The human body perspires after exposure to high temperatures, when muscles create heat, in response to emotional stimuli and as a response to certain foods. Thermoregulation is the major trigger for sweating. Perspiration is primarily a function of the body’s need to cool itself. When ambient temperatures rise above the body’s resting temperature, generally 98.6 degrees Fahrenheit, temperature receptors on the skin alert the brain to begin the sweating process. The body accomplishes this task by stimulating sweat production in either the eccrine sweat glands, the apocrine sweat glands, or both.
Chromhidrosis
Chromhidrosis is a rare condition that a causes perspiration to be colored. The apocrine sweat glands are primarily located in the underarms and in the anogenital region. These glands do not become functional until a person reaches puberty. The fluid produced by these glands is thicker and milkier than the sweat produced by the eccrine sweat glands. Apocrine sweat contains proteins and fatty acids.
In rare cases, a yellow-brown, finely granular pigment, called lipofuscin, mixes with sweat and sweat appears colored. Associated with aging, these pigments can be found in the liver, heart muscles, nerve cells and kidney cells. International Anti-Aging Systems explains that lipofuscin results from free-radical damage to fats and proteins.
Apocrine chromhidrosis cannot be so easily treated. This is because the condition is so rare and not fully understood. Some promising treatments include the topical application of capsaicin, an ingredient in peppers, or treatment with botulinum, the neurotoxin used in Botox and Myobloc.
Pseudochromhidrosis
Pseudochromhidrosis is a variation of chromhidrosis, according to Annals of Internal Medicine. Pseudochromhidrosis occurs when colorless sweat reaches the skin and mixes with agents such as bacterial byproducts, dyes, chemicals and pigments. If the colorant is yellow, sweat will appear yellow. Treatment involves identifying the colorant and avoiding it in the future. Pseudochromhidrosis caused by bacteria can be treated with antibiotics, according to Dermatology Review.
Bacterial Sweat Stains
In most cases, “yellow sweat” is not really yellow. Rather, sweat is clear when it leaves the body. When apocrine sweat reaches the skin’s surface, bacteria that live on the skin metabolize the fats and oils in the sweat and produce the odor associated with sweat and the colored liquid that transfers to clothing and causes “sweat stains.”
Family and Consumer Sciences reports in its newsletter, “Clothesline,” that the age of the stain and the heat used in clothes washing can oxidize the stain and turn it yellow.
When the cause is bacterial, a physician or dermatologist might simply recommend trying a different antiperspirant. The International Hyperhidrosis Society recommends using a semi-soft antiperspirant, applying it to dry skin and allowing it to dry before dressing. Antiperspirants plug sweat ducts.
