What is Dandruff?


It’s itchy.  It’s flaky. It’s white all over your black clothes.  You’re showering and washing your hair, but you worry that others are judging your hygiene based on the desert sandstorm that has accumulated on your shoulders.  Trust me, I know; I’ve been there. The most common cause of dandruff is a skin condition called seborrheic dermatitis.  Seborrheic dermatitis is a hypersensitivity to yeast that are part of your normal skin flora (translation: on everyone’s skin).  Some people are prone to developing a reaction to this yeast (malassazia furfur, formerly known as pityrosporum ovale).  It’s pretty random who gets it and is thought to be due to a combination of both genetic and environmental factors.  You may just notice a little flakiness coming from your scalp or it can be a bit more severe, causing the skin to turn red with overlying greasiness and scaliness.  Seborrheic dermatitis may even affect other parts of your skin: some people get a rash around their eyebrows, nose folds, behind the ears, chest, and even the groin.  

The second most common cause of dandruff is psoriasis.  Psoriasis is a chronic, inflammatory skin disorder that can affect almost anywhere on your skin; classically, it affects the scalp, lower back, arms, and legs.  It can even affect your nails and joints. There are other less common causes of scalp flaking and itching that would be best for a dermatologist or other physician to evaluate.  

Ok. I have it. Now what?

So, you realize it’s getting out of control.  It’s time to set an appointment with your dermatologist, who can help clarify the diagnosis, screen for related conditions, and send a script for prescription strength products (including medicated shampoos and topical corticosteroids).  Unfortunately, they don’t have an opening for weeks and you’re miserable with itch.  What can you do in the meantime? The good news is that there are tons of great over the counter products that can help you.  The other good news is that you don’t have to worry about distinguishing seborrheic dermatitis from psoriasis — the same shampoos tend to help both disorders; you can leave that tough job up to us dermatologists.  See related blog posts for tips on choosing and using a medicated shampoo.


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