How many people have keratosis pilaris?

How common is KP at different ages?

The full name is keratosis pilaris, though KP saves everyone a small amount of paperwork. The estimates differ by age, so one percentage cannot describe children, teenagers and adults equally well.23

The teenage estimate is a range, not a single settled figure: estimates include 50% to 70% as well as the broader 50% to 80%. Adult estimates are more consistently around 40%. KP is also underreported, so the actual proportion affected could be higher. Many people have no symptoms beyond the bumps, and some do not realise they have KP.124

These percentages describe how common KP is, not an exact worldwide headcount, because a percentage is not a roll call for the entire planet. They are best read as broad estimates rather than precise odds for a particular person. Some estimates describe people who develop the bumps at some point in their lives, rather than everyone who has visible bumps today.5

Why do fewer adults have KP?

KP usually starts early in life, often before age 2 or during the teenage years. Childhood bumps can clear by late childhood or adolescence, then flare again around puberty. KP that starts during the teenage years often clears by the mid twenties, but it can continue into adulthood. There is no birthday at which the bumps must disappear.3

Why do I have keratosis pilaris?

KP develops when keratin, a protein in the skin, builds up and plugs hair follicles, the openings where hairs grow. Instead of shedding normally, the material collects in the follicle and forms a rough bump. The process behind the bumps is understood better than the reason some people develop them and others do not.45

KP runs in families, and genes play a role. Changes in FLG, a gene involved in the skin's protective barrier, are linked with KP and dry, scaly skin. Having a close blood relative with KP increases your likelihood of developing it. Dry skin, eczema, asthma and hay fever are also associated with a higher likelihood. People of all ages and races can have KP.346

What do the common bumps look like?

KP causes tiny bumps that feel rough and dry. They can match your skin colour or look white, red, pinkish purple or brownish black. Children commonly have bumps on the upper arms, fronts of the thighs and cheeks. In teenagers and adults, the upper arms, fronts of the thighs and buttocks are common sites. Some people have only a few bumps; others have much wider patches.7

Bumps can become more noticeable in winter or a dry climate, and they sometimes itch. A seasonal change in how obvious KP looks does not necessarily mean it has newly developed. KP can fluctuate over time rather than remain equally noticeable all year.17

Does KP need treatment?

KP is harmless, is not contagious and usually does not need treatment. If the texture bothers you, moisturising and gentle skin care can soften the bumps. Apply moisturiser after showering while the skin is still damp, and avoid hard scrubbing, which can worsen irritation. There is no cure, although KP often improves with age. If the bumps hurt, the symptoms concern you or you are unsure what they are, a doctor can examine the skin.45