Q: I have a bunch of small, rough bumps on my arms and legs. What are they, and how can I get rid of them?

Maybe they look like goose bumps — or the skin of a plucked chicken. Perhaps they’re raised and feel a little bit like sandpaper.

These may be the signs of keratosis pilaris, a common skin condition that can cause tiny, painless bumps to appear on the upper arms, thighs and buttocks, said Dr. Amy Freeman, a dermatologist in Millburn, N.J.

The bumps are typically flesh-colored, but they might look red or pink on lighter skin tones and brown or black on darker skin tones.

While their appearance can be “distressing,” Dr. Freeman said, keratosis pilaris bumps are harmless and often go away on their own. However, some people can deal with flare-ups for their entire lives.

What causes keratosis pilaris?

Keratosis pilaris happens when keratin — a protein involved in forming hair, skin and nails — builds up and, along with dead skin cells, clogs hair follicles, Dr. Freeman said. These blockages are what cause those small bumps.

An estimated 40 percent of adults and 50 to 80 percent of teenagers have keratosis pilaris. But dermatologists aren’t sure exactly why some people develop it.

One theory is that the condition is caused by a genetic mutation that interferes with the skin’s ability to moisturize itself naturally, said Dr. Shari Lipner, a dermatologist at Weill Cornell Medicine in New York City. The mutation may make you more prone to dry skin, which makes keratosis pilaris worse.

People who have eczema, diabetes or close blood relatives with keratosis pilaris are also more prone to the condition, Dr. Lipner said. The same is true for people with asthma, allergies or excess body weight, according to the American Academy of Dermatology, or A.A.D.

Because dry skin worsens keratosis pilaris, you may have more flare-ups during the winter or if you live in a dry climate, said Dr. Leslie Baumann, a dermatologist in Miami.

Can you treat keratosis pilaris at home?

Preventing dry skin is one of the best ways to reduce flare-ups and generally improve the appearance of keratosis pilaris, Dr. Baumann said.

Products that contain emollients (moisturizers) and keratolytic agents (a class of medications like salicylic acid, lactic acid and urea that remove dead skin cells and soften the keratin that clogs pores) are most effective, Dr. Freeman said.

A convenient option is to choose an over-the-counter moisturizing lotion that contains a keratolytic agent, Dr. Lipner said. The A.A.D. also recommends products with other keratolytics like glycolic acid and retinol.

These ingredients help smooth out the bumps and reduce redness, Dr. Freeman said.

And they’ll be most effective if you apply them right after showering when your skin is still damp, Dr. Lipner added. Doing so helps seal some of the moisture into your skin.

Dr. Lipner suggested avoiding anything that might irritate your skin, such as using an abrasive body scrub or scratching or picking at the bumps. However, the A.A.D. says you can gently use a loofah or washcloth to slough off dead skin cells. It’s also best to avoid products with fragrances and oils, which can irritate the skin and clog pores even more, Dr. Lipner said.

During a flare-up, Dr. Freeman said, you should use a moisturizer with a keratolytic agent a few times a day for a couple of months. Once the condition improves, you can taper down to a few times a week.

But you should still moisturize every day, she said; you just don’t need a keratolytic product once the flare-up is under control.

Can you prevent keratosis pilaris?

Keratosis pilaris isn’t preventable, but some people who have it as children will find that it goes away when they are older. Others deal with it for their entire lives.

“But there may be periods of your life where it’s so quiet that the bumps are so small and not visible that it’s almost not there,” Dr. Lipner said.

When should I see a dermatologist?

If your skin is still bumpy and rough after using at-home products for a few months and you’re bothered by how it looks, Dr. Lipner suggested seeing a dermatologist.

“There are people with very severe keratosis pilaris, and moisturization may not be enough,” she said. They may also have flare-ups that are extra red and dry and perhaps even itchy. In those cases, Dr. Lipner said, doctors can prescribe a topical retinoid or suggest laser therapy.

But your symptoms might also be from something else. Eczema and psoriasis can resemble keratosis pilaris, Dr. Lipner said. These conditions can cause itchiness, inflammation, cracks in the skin or infections, and need their own specific treatments.