Q: I am getting recurring "boils" under my arms that I never had before. I've gotten about 14 over the last 6 months. I am just getting over having four large ones at one time under one arm. What causes this and how can it be treated?

A: "Boils" under the arms can be very painful. They may occur for several reasons. Possible causes are bacterial infection of the skin, irritation and infection of the hair follicles, and a condition called "hidradenitis suppurativa."

Bacterial infections can lead to painful, red, draining "boils." Irritation of the hair follicles can be caused by using perfumed deodorants or shaving. This creates an entry for secondary infection. Certain strains of staphylococcus can be especially problematic. They need to be treated with oral (by mouth) antibiotics.

Painful draining cysts or boils can also be caused by "hidradenitis suppurativa." This recurring condition involves certain sweat glands found primarily under the arms and in the groin. It is more common in women and it's worse in people who are overweight. It usually occurs between the ages of 20 and 40. (Starting after menopause is rare.) Flare-ups are treated with oral antibiotics.

If you have painful boils under your arms, see your doctor.

Rebecca Campen, M.D., J.D., is an Assistant Professor of Dermatology at Harvard Medical School and former Deputy Director of the Harvard/Massachusetts General Hospital Cutaneous Biology Research Center (CBRC). She currently serves as Senior Advisor to the CBRC and divides her time between clinical practice of dermatology at the Massachusetts General Hospital and private practice in Savannah, Georgia. Dr. Campen is the author of two books for medical students and residents, Going Into Medical Practice and Blueprints in Dermatology.