Keratosis pilaris: those little bumps on your arms

Run your hand over the back of your upper arm. If it feels like fine sandpaper, with tiny bumps that look a bit like permanent goosebumps, you’re probably looking at keratosis pilaris. It’s one of the most common skin conditions there is, it’s completely harmless, and it’s remarkably stubborn. Here’s what’s going on under those bumps and what genuinely helps.

What keratosis pilaris is

Keratosis pilaris (often shortened to KP) happens when keratin, the tough protein that makes up the outer layer of your skin, your hair and your nails, builds up inside hair follicles instead of shedding normally. Each little plug blocks a follicle and pushes up a small bump.

The bumps are usually skin-coloured, but they can look red or, on deeper skin tones, brown. Sometimes there’s a coiled hair trapped underneath. They cluster on the backs of the upper arms and the fronts of the thighs, and can also show up on the buttocks, trunk and, in children, the cheeks. They’re occasionally itchy, mostly just rough. They aren’t pimples, even though they’re often mistaken for acne: there’s no infection and nothing to squeeze out.

How common is it?

Very. DermNet puts it at 50 to 70 percent of teenagers and about 40 percent of adults. If you have it, you’re in the majority, not the minority.

It typically begins in childhood, is most noticeable in the teenage years, and often fades in adult life. It runs in families in a dominant pattern, meaning one parent with KP is enough to pass it on. There’s no cure, but it’s not a disease so much as a skin type.

The link to dry skin and eczema

KP keeps company with dry skin. DermNet notes it’s associated with atopic eczema (the common, itchy form of eczema where the skin barrier leaks), with ichthyosis vulgaris (an inherited condition of very dry, scaly skin), and with mutations in filaggrin, a protein that helps skin cells form a proper barrier. If your skin already struggles to hold moisture, keratin plugs seem to form more readily.

That also explains the seasons. Bumps tend to be worst in winter, when the air holds less moisture, and many people find they fade in summer. In Canada, where heated indoor air can be desert-dry from November to April, that pattern is especially familiar. Dryness doesn’t cause KP, but it makes it rougher and more visible.

What actually helps

The strategy has two parts: loosen the plugs and keep the skin moisturized. Both the American Academy of Dermatology and DermNet describe the same toolbox.

Keratolytics: ingredients that loosen keratin

A keratolytic is an ingredient that softens or loosens keratin so plugs break down and shed. The ones used for KP are:

• Urea. A natural component of skin that both holds water and, at higher strengths, softens keratin. Common in body creams for rough skin.
• Lactic acid. An alpha hydroxy acid that loosens dead surface cells and also acts as a humectant, drawing water into the skin. In a 2023 survey of dermatologists, it was the most common first choice, used by about 44 percent.
• Salicylic acid. A beta hydroxy acid that dissolves in oil and gets into the follicle. Second choice in that survey, at about 21 percent.
• Glycolic acid and topical retinoids (vitamin A relatives, some by prescription) are also used.

How well do they work? Honestly, moderately. The best comparison is a 2015 randomized trial in which people applied either 10 percent lactic acid or 5 percent salicylic acid cream twice daily for three months. Bumps decreased by 66 percent with lactic acid and 52 percent with salicylic acid, both statistically significant, with skin hydration improving and side effects limited to mild local irritation. A 2025 review of all the keratolytic studies concluded that lactic acid, salicylic acid and urea all show benefit, but that the evidence rests on small studies with short follow-up, inconsistent measurements and little blinding. So: reasonable first options, no clear winner.

Moisturizing

This is the unglamorous half that does much of the work. The AAD’s advice:

• Apply a thick cream or ointment, ideally one containing urea or lactic acid, to damp skin within five minutes of bathing, and again whenever skin feels dry.
• Keep showers and baths short (20 minutes or less), once a day, in warm rather than hot water.
• Use a mild cleanser instead of bar soap.
• Run a humidifier when indoor air is dry, which in a Canadian winter is most of the time.

Gentle exfoliation, not scrubbing

The AAD suggests gently exfoliating with a soft washcloth or loofah, and explicitly warns against scrubbing, which irritates skin and makes KP redder. If a keratolytic product leaves your skin dry or irritated, pause it and just moisturize until things calm down.

What doesn’t help

• Picking and squeezing. There’s no pus to release. Picking leaves marks and can scar, and DermNet notes that any scarring or hair loss may be permanent.
• Harsh scrubs and hot showers. Both strip the barrier and make the roughness worse.
• Waiting for a cure. There isn’t one. A 2023 survey found more than 60 percent of dermatologists saw bumps return within three months of stopping treatment. The AAD’s framing is a maintenance plan: treat daily until skin is smoother, then a few times a week to keep it that way.
• Expecting overnight results. The AAD suggests giving a routine four to six weeks before judging it.

For persistent redness or stubborn cases, laser and light treatments exist; those are clinic decisions, not shelf ones. And if the bumps are painful, spreading fast, or you’re not sure it’s KP, see your doctor or pharmacist. A few other conditions can look similar.

You can browse the panel’s reviewed exfoliators or moisturizers.

The takeaway: keratosis pilaris is harmless, extremely common, genetic and tied to dry skin, which is why Canadian winters bring it out. It won’t be cured, but it will be managed: a keratolytic like urea, lactic acid or salicylic acid to loosen the plugs, a thick moisturizer on damp skin every day, no scrubbing and no picking. Give it six weeks, keep it up, and expect the bumps to fade with the seasons and, often, with age.