How to Get Smell Out of Clothes
The smell is bacteria, not sweat. Sweat is almost odourless — bacteria metabolise it into volatile fatty acids. Cold washing leaves bacterial biofilm intact.
Never use vinegar and baking soda together in the same wash — the acid-base reaction neutralises both and leaves neither effective. Use them in separate steps.
Bacterial Biofilm — Why Clothes Still Smell After Washing
Persistent fabric odour is almost never caused by sweat itself. Fresh sweat is a mixture of water (99%), sodium chloride, urea, lactic acid, urocanic acid, and small amounts of amino acids and proteins — most of these compounds are essentially odourless. The distinctive smell that develops on unwashed clothing comes from bacterial metabolism. Human skin carries a diverse bacterial microbiome, dominated by species from the Corynebacterium, Staphylococcus, and Cutibacterium genera. These bacteria consume the compounds in sweat as nutrients and produce volatile organic compounds (VOCs) as metabolic by-products. The VOCs responsible for body odour include short-chain fatty acids (butyric acid — the characteristic rancid/vomit smell, valeric acid, caproic acid), steroid-derived compounds (androsterone, which has a musk-like scent), and sulphur-containing compounds from the breakdown of sulphur-containing amino acids like cysteine. These VOCs are absorbed into fabric fibres and are responsible for the smell that persists in clothing after wearing. The reason odour persists even after washing is bacterial biofilm. Bacteria that colonise fabric do not remain as free-floating (planktonic) cells in the wash water — they form biofilms, which are structured microbial communities embedded in a self-produced polysaccharide and protein matrix. Biofilms are mechanically stable and significantly more resistant to detergents, acids, and antimicrobial agents than individual bacteria cells. A 30°C wash cycle removes a proportion of surface bacteria but leaves established biofilm colonies largely intact within the fibre structure. This is particularly pronounced in synthetic fibres: polyester and nylon fibres are hydrophobic and have large surface areas for bacterial adhesion. The waxy cuticle of cotton fibres is more resistant to bacteria colonisation than the irregular surfaces of synthetic fibres, which is why polyester and nylon gym clothes tend to develop persistent odour faster than cotton equivalents. Acid treatment (white vinegar — 5% acetic acid, or citric acid solution) disrupts the polysaccharide biofilm matrix through acid hydrolysis and lowers the pH below the optimal range for most textile-associated bacteria (typically 6.5–7.5). This makes bacteria more susceptible to subsequent washing. Sodium bicarbonate (baking soda) is alkaline and provides a different mechanism — it adsorbs volatile fatty acid molecules directly onto the bicarbonate surface and neutralises the acid odour compounds chemically, while also being mildly bacteriostatic. UV radiation from sunlight is directly bactericidal — UV-B (280–315 nm) damages bacterial DNA (creating thymine dimers) and kills or inactivates surface bacteria effectively. Air drying in direct sunlight after treatment is not a substitute for chemical treatment but provides a useful additional bactericidal step. Odour-masking products like Febreze use β-cyclodextrin molecules — a ring-shaped sugar polymer that traps volatile odour molecules inside its hydrophobic interior. This temporarily removes the odour molecules from the gas phase (so you cannot smell them), but does not kill the bacteria or remove the odour compounds from the fabric permanently. The smell returns as new volatile compounds are generated.
Treatment Steps
Identify the odour type — this determines the treatment
Musty/earthy smell: mould or mildew in the fabric (see mould guide). Rancid/sour smell from armpit/collar area: bacterial volatile fatty acid production from sweat. Smoke smell: aromatic compounds adsorbed from combustion. Chemical smell: synthetic fabric off-gassing or finishing chemicals. Persistent body odour that returns after washing: bacterial biofilm in fabric. This guide covers bacterial biofilm-based odour — the most common persistent smell problem.
Pre-soak in white vinegar solution — disrupts bacterial biofilm
Fill a basin with cool water and add 200–250ml of undiluted white vinegar (5% acetic acid). Submerge the garment completely and soak for 30–60 minutes. The acetic acid lowers the pH within the fabric and hydrolyses the polysaccharide biofilm matrix, making the bacterial colonies more susceptible to mechanical removal during washing. For heavy gym-clothes odour, soak for 2–3 hours or overnight. Do not dilute further — the effectiveness decreases significantly below 2% acetic acid concentration. The vinegar smell will fully dissipate in the wash and during drying.
Add baking soda to the drum — adsorbs volatile fatty acids
Add 3–4 tablespoons of sodium bicarbonate (baking soda) to the washing machine drum directly (not in the detergent drawer). Sodium bicarbonate has two functions: it adsorbs volatile fatty acid molecules onto its surface and neutralises acid odour compounds chemically, AND it acts as a mild bacteriostatic agent. Do not add baking soda and vinegar to the same wash at the same time — the acid-base neutralisation reaction converts them both to water and carbon dioxide, leaving neither effective. The vinegar pre-soak is separate from the baking soda in the machine wash.
