WHAT IS KERATOSIS PILARIS?
Keratosis pilaris is a build-up of keratin (the protein that makes up the outer layer of your skin) inside the hair follicle. Instead of the dead skin cells shedding the way they're meant to, they form a tiny plug that traps the hair beneath it. That's the bump. Multiply it by hundreds and you've got the rough, sandpapery feel that gives the condition its nickname.
The bumps tend to appear on the backs of the upper arms, the fronts of the thighs, occasionally on the buttocks, and sometimes on the cheeks (the facial version is often confused with acne, but it isn't). Some people get a redness around the bumps too, which is the inflammation associated with the trapped follicle. That's the strawberry skin variant.
It's not contagious. It's not a sign of poor hygiene. It's not because you've done something wrong with your skincare. It runs in families and it tends to be worse in people with dry skin, eczema, or asthma.