Bumps on the Back of Your Arms? Keratosis Pilaris Explained

The short answer

Those small, rough bumps are usually keratosis pilaris (KP). It happens when keratin, a protein in your skin, builds up and plugs hair follicles. It's very common, harmless and not caused by poor hygiene. There's no cure, but gentle care and regular moisturizing can make your skin look and feel smoother.

So many people have asked me about the little bumps on the backs of their arms. Usually they've been scrubbing at them for years, thinking they just needed to get cleaner. If that's you, here's the good news: it's not your fault, and scrubbing harder usually makes it worse.

This article is general information, not medical advice. If you're unsure what's going on with your skin, see a dermatologist.

What keratosis pilaris is

Keratin is a protein that helps protect your skin. With KP, extra keratin builds up and forms small plugs in the hair follicles. That's what creates the bumps. They can be skin-colored, red or a little darker than your skin, and they often feel like sandpaper.

KP usually shows up on the backs of the upper arms, and sometimes on the thighs, buttocks or cheeks.

Who gets it

It's very common, especially in kids, teens and young adults.
It often runs in families.
It tends to be worse in people with dry skin, and it's more common in people who have eczema.
Many people find it gets worse in winter and better in summer.

What helps

Wash gently. Use warm water and a gentle cleanser. Harsh soaps dry the skin out, and dry skin can make KP look worse.
Moisturize every day. Especially right after a shower, while your skin is still damp.
Look for smoothing ingredients. Dermatologists often suggest creams with ingredients like urea, lactic acid or salicylic acid, which help loosen the buildup over time.
Use a humidifier in dry months.
Be patient and consistent. It can take several weeks of daily care to see a difference, and if you stop, the bumps usually come back.

What to stop doing

Scrubbing hard. Rough scrubs and brushes can irritate the skin and make bumps redder.
Picking. It can lead to irritation, scarring or infection.
Long, hot showers. They dry your skin out.

When to see a dermatologist

See a dermatologist if the bumps are itchy, inflamed or spreading, if you're not sure it's KP, or if you've tried a gentle routine for a couple of months without improvement. A dermatologist can confirm what it is and suggest prescription options if you want them.

For most people, KP is just a quirk of their skin. Treat it gently, keep it moisturized, and don't let anyone tell you it means you're not clean.