Dandruff is caused by dry scalp
“Dandruff is caused by a type of yeast that tends to overgrow in an oily environment,” says Dr. Piliang. “Dandruff is your body’s reaction to the yeast.” That’s a problem if you cut down on washing in an attempt to diminish dandruff: use an anti-dandruff shampoo, but don’t scale back your suds sessions.