neighbors’ stench. But, in the late 1800s, we started to understand more about germs and disease, and regular bathing became a daily ritual. In 1888, Mum — the world's first deodorant — was trademarked. The first antiperspirant, Everdry, followed shortly in 1903, but neither caught on. Most people wore fabric shields in their clothing to absorb sweat or just hoped perfume would mask any odor.

That all changed in the summer of 1912 when, according to the Smithsonian, Edna Murphey set up a booth at an expo to sell her antiperspirant, Odorono — a spray that her father, a surgeon, had created to keep doctors’ hands dry while operating. Despite some initial interest, she was selling a product most people didn’t want — bodily fluids and functions were a taboo topic. So, Murphey hired an advertising agency who tackled the sales problem by convincing potential customers that perspiring was embarrassing. The advertising campaign created, and then preyed upon, fears that women were cluelessly offending potential suitors with their body odor, causing interest to skyrocket.

Sweat is a lifesaver — a too-high internal body temperature can send our organs into shut-down mode, explains Susan Biehle-Hulette, PhD, a biochemist at Procter & Gamble (the makers of Secret and Old Spice). “[Sweating] is the body's primary method of thermoregulation,” she says.

When we experience stressors like heat, anxiety, or pain, the sympathetic nervous system (the part of the brain responsible for the “fight or flight” response) releases a neurotransmitter called acetylcholine, which stimulates the nerves that control our two- to four-million sweat glands, instructing them to release sweat.

The body has different kinds of sweat glands, and most common are the eccrine and the apocrine. “Eccrine sweat glands cover most of the body and are stimulated by activity or temperature,” says David Pariser, MD, a professor of dermatology at the Eastern Virginia Medical School in Norfolk, Virginia. As your sweat evaporates, your skin cools to keep your body at an optimal temperature, which really seems preferable to panting like a dog.

Apocrine glands — which are typically found on the palms, feet, and axilla (the area under your arms) — are typically activated when you become emotionally stressed (think sweating it out during a stressful work presentation). This kind of sweating occurs regardless of the temperature and is thought to have evolved to assist in gripping and running during the quick, stressful escapes of our ancestors from predation. While apocrine glands are active on the palms and feet of babies, they don't appear under the arms or in the pubic area until the onset of puberty, leading to a belief that they play a pheromone-like role in sexual attraction. A third type of sweat gland, the apoeccrine gland, has some qualities of both eccrine and apocrine.

Sweat might not be so bad if it weren’t for the odor, right? Well, don’t blame sweat for the stink. “Sweat itself doesn’t smell,” Biehle-Hulette explains. The odor actually comes from the byproducts of bacteria that feed on components of your sweat.

“The watery sweat that comes out of the eccrine gland is colorless and odorless,” says Dr. Pariser. This isn't the sweat you have to worry about when it comes to your personal BO. Because, while there are fewer apocrine glands than eccrine, it's these guys that are responsible for perspiration's smelly reputation. “Apocrine sweat is oily and cloudy,” Dr. Pariser says. “These glands are found in the underarms, under the breasts, and in the groin area.”

Eccrine sweat is mostly water, so there’s not much "food" for bacteria. But, apocrine sweat contains 20 percent lipids and proteins, Biehle-Hulette says, making it an ideal feeding ground for the microbes. There are various bacterial types that act on various molecules to form a wide array of byproducts, each stinky in their own special way. For example, members of the Staphylococcus genus (commonly referred to as "Staph" bacteria) enjoy feeding on glycylcysteinyl-S-conjugate (a molecule in your sweat). The byproduct of this is 3-Sulfanylhexan-1-ol, a sulfurous compound that helps give sweat its special, onion-y scent. Other sweat molecules and bacteria work together to create scents ranging from "goat-like" to "cheesy."

Here’s the real injustice: Some people lack the genes to produce body odor. Scientists discovered that people who lack a specific gene (the ABCC11 gene) don't produce an important chemical within their sweat that bacteria feed on. Thus, the smell-creating bacteria can't break it down into odoriferous compounds.

There are two main types of products found in the beauty aisle: Deodorants, which cover up body odor, and antiperspirants, which prevent sweat by blocking the glands that release it.

Aluminum salts are the most common active ingredient in antiperspirants, says Ni’Kita Wilson, CEO of Catalyst Cosmetic Development. “The aluminum ions penetrate the sweat glands and bond with water, which creates a sort of plug that prevents sweating.” But, you've probably heard talk of the potential health dangers of the ingredient. While the National Cancer Institute “[is] not aware of any conclusive evidence linking the use of underarm antiperspirants or deodorants and the subsequent development of breast cancer,” they say that studies have shown conflicting results and additional research is needed.

For the best results, take consistency and timing into account. “The antiperspirants with a creamy texture will work better than an aerosol, roll-on, solid, or gel,” says DeeAnna Glaser, MD, president of the International Hyperhidrosis Society and vice chairman of the St. Louis University department of dermatology. “The semi-solid vehicle makes it easier to carry the aluminum salts into the sweat duct,” she explains. And, for the antiperspirant to work effectively, it must be absorbed by your sweat duct — due to body temperature fluctuations, the best time to apply your sweat-stopper is before bed, Dr. Glaser explains.

Natural options have been increasing in popularity, and they use starch or talc to absorb moisture. But, if drugstore products don’t cut it, check in with your doctor, because overacting sweat glands may be the issue. Hyperhidrosis is a medical condition that causes excessive sweating around the head, armpits, hands, and feet. Clinical-strength antiperspirants are often recommended, and if the situation is severe enough, doctors can inject Botox in the armpits to prevent sweating. “Botox prevents the nerve that controls the sweat gland from sending a signal,” Dr. Glaser says. The injections last for six to nine months and can cost anywhere from $1,000 to $2,000 a visit.

Another option, MiraDry, uses “microwave energy” to eliminate your sweat glands. “It targets the water in the glands and heats them up until they are destroyed,” Dr. Glaser says. While the outpatient procedure is FDA-approved and has seen positive results in a company-funded study, the long-term effects of the relatively new treatment have not yet been determined.

The moral of the story? Everybody poops; everybody perspires. It's a (slightly) dirty business, but with all the science and solutions out there, there's no reason to sweat the small stuff.