Q. What causes dandruff, and is it a health problem?
A. Cells on our scalps are constantly dying and falling off, but for people with dandruff this process kicks into high gear. Scaly flakes of skin form on the scalp and shed rapidly, and they become visible in the hair and on the shoulders. The scalp can also become itchy, irritated, and red. Dr. Gary Goldenberg, a dermatologist at Mount Sinai School of Medicine, says that while we think of dandruff as affecting only the scalp, it’s considered a form of seborrheic dermatitis, an inflammatory condition that causes redness, flakiness, and itching on the scalp, face, chest, and groin.
Dandruff is different from dry skin; in fact, it’s more often associated with oily skin and hair. Goldenberg says that some people seem to have a genetic predisposition to these pesky flakes. It’s also thought to stem from an over-reaction of the immune system to fungi called Malassezia, which feed on oils in the hair and scalp. But the exact chain of events that leads to dandruff is unclear. Dandruff shampoos work by tackling different aspects of the process, some with antifungal agents and others with substances that de-flake the scalp or slow the rate of shedding.
Dandruff is a generally harmless but embarrassing condition that can often be controlled but is difficult to cure. It’s not a sign of an overall health abnormality, Goldenberg says. “However, in patients with very severe dandruff, it may be a sign of immune deficiency.”