Those small, rough bumps on the back of your arms are almost certainly keratosis pilaris, one of the most common skin conditions in the world. It’s completely harmless, though it can be annoying. The bumps form when a protein called keratin, which normally protects your skin, clumps together and plugs up your hair follicles. The result is a rough, sandpapery texture that people often describe as “chicken skin.”
What Causes the Bumps
Every hair on your body grows out of a tiny opening called a follicle. In keratosis pilaris, dead skin cells and keratin build up inside those follicles instead of shedding normally. Each plug creates a small, raised bump. The plugs tend to form on the backs of the upper arms, though they can also appear on thighs, buttocks, and cheeks.
Nobody knows exactly why keratin overproduces in some people and not others, but dry skin and friction make it worse. When your skin loses moisture, dead cells are more likely to stick together and clog follicles rather than sloughing off on their own.
Why You Specifically Have It
Genetics play a major role. An estimated 50 to 70 percent of people with keratosis pilaris have a genetic predisposition, and 30 to 50 percent have a close family member with the same bumps. It follows an autosomal dominant inheritance pattern, meaning if one of your parents has it, you have a significant chance of developing it too.
The condition also clusters with other dry skin issues. People with a condition called ichthyosis vulgaris, where skin doesn’t shed properly, have keratosis pilaris at a rate of about 74 percent. General dry skin of any kind tends to make the bumps more prominent. If you’ve dealt with eczema, asthma, or allergies, you may be more likely to notice these bumps as well, though the overlap isn’t as strong as once believed.
Age matters too. Keratosis pilaris most commonly starts either before age 2 or during the teenage years. If yours began in adolescence, there’s a good chance it will fade by your mid-20s. Many adults find it gradually disappears on its own, though for some it sticks around indefinitely.
Why It Gets Worse in Winter
If you’ve noticed the bumps are more obvious in colder months, that’s not a coincidence. Cold air holds less moisture, and indoor heating dries things out further. Since dry skin is the primary aggravator, winter creates ideal conditions for flare-ups. The bumps may flatten and become barely noticeable in summer, when humidity is higher and your skin stays naturally more hydrated.
Running a humidifier in your home during dry months can help counteract this cycle.
How to Smooth the Bumps
Keratosis pilaris doesn’t require treatment, but most people want smoother skin. The approach comes down to two things: keeping skin moisturized and gently exfoliating the keratin plugs.
Moisturizing
A thick, creamy moisturizer is the foundation. Look for one containing urea or lactic acid, both of which hydrate skin while also softening keratin. Urea at concentrations of 10 percent or lower works mainly as a moisturizer, while concentrations above 10 percent (like 20 percent urea creams) actively break down the excess keratin buildup.
Timing matters more than most people realize. Apply moisturizer within five minutes of getting out of the shower while your skin is still damp, which locks in significantly more hydration. Reapply at least two to three times a day on the affected areas, massaging gently into the bumps.
Exfoliating
To actually reduce the bumpy texture, you need to clear the plugged follicles. A loofah or washcloth used gently in the shower can help, but over-the-counter products with specific ingredients do more. Look for:
- Lactic acid or glycolic acid: dissolve the bonds holding dead skin cells together
- Salicylic acid: penetrates into the follicle to clear plugs from the inside
- Urea at 20 percent: both hydrates and exfoliates in one step
Start with a single product and use it consistently for several weeks before judging results. If your skin becomes dry, red, or irritated, scale back to every other day. These ingredients work gradually, not overnight.
Prescription Options
If over-the-counter products aren’t enough, a dermatologist can prescribe stronger options. Retinoids speed up skin cell turnover, preventing new plugs from forming. A mild corticosteroid cream can reduce redness and soften stubborn bumps. For persistent cases that don’t respond to creams, certain laser treatments can reduce both the redness and texture.
What Not to Do
Picking or squeezing the bumps is tempting but counterproductive. It can cause inflammation, scarring, and even infection. Scrubbing aggressively with harsh exfoliants can also irritate the skin and make bumps redder and more noticeable. Hot showers feel good but strip your skin of its natural oils, worsening the dryness that drives keratosis pilaris in the first place. Lukewarm water is a better choice.
It’s also worth knowing that keratosis pilaris can cause real emotional frustration. Studies have found that people with the condition report embarrassment, decreased self-confidence, and avoiding situations where their skin is visible. If that sounds familiar, know that it’s an incredibly common condition and that consistent treatment can make a visible difference within a few weeks.