Keratosis pilaris (pronounced ker-uh-toe-sis pih-lair-is) is a harmless, non-contagious skin disorder. This is also known as keratosis follicularis, lichen pilaris and follicular keratosis. Keratin is a substance found in skin, hair and nails, so ‘keratosis' means there is too much of this protein, which makes up the horny outer layer of the skin, while 'pilaris' comes from the Latin for hair (pilus).
An overproduction of keratin blocks the hair follicles and small bumps to form. This causes the outermost layers of skin to thicken, especially on the upper arms and thighs but also on the buttocks and on the face. Small pimples develop and the skin feels rough and uneven − hence why keratosis pilaris is often referred to as ‘chicken skin’. Keratosis pilaris commonly appears on the face, arms and legs.