What causes yellow sweat spots?

Unpleasant yellow sweat stains are a common and annoying problem. Perspiration works primarily to cool your body as sweat evaporates from the surface of your skin. Your body perspires in response to high ambient temperatures, exercise, certain foods, and emotional or sexual arousal. Sweat is usually colorless, but can turn yellowish due to interaction with bacteria or chemicals on the skin surface or on clothing. A rare disorder called chromhidrosis causes colored sweat, which can be yellow, green, blue, or another shade.

Why do yellow spots appear on the fabric?

When you notice yellow sweat stains on a shirt, most often in the armpit area, you can assume it is due to yellow sweat. But this is rarely the case. Yellow sweat stains generally occur due to a chemical reaction between colorless sweat and the chemicals in your deodorant or antiperspirant , especially aluminum. The breakdown of fats and proteins in sweat by bacteria and fungi normally present on your skin that are transferred to your clothing can also contribute to the formation of yellow sweat spots. The steps you can take to reduce the appearance of those dreaded yellow underarm spots are:

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  • Wash your clothes as soon as possible after use
  • Do not apply antiperspirant or deodorant in excess
  • Allow your antiperspirant or deodorant to dry before putting on your clothes
  • Switch to an aluminum-free deodorant

What is aprocrine chromhidrosis?

Chromhidrosis is a rare condition that causes a person to produce perspiration of color. This condition usually affects only the apocrine sweat glands, which are limited to the armpits, groin, nipple area of the breasts, the 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 usually secrete a yellow sweat, but it can be green, blue, or black due to the additional chemical modification of lipofuscin. The cause of chromhidrosis remains unknown.

What is eccrine chromhidrosis?

Eccrine sweat glands occur in virtually all areas of the skin and become fully functional at 2 months of age. These sweat glands are much more numerous than the aprocrine glands and produce most of the perspiration secreted by your body. Eccrine chromhidrosis is even rarer 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 can occur with severe liver disease that results in very high levels of the yellow chemical bilirubin in the body. The medicine phenazopyridine can also cause yellow or orange discoloration of urine, tears, and sweat.

What about pseudochromhidrosis?

Pseudochromhidrosis, also known as extrinsic chromhidrosis, refers to discoloration of perspiration after it is secreted by the sweat glands. This condition occurs when colorless sweat reaches the skin and mixes with agents such as bacterial by-products, fabric dyes, chemicals, and pigments. If the dye 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 do not indicate that you are secreting yellow sweat or indicate 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 notice yellowish liquid sweat or fine yellow residue in the skin folds of your armpits, palms, soles of the feet, or elsewhere.