Unsightly yellow sweat stains are a common and vexing problem. Perspiring primarily functions to cool your body as sweat evaporates from your skin surface. Your body perspires in response to high environmental temperature, exercise, certain foods, and emotional or sexual arousal. Sweat is normally colorless but might turn a yellowish color due to interaction with bacteria or chemicals on the skin surface or your clothing. A rare disorder called chromhidrosis causes colored sweat, which can be yellow, green, blue or another hue.
When you notice yellow sweat stains on a shirt, most often in the armpit area, you might presume it is due to yellow sweat. But this is rarely the case. Yellow sweat stains usually occur due to a chemical reaction between colorless sweat and chemicals from your deodorant or antiperspirant -- especially aluminum. Breakdown of fats and proteins in sweat by bacteria and fungi normally present on your skin that transfer to your clothes can also contribute to the formation of yellow sweat stains. Steps you can take to reduce the occurrence of those dreaded yellow armpit stains include:
-- laundering your clothing as soon as possible after wear
-- not applying excess antiperspirant or deodorant
-- allowing your antiperspirant or deodorant to dry before putting on your shirt
-- switching to an aluminum-free deodorant
Chromhidrosis is a rare condition that a causes a person to produce colored perspiration. This condition usually affects only the apocrine sweat glands, which are limited to the armpits, groin, nipple area of the breasts, eyelids and the area around the nose. These sweat glands do not become functional until puberty. With chromhidrosis, the sweat produced by the apocrine glands contains a yellowish-brown pigment called lipofuscin. People with this condition most commonly secrete yellow sweat, but it can be green, blue or black due to additional chemical modification of the lipofuscin. The cause of chromhidrosis remains unknown.
Eccrine sweat glands occur on virtually all areas of the skin and become fully functional by 2 months of age. These sweat glands are much more numerous than aprocrine glands and produce most of the perspiration secreted by your body. Eccrine chromhidrosis is even more rare than the apocrine form of the disorder. This is usually due to the accumulation of dyes or other pigmented chemicals in the body. Yellow eccrine chromhidrosis might occur with severe liver disease resulting in very high levels of the yellow-colored chemical bilirubin in the body. The medication phenazopyridine (Pyridium) might also cause yellow or orange discoloration of the urine, tears and sweat.
Pseudochromhidrosis, also known as extrinsic chromhidrosis, refers to discoloration of perspiration after its secretion from the sweat glands. This condition occurs when colorless sweat reaches the skin and mixes with agents such as bacterial byproducts, fabric dyes, chemicals and pigments. If the colorant is yellow, the sweat will appear yellow. Overgrowth of certain bacteria on the skin can cause this condition, although the discoloration of sweat is not usually yellow.
Yellow perspiration stains on your shirts probably doesn't indicate you're secreting yellow sweat or signal a medical problem. However, if you notice yellow discoloration of your skin or the whites of your eyes, see your doctor as soon as possible. Similarly, see your doctor if you observe yellowish liquid sweat or fine yellow debris in the skin folds of your armpits, palms, soles or elsewhere.
Reviewed and revised by: Tina M. St. John, M.D.