What is keratosis pilaris?

Keratosis pilaris is a harmless skin condition characterized by tiny bumps on the back of the upper arms, the front of the thighs, the buttocks, and sometimes the cheeks of the face. The bumps are about the size of pinheads and evenly spaced. They are usually skin-colored or whitish-gray and may be individually ringed in red. The affected area may feel rough, like coarse sandpaper or "gooseflesh." The condition affects as many as 40% of adults — women more often than men. It usually begins in childhood and worsens during puberty, but — thankfully — it often improves in adulthood.

Keratosis pilaris is caused by an excessive buildup of keratin, a protein found in skin, hair, and nails. The keratin forms hard plugs in the openings of sebaceous glands adjacent to hair follicles, blocking the follicle openings and producing the characteristic bumps. Experts don't know why this buildup occurs in some people but not others. The condition tends to run in families, and genetic factors are probably involved. It's also more common in people with either of two other skin conditions — eczema and ichthyosis vulgaris — both of which are characterized by very dry skin. Keratosis pilaris tends to get worse in dry, cold weather and improve when warmth and humidity increase.

At times, patches of affected skin may become red, inflamed, or itchy, but in general keratosis pilaris is not a sign of illness. The problem is mainly cosmetic. Although there's no cure, there are several things you can do to improve the appearance of your skin, mainly by softening the keratin deposits. You have to practice these techniques continuously until the condition goes away:

• Keep your skin moist and well hydrated. Use a mild, fragrance-free soap and a skin moisturizing cream or ointment, which is better at moisturizing than a lotion. Creams containing urea (a rehydrating agent) soften dry skin.

• Exfoliate your skin with an over-the-counter preparation containing alpha-hydroxy acids, such as glycolic acid or lactic acid.

• Avoid scrubbing the bumps with a pumice stone or harsh brush; it can irritate the skin and aggravate the condition.

• Avoid scratching or picking at the bumps; it can cause bacterial infection or scarring.

If these strategies don't work, make an appointment with your primary clinician or dermatologist. He or she may recommend or prescribe additional treatment, such as a stronger topical alpha- or beta-hydroxy acid or a retinoid such as tretinoin (Retin-A) or tazarotene (Tazorac).