Why Do I Still Smell After Showering?

It’s 11 a.m. You showered at seven, soaped everything twice, swiped on deodorant. Then you reach for a mug on the top shelf and catch it, a sour, oniony note coming off your own armpit.

The smell comes from bacteria, not from sweat

Cleveland Clinic¹ puts it in one sentence: body odor is what you smell when your sweat comes in contact with the bacteria on your skin.

You have two kinds of sweat glands. Eccrine glands handle cooling, and their sweat has no odor of its own. Apocrine glands open into hair follicles in your armpits and groin, and they switch on at puberty, which is why small kids don’t have body odor. Their sweat is the kind that smells once bacteria get to it.

So who are the bacteria? The American Society for Microbiology² names three common groups of skin bacteria that produce body odor: Corynebacterium, Staphylococcus and Cutibacterium. Some Corynebacterium species make fatty acids described as goat-like, others one described as cumin-like. Staphylococcus hominis makes a compound that smells like rotten onions or meat.

That’s your 11 a.m. onion. Not a dirty body. A bacterium doing its job.

A shower rinses off sweat and some of the bacteria. It does nothing to the glands. Does the shower help? Yes. Does it settle things for the day? No, because the glands keep sending sweat out and whatever bacteria stayed behind get to work on it.

Your shirt is a suspect

Clean armpits go into a shirt, and the shirt matters more than most of us assume.

In a 2014 study in Applied and Environmental Microbiology³, researchers collected T-shirts from 26 healthy people after an intense spinning session and incubated them for 28 hours. The polyester shirts smelled significantly less pleasant and more intense than the cotton ones. Micrococci, a type of skin bacteria, turned up on almost every synthetic shirt and almost only on synthetic shirts.

That study used workout shirts, so it can’t speak for your work blouse or your washing machine. It does line up with what clinicians tell people who sweat a lot. The American Academy of Dermatology⁴ recommends breathable fabrics like cotton, and the NHS⁵ advises avoiding synthetic materials such as nylon.

Run the test on your own closet. If the same top smells by lunch every time you wear it, trust your nose over the tag.

What else turns the volume up

Cleveland Clinic¹ lists a few things that change how you smell. Sulfur-rich foods like onions, garlic, cabbage and red meat are on it. So are the foods and drinks that make you sweat more: caffeine, spicy food, alcohol and MSG.

Hormones count too. Cleveland Clinic¹ says changes in hormones can change body odor, and it points to menopause, when sweating can get heavy. Stress, hot weather, exercise and genetics round out the list.

If you can’t tell which of these is yours, the AAD⁴ suggests a sweat journal. Write down when it happens and what came before. Heat, spicy food, caffeine, alcohol, anxiety and stress are the usual triggers.

Antiperspirant and deodorant do different jobs

Most of us grab one stick and expect it to do both. It can’t.

An antiperspirant contains aluminum salts, which cut the flow of sweat by restricting access to the upper part of the sweat gland. A deodorant doesn’t touch sweat. It uses ingredients like alcohol to neutralize odor-causing bacteria and fragrance to cover what’s left.

And the timing is probably backwards in your routine. Most of us apply in the morning, skin still damp from the shower, on the way out the door. Cleveland Clinic⁶ says night is better, when your sweating is at a minimum, because the product then stays in place for six to eight hours. Put it on clean, dry skin, and not right after shaving, which can irritate. Deodorant goes on in the morning for whatever odor is left. The AAD⁴ gives the same order for prescription antiperspirants: before bed on dry skin, with deodorant after you wake up.

The play

Try this: swap the order tonight

Wash your underarms at night and dry them completely.

Apply antiperspirant to the dry skin before bed.

In the morning, add deodorant.

One catch. In the ASM’s² summary of the research, antiperspirant use led to an increase in odor-producing Actinobacteria in some people, and antimicrobial products changed the mix of bacteria on the skin. So a product that cuts your sweat can still leave the smell behind. If that’s you, the NHS⁵ says a pharmacist can recommend a stronger antiperspirant.

Worried about the aluminum? Cleveland Clinic⁶ says research hasn’t shown that aluminum causes breast cancer.

Daily bathing and shaving the armpits are also on Cleveland Clinic’s⁶ list for cutting odor. Shaving is your call, not a requirement.

When the smell itself changes

Most body odor is bacteria plus sweat. Some of it is information.

Cleveland Clinic¹ says to contact a provider about a fruity body odor, a bleach-like body odor, or a sudden change in how much you sweat. It ties a fruity smell to diabetes, specifically ketoacidosis, and a bleach-like one to liver or kidney disease.

A fishy smell from your sweat, urine and breath can come from trimethylaminuria. MedlinePlus Genetics⁷ describes it as an uncommon genetic disorder in which the body can’t break down a compound called trimethylamine. It also notes that temporary symptoms have been reported in some healthy women at the start of menstruation. A fishy smell from the vagina is a different question, and our article on what causes vaginal odor covers it.

When to get checked

Don’t wait if

1. Emergency

   If you have diabetes and a fruity smell on your breath comes with nausea and vomiting, trouble breathing, or drowsiness and confusion, call 911 or your local emergency number. MedlinePlus⁸ calls diabetic ketoacidosis a medical emergency.

See a clinician if any of these fit:

• A fruity or bleach-like body odor that is new for you
• A fishy odor that follows you through sweat, urine or breath
• A sudden change in how much you sweat
• Sweating that has gone on for at least 6 months, happens at least once a week, or gets in the way of daily life, which the NHS⁵ lists among its reasons to see a GP
• Night sweats

Back to that mug on the top shelf. Next time you catch it at 11 a.m., check the shirt before you blame the shower.