You showered. Your deodorant is doing its job. Then you warm up, and your shirt smells like the last time you wore it. If that sounds familiar, the problem may not be you. It may be the shirt. Researchers have studied this more than you might think, and what they found points to a few simple fixes.
Polyester Holds On to Body Odor
In a 2014 study in Applied and Environmental Microbiology, 26 people did an hour-long spin class in cotton, polyester, or blended shirts. The shirts were then left for 28 hours, and a trained odor panel rated the polyester shirts as smelling less pleasant and more intense than the cotton ones. The researchers also found odor-causing bacteria called micrococci on almost all of the synthetic shirts, and hardly any on the cotton ones.
Washing helps, but it does not always finish the job. University of Alberta researchers tested cotton and polyester fabrics worn under the arms through repeated rounds of wearing and washing. In their 2014 study, washing cut odor and bacteria on both fabrics. But polyester smelled stronger after wear, before washing and after it, even though both fabrics carried about the same amount of bacteria.
A 2020 study from the same university helps explain why. Smelly compounds like the ones in sweat are more attracted to polyester than to cotton, and they do not completely wash out, so they can build up with each wear. Polyester repels water, which is why it dries so fast, but it naturally attracts the oils from your skin. The researchers' advice was simple: if body odor is a concern, choose cotton.
So-called anti-odor fabrics are not a sure fix either. In the same team's wear tests, they smelled just as strong as untreated fabrics, according to the University of Alberta.
Why You Might Notice It More After Switching
If you recently switched from antiperspirant to natural deodorant, you may be noticing your shirts for the first time. Antiperspirant uses aluminum to cut down how much moisture reaches your shirt. Deodorant works on odor instead, which we explain in our guide to deodorant vs. antiperspirant. That means fabric matters more than it used to. A shirt that smells as soon as you warm up can be the fabric holding on to old odor, not your deodorant giving out.
How to Get B.O. Out of a Shirt
- Do not let sweaty clothes sit. Consumer Reports notes that leaving synthetics bunched up and damp helps bacteria grow. If you cannot wash a shirt right away, hang it up to air dry instead of balling it up in the hamper, which Maytag recommends too.
- Turn it inside out. That puts the side that touched your skin, where the oils and odor are, in direct contact with the water and detergent.
- Pre-treat the underarms. Maytag suggests rubbing a paste of baking soda and water into the underarms and letting it sit for 30 minutes. For stubborn smells, it suggests soaking the shirt for 30 minutes in one cup of white vinegar mixed with four cups of warm water, then rinsing it before it goes in the washer. Skip the vinegar on delicates and on anything with elastic. Never mix vinegar with chlorine bleach, because together they release chlorine gas, the New Jersey Department of Health warns.
- Follow the care label on water temperature. Maytag suggests warm or hot water for cotton and cold water for synthetics. An enzyme detergent helps either way. Enzymes break down specific soils, including protein soils like bodily fluids, and they work without needing hot water, according to Michigan State University.
- Measure the detergent and skip the fabric softener on synthetics. Too little detergent can leave odor behind, and too much can leave residue, Maytag says. Nike warns that fabric softener leaves a residue on workout clothes that odor-causing bacteria stick to, and Consumer Reports says softener can clog the fabric's pores.
- Smell it before it goes in the dryer. If the underarms still smell while the shirt is wet, wash it again. Consumer Reports and Maytag both note that dryer heat can set any odor that is still there. Let shirts dry all the way before you put them away.
How to Keep It From Coming Back
- Wear cotton next to your skin when you can. The research above points the same way, and the Cleveland Clinic recommends loose cotton clothing, including underwear and bras, for body odor. If you love a polyester workout top, the Ghent University researchers behind the spin class study suggested clothes with cotton where the fabric touches the underarms, Popular Science reported.
- Go light on deodorant and let it set. Two or three swipes are plenty. Give it a minute before your shirt goes on, so it stays on your skin instead of the fabric. Our deodorant stain guide covers the marks side of things.
- Know when to let a shirt go. If an old polyester shirt still smells after a good soak and wash, the odor may be built into the fibers. It might be time to retire it.
Frequently Asked Questions
Why do my clothes smell like B.O. after washing?
Smelly compounds from sweat bind to some fabrics, especially polyester, and do not fully wash out. University of Alberta research found they can build up over repeated wears.
Does cotton or polyester hold more body odor?
Polyester. In the studies above, polyester smelled stronger than cotton after wear, and it held on to more odor after washing.
Is it my deodorant or my shirt?
Smell your underarm, then smell your shirt. If you smell fine and the shirt does not, the shirt is holding on to old odor. Pre-treat it and wash it using the steps above.
Does vinegar get rid of body odor in clothes?
A white vinegar soak before washing is a common fix, and Maytag recommends it for stubborn smells. Skip it on delicates and anything with elastic, rinse before washing, and never mix it with chlorine bleach.
The Frank Bottom Line
If a clean shirt smells as soon as you warm up, the fabric may be holding on to old odor. Wash sweaty clothes soon, turn them inside out, pre-treat the underarms, skip the softener on synthetics, and wear cotton next to your skin when you can. Then take care of the skin side with a deodorant made to control odor. Try our extra strength baking soda stick, or our baking soda free stick if your skin is sensitive.