Wash at the highest safe temperature with enzyme detergent
For 100% cotton: wash at 60°C — this temperature kills most textile-associated bacteria and allows enzyme detergents (lipase, protease) to break down the fatty acid and protein residues that bacteria feed on. For synthetic fabrics (polyester, nylon): most cannot be washed above 40°C. Use a biological enzyme detergent at 40°C, which is effective against the odour substrates even if it does not kill all the bacteria. For synthetic gym clothes with entrenched odour: repeat the vinegar pre-soak + 40°C wash cycle 2–3 times to progressively erode the biofilm.
Air dry in direct sunlight if possible
UV radiation in direct sunlight kills surface bacteria and inactivates residual spores. Hang the garment in direct sun for at least 1–2 hours. Even overcast daylight has some UV bactericidal effect. Avoid drying in an enclosed, damp space — this allows any residual bacteria to multiply before the fabric dries. Do not put odorous gym clothes in the dryer before treating — heat can set odour compounds deeper into synthetic fibres.
Prevention — wash synthetic athletic wear at 40°C immediately after use
The longer synthetic fibres remain damp after exercise, the more time bacteria have to establish biofilm colonies and generate volatile fatty acids. Wash or at minimum rinse gym clothes immediately after use. Do not leave damp gym clothes in a sealed bag for hours before washing. For synthetic athletic wear, inside-out washing exposes the inner surface (where most skin bacteria are deposited) directly to the detergent. Consider athletic detergents specifically formulated for synthetic fibres (Hex Performance, WIN Sports Detergent) which use surfactant systems optimised for hydrophobic synthetic fibres.
Odour Source and Treatment
Sour / rancid armpit or collar
Cause: Bacterial volatile fatty acids (butyric, valeric acids) from sweat metabolism
Vinegar pre-soak + enzyme detergent + 60°C (cotton) or 40°C (synthetics)
Musty / earthy all over
Cause: Mould or mildew — fungal metabolites (geosmin, 2-methylisoborneol)
See how-to-remove-mould-from-clothes guide — sodium percarbonate soak required
Stale / gymnasium synthetic gear
Cause: Bacterial biofilm in polyester/nylon fibres — harder to remove than in cotton
Vinegar soak (2–3 hrs) + baking soda in drum + 40°C enzyme wash + sun drying
Smoke / bonfire
Cause: Aromatic compounds (benzene, toluene, phenols) adsorbed onto fibre surface
Baking soda soak 4–8 hrs + 60°C wash (cotton) or 40°C (synthetics). May require repeat.
Chemical / new clothes smell
Cause: Formaldehyde or other finishing chemicals applied during manufacturing
Cold wash before first wear removes the majority. Some need 2–3 washes.
FAQ
Why do clothes still smell after washing?
The persistent smell is caused by bacterial biofilm — structured colonies of bacteria embedded in a protective polysaccharide matrix within the fabric fibres. Biofilm is significantly more resistant to normal washing than free-swimming bacteria. A 30°C wash removes surface bacteria but leaves established biofilm colonies largely intact, particularly in synthetic fibres (polyester, nylon) which provide an ideal hydrophobic surface for bacterial adhesion. The bacteria continue generating volatile fatty acids from any residual sweat compounds, and the smell returns. Acid pre-soak (vinegar) disrupts the biofilm matrix, and higher wash temperatures (60°C for cotton) kill the bacteria.
Does white vinegar remove smell from clothes?
Yes, and for a specific chemical reason. The acetic acid in white vinegar (typically 5% concentration) lowers the pH within the fabric and hydrolyses the polysaccharide matrix of bacterial biofilms, making the bacteria more vulnerable to subsequent washing. Vinegar also neutralises alkaline odour compounds directly. It is most effective as a pre-soak (30–120 minutes, not diluted) before the main wash, not added to the wash water itself. The vinegar smell fully dissipates during washing and drying — it does not transfer to the garment.
How do you get smell out of synthetic gym clothes?
Synthetic fibres (polyester, nylon) develop odour faster and more persistently than cotton because they are hydrophobic (bacteria prefer this surface) and cannot be washed at temperatures that kill bacteria (above 60°C). The most effective approach: soak in undiluted white vinegar for 2–3 hours, machine wash inside-out at 40°C with enzyme (biological) detergent and 3–4 tablespoons of baking soda in the drum, then air dry in sunlight. For very entrenched odour, repeat the cycle 2–3 times. Wash gym clothes immediately after use — do not leave them damp for hours, which allows biofilm to develop.
Is baking soda or vinegar better for removing smell from clothes?
They work by different mechanisms and are complementary — use them in separate steps, not together. Vinegar (acidic) is better for disrupting bacterial biofilm and dissolving the fatty acid compounds that cause body odour smell. Baking soda (alkaline) is better for adsorbing volatile molecules and neutralising acid odour compounds. Never mix them in the same wash water — the acid-base reaction neutralises both and leaves neither effective. The recommended sequence: vinegar pre-soak first, then baking soda in the machine wash.
Related guides
Got a stain as well?
Use the stain picker →