What it is
Dandruff is a common, non-contagious scalp condition that causes the scalp to shed visible flakes. It is considered a mild form of seborrheic dermatitis.
Common signs
white or yellowish flakes on the scalp, hair or shoulders · an itchy scalp · flakes that come back when you stop treating them.
What can make it worse
oil on the scalp, infrequent shampooing, cold dry weather and stress.
What helps
Shampoos with OTC dandruff ingredients such as salicylic acid, zinc pyrithione, selenium sulfide, sulfur, coal tar or ketoconazole. Massage the shampoo into the scalp and follow the product directions — some need to stay on for several minutes before rinsing. Salicylic acid works as a keratolytic: it helps loosen and lift flakes so they rinse away.
When to see a dermatologist
if dandruff doesn't improve after regular use of a dandruff shampoo, if it is severe, or if your scalp is very red, swollen or painful.
Last updated: October 2026
Sources: AAD — How to treat dandruff · MedlinePlus — Dandruff, cradle cap and other scalp conditions · 21 CFR 358 Subpart H