Sweat marks under the arms

Sep 12, 2026

Short answer: Yellow sweat stains come from a reaction between sweat and deodorant. Rinse the area in cold water after wearing and wash at 40 degrees before the stain sets. Avoid warm drying while a stain is still visible.

Why the stain turns yellow

Salts in sweat react with aluminium salts in deodorant and form a yellowish deposit in the fabric. At first you hardly see it, but it builds up each time the garment is worn and washed without rinsing. It stays put if it dries in, for example in a bamboo tank top for men.

Rinse before washing

Hold the underarm under cold water for a minute before the top goes in the laundry basket. That removes most of the sweat and deodorant before it sets. Squeeze the fabric gently under the water, but do not rub. A small habit that makes a big difference, also on bamboo sweatshirts for women.

Avoid warm drying

A tumble dryer or radiator sets the yellow colour, making it very hard to remove. Hang clothes to dry at room temperature instead. Air drying leaves the option to treat the stain again if it did not come out in the first wash. The same goes for the soft bamboo sweatshirts for women.

Soak older stains

If the stain is already yellow, soaking can help. Leave the area in lukewarm water with a little detergent for a couple of hours. Work the fabric gently with your fingers now and then, and wash as usual afterwards. You may need to repeat it a few times before the stain is gone or much fainter.

Let deodorant dry

Put your clothes on only once the deodorant is completely dry. Wet deodorant settles into fabric more easily and leads to white marks and yellow stains over time. Wait a few minutes after applying, and use no more than you need. Less ends up in the fabric, and stains build up more slowly.

Wash often and at the right temperature

Clothes worn close to the body should be washed after every wear or two. The longer sweat and deodorant stay in the fabric, the more they set. A normal wash at 40 degrees is usually enough if the underarms were rinsed first. Always follow the care label on the garment.

Turn clothes inside out

Turn tops inside out before they go in the machine. That way water and detergent reach the side that was against the skin, where sweat and deodorant sit. The outside also gets less wear in the wash. It is an easy habit that suits almost any garment.

White shows it most

Sweat stains form on all colours, but on white and light fabric they quickly become visible. On dark clothes you more often see white deodorant marks. If you wear a lot of white and light clothing, it is worth rinsing after wear and keeping clothes away from heat until they are clean.

Frequently asked questions

Can yellow underarms be saved

Often yes, if they have not been exposed to heat. Soak the area in lukewarm water with detergent for a couple of hours, then wash as usual. Repeat if needed.

Does switching deodorant help

For many people, yes. Products without aluminium salts leave fewer yellow deposits, since that reaction is what creates the colour. Other marks can still appear, so keep rinsing after wear.