Dandruff occurs, essentially, when small bits of dry skin are shed from the scalp. You might spy these flakes in your hair or on your shoulders. Dandruff may make your scalp itchy, too. It’s a common problem, but it isn’t as simple as it seems. Dandruff is actually quite tricky to define because it overlaps with seborrheic dermatitis (a chronic form of eczema) and other skin conditions that lead to a scaly scalp. Here’s what you need to know.

Causes and Risk Factors of Dandruff

Dandruff can happen for a number of reasons:

Seborrheic Dermatitis If you have a particularly bad case of dandruff, it’s likely a mild case of seborrheic dermatitis (SD), according to the American Osteopathