What Causes Underarm Rash?

An underarm rash can be uncomfortable because of the heat and moisture that accumulates in the armpit. Constant rubbing and the inability to avoid contact only exacerbate the situation. Some cases of underarm rash are avoidable, while others may occur because of allergies or medicinal reactions.

Contact

Contact dermatitis occurs when the skin is exposed to an allergen, such as a new soap or deodorant. The Mayo Clinic describes the symptoms of contact dermatitis as the appearance of red bumps that are inflamed and itchy. The condition is usually apparent after first contact with the irritant. If the blotches and itching are delayed, the dermatitis is most likely the result of an allergic reaction to a material like nickel, a common ingredient in jewelry, buttons and zippers. A physician usually can diagnose the bumps by their appearance and a history of new products that may have been used. After identifying the cause of the rash, the main treatment is prevention and avoiding that product. Topical and oral medications can be used to mediate the symptoms while the condition heals. Contact dermatitis typically goes away within a couple weeks, although it can take months for all signs to disappear.

Scarlet Fever

One symptom of scarlet fever is a red rash on the underarm and in the groin creases. Those who have contracted the disease begin to see the rash within one or two days of being infected. The first signs are fever and sore throat, followed by a rash that begins on the chest and neck that spreads to the underarms. The National Institutes of Health reports that scarlet fever is caused by the same bacteria that causes strep throat and is easily treatable with antibiotics. A throat culture is the best way to test for the illness. While antibiotics will clear up the fever and infection, the rash may take up to 2 or 3 weeks to dissipate.

Shaving

Shaving can cause ingrown hairs and razor bumps that leave the underarm areas bumpy and itchy. Curly hairs that curve around and grow back into the skin create the rash. Ingrown hairs result from cutting the hair too close to the skin. According to doctors at the Redding Dermatology Medical Group, proper shaving techniques result in hairs being cut off at the skin surface with minimal irritation and friction. Treatment of recurring shaving related underarm rashes is usually done by changing shaving equipment and methods. Hair cuts more smoothly after it has been wet for at least 5 minutes. People who are prone to razor rashes should shave at the end of a shower or bath. To avoid rashes, shave in one smooth swipe, rather than repeatedly going over the same area. Downward strokes that follow the grain of the hair growth also minimize shaving rashes. While many believe they get a closer cut by stretching the skin, taut skin actually provides a breeding ground for rashes to develop. Finally, a good shaving get that makes the hairs rise to the razor can help prevent rashes and ingrown hair.