Roughly half the population will suffer from dandruff at some point in their lives, according to the NHS.
While it's a very common condition - it can still cause embarrassment.
But now Francesca Fusco, a medical and cosmetic dermatologist from New York, has explained where many a dandruff-sufferer has been going wrong.
If you use a special anti-dandruff shampoo you must not follow that up with a regular old conditioner. You might think that it would enrich the hair and make it look extra healthy - and surely the shampoo has done its job - but you'd be wrong.
Unilever has done studies on this, and they found that when people use dandruff shampoo, specifically ones with zinc pyrithione, and they use a beauty conditioner afterwards they can rinse away up to 50 per cent of the flake-fighting effects of the medicated shampoo.