If you’ve ever scratched your head only to see little white flakes cascading down like snow, then there’s a pretty good chance you’ve Googled the cause. While the search engine likely helped you come to the conclusion of dandruff right from the top, it might not have made the causes—or what dandruff really is—immediately clear. That’s why we’re here. With the help of two board-certified dermatologists, ahead, you’ll discover the most common causes of dandruff, as well as what dandruff actually is to begin with.


First Things First: What Is Dandruff?


We all know it has to do with flakes, but board-certified dermatologist Adeline Kikam, DO, FAAD, the founder of @brownskinderm (a social media account dedicated to inclusive dermatologic care) wants to help expand our knowledge.

“Dandruff is white to yellowish, dry or oily flaking that occurs due to an increased turnover rate of dead skin cells on the scalp,” she explains. “It can be itchy, but lacks inflammation such as redness—unlike seborrheic dermatitis, a similar but much more severe condition, which tends to affect other areas of the body beyond the scalp.”

Causes


Now that you’re refreshed on the what, let’s go over the why. Keep reading for seven common causes of dandruff.


An Overgrowth of Fungus: According to Kikam, the most common cause of dandruff is related to the overgrowth of Malassezia yeast (a naturally-occurring fungus) on the scalp. “Malassezia yeast is part of normal skin flora but it can sometimes grow out of control, causing dandruff,” she explains.


Overproduction of Sebum: As Kikam points out, Malassezia yeast feeds on sebum. As such, the overproduction of sebum (read: scalp oil) is another common cause of dandruff.


Genes: According to a 2015 review published in the Journal of Clinical and Investigative Dermatology, researchers discovered that a disrupted barrier function can be passed down between generations, causing dominant and recessive forms of dandruff and it’s more severe cousin, seborrheic dermatitis.


Stress: According to the Mayo Clinic, signs and symptoms of dandruff grow more severe with stress.
Improper Scalp Care: Additionally, Kikam says that if you don’t regularly wash your hair and cater to your scalp, you can develop dandruff. That’s because the build-up of naturally-occurring oil can overwhelm your scalp and cause flaking.


Medical Conditions: If you have a weakened immune system or medical conditions such as Parkinson’s Disease, Kikam says that you could also be more at risk for dandruff.


Changes in the Weather: It’s not all medical, though. According to board-certified dermatologist Uchenna R. Okereke, MD, FAAD, who is a clinical associate at Harvard’s Mass General Hospital, drastic changes in weather can precipitate flares. “Flares usually occur during the change in weather from spring to summer or summer to fall,” she shares.

Treatments

While it’s helpful to know the most common causes of dandruff, Okereke says that it’s important to understand that there’s no cure for the flakes, “but with the right ingredients, it can be effectively managed,” she says. “Over-the-counter products and prescription medication are useful in targeting one of the most common culprits, yeast overgrowth, and preventing irritation to skin with the use of anti-fungal and anti-inflammatory ingredients.”


For noticeable results, Okereke suggests using medicated shampoos and lotions with ingredients like selenium sulfide, ketoconazole, zinc pyrithione, and coal tar, as they’re all effective in controlling flaking and itching associated with dandruff.
“Dermatologists can also prescribe prescription-strength concentrations of some of these ingredients, in addition to topical steroids that can significantly improve the condition when over-the-counter products don’t work,” she adds. “As always, reach out to your dermatologist if you experience any bleeding, redness, hair loss, or pain to the scalp.”