Question: what causes bumps on the back of your upper arms?
Answer: Keratosis pilaris (ker-uh-TOE-sis pih-LAIR-is) is a common, harmless skin condition that causes dry, rough patches and tiny bumps, usually on the upper arms, thighs, cheeks or buttocks. The bumps generally don't hurt or itch. Keratosis pilaris is often considered a variant of normal skin.