Body odor happens when bacteria on your skin break down the proteins and fats in your sweat into smelly compounds. The sweat itself is almost odorless. That means the key to stopping mustiness is targeting the bacteria, managing moisture, and addressing a few overlooked factors like clothing and diet that keep the smell coming back even after you shower.
Why You Smell: Bacteria, Not Sweat
Your body has two types of sweat glands. The ones that activate during puberty, concentrated in your armpits, groin, and scalp, secrete an oily fluid made of proteins, lipids, and steroids. This fluid has almost no scent on its own. The smell starts when skin bacteria, primarily species of Corynebacterium and Staphylococcus, feed on those secretions and release volatile byproducts.
Different bacteria produce different smells. Corynebacterium species break down sweat into fatty acids that give off a sharp, cumin-like or goat-like odor. Staphylococcus hominis produces a thioalcohol compound responsible for that rotten-onion or meaty underarm smell. On your feet, Staphylococcus epidermidis breaks down the amino acid leucine into isovaleric acid, which is why feet tend to smell cheesy rather than just sweaty. Understanding this helps explain why simply rinsing with water isn’t always enough. You need to actually reduce the bacterial population on your skin.
Upgrade Your Washing Routine
A quick pass with a bar of soap doesn’t always cut it, especially in areas with dense sweat glands. Focus your cleaning on armpits, groin folds, behind your ears, and feet. Use a washcloth or loofah to physically remove the film of bacteria and dead skin cells, not just wet the surface. Let soap or body wash sit on these areas for 30 to 60 seconds before rinsing so it has time to work.
If regular soap isn’t solving the problem, a body wash containing benzoyl peroxide can significantly reduce the bacterial load on your skin. Dermatologists at Baylor College of Medicine recommend starting with a low concentration and increasing gradually based on how your skin responds. A wash-off product (like a body wash) is less irritating than a leave-on gel. Use it on your armpits and other odor-prone areas in the shower, following the product label for frequency. This approach is particularly effective for people who notice persistent odor even with daily showering.
Your Clothes Might Be the Problem
If you shower thoroughly but still smell musty partway through the day, your clothing is a likely culprit. Research published in the journal Applied and Environmental Microbiology found that polyester shirts smelled significantly more intense, more musty, more sweaty, and more sour than cotton shirts after the same workout. The difference was dramatic.
Two things explain this. First, polyester is a petroleum-based fiber with poor odor-absorbing capacity. Smelly compounds sit on the surface and waft into the air instead of being trapped. Cotton, made of cellulose, actively absorbs both moisture and odor molecules. Second, odor-causing Micrococcus bacteria grow far better on synthetic fabrics. Researchers found bacterial counts on polyester reached up to 17.2 million colony-forming units per square centimeter, roughly ten times more growth than on other textiles. The aerobic conditions on polyester’s smooth surface create an ideal environment for these bacteria.
The practical fix: wear natural fibers like cotton, linen, or merino wool against your skin whenever possible, especially for undershirts and underwear. If you exercise in synthetics, wash them promptly. Don’t let sweaty gym clothes sit balled up in a hamper for days, as that gives bacteria time to build up in the fabric.
Washing Clothes That Already Smell
Sometimes clothing develops a persistent musty smell that survives a normal wash cycle. This happens because bacteria and body oils form a thin biofilm on fabric fibers, particularly in synthetics. A regular cold-water wash with mild detergent may not fully break it down.
To reset smelly clothes, use a detergent that contains lipase enzymes, which specifically target the fatty residues from skin oils and sebum that feed odor-causing bacteria. Washing in warm or hot water (when the fabric allows it) also helps. For stubborn odor, soaking garments in a solution of white vinegar or oxygen-based bleach before washing can break apart bacterial buildup. Some people find that adding a half cup of baking soda to the wash cycle neutralizes lingering smells. If a garment still smells musty after washing and drying, the biofilm is likely established deep in the fibers, and it may be time to replace it.
Antiperspirants vs. Deodorants
These two products do completely different things. Deodorant masks or neutralizes odor, often with fragrance and sometimes with antibacterial ingredients. Antiperspirant actually reduces how much you sweat by using aluminum-based compounds that temporarily plug sweat ducts. Clinical studies show that over-the-counter clinical-strength antiperspirants can reduce sweat rate substantially, outperforming even prescription-strength aluminum chloride products in some trials while causing less skin irritation.
For best results, apply antiperspirant at night before bed, not in the morning. Your sweat glands are less active while you sleep, which gives the aluminum compounds time to form a more effective barrier in the sweat ducts. The protection carries over into the next day even after you shower. If a standard-strength product isn’t working, try a clinical-strength version before jumping to a prescription.
Trim or Remove Body Hair
Hair in your armpits and groin creates more surface area for bacteria to cling to and traps moisture against your skin, slowing evaporation. Trimming or shaving these areas reduces the warm, damp environment bacteria thrive in. You don’t necessarily need to shave completely. Even trimming hair short with clippers can make a noticeable difference in how quickly odor develops and how well your antiperspirant or deodorant makes contact with skin.
Foods That Make You Smell Worse
What you eat directly affects your body odor. Cruciferous vegetables like broccoli, cauliflower, cabbage, and kale are high in sulfur-containing compounds. When your body breaks them down, they produce hydrogen sulfide, which smells like rotten eggs. This doesn’t mean you should avoid these nutritious foods entirely, but if you’re dealing with persistent odor, eating large portions of them daily could be a contributing factor.
Garlic, onions, cumin, and curry also produce sulfur-like compounds during digestion. These show up on your breath and react with sweat on your skin to amplify body odor. The effect can last for a day or two after a heavy meal. If you have an important event coming up, scaling back on these foods for 24 to 48 hours beforehand can help.
When Odor Signals Something Medical
Most body odor is a hygiene and lifestyle issue, but certain persistent or unusual smells can point to an underlying condition. A fruity or acetone-like body odor or breath can be a sign of diabetic ketoacidosis, a serious complication of diabetes where the body starts breaking down fat for fuel and produces ketones.
A persistent fishy smell that doesn’t respond to any hygiene measures could indicate trimethylaminuria, a metabolic condition where the body can’t properly break down a compound called trimethylamine. It builds up and gets released through sweat, breath, and urine. The condition is genetic in most cases, caused by mutations in a liver enzyme. Diagnosis requires a urine test after eating a marine fish meal, measuring how efficiently your body processes the compound. Unaffected people convert more than 92% of the compound to its odorless form, while affected individuals fall below 84%. If you suspect this, a doctor can order the specific urine test.
An ammonia-like smell in sweat can sometimes indicate kidney issues or simply that you’re eating a very high-protein diet and your body is excreting excess nitrogen through sweat. Persistent changes in body odor that don’t respond to the strategies above are worth bringing up with a healthcare provider, as they can sometimes be the first noticeable sign of a metabolic problem.
A Daily Routine That Works
Putting it all together, here’s what a practical anti-odor routine looks like:
- Shower daily with attention to odor-prone areas, using a washcloth and letting soap sit for at least 30 seconds before rinsing
- Apply antiperspirant at night to clean, dry underarms for maximum effectiveness
- Wear natural fabrics against your skin, especially cotton or merino wool undershirts and underwear
- Trim body hair in your armpits and groin to reduce bacterial surface area
- Wash workout clothes promptly with enzyme-based detergent, and don’t re-wear synthetics without washing
- Keep a travel-size deodorant or body wipe for midday touch-ups if needed
If this baseline routine doesn’t solve the problem after two to three consistent weeks, adding a benzoyl peroxide wash for your underarms and other problem areas is the next step. Most people find that the combination of reducing bacteria on their skin and switching away from synthetic fabrics eliminates the issue entirely.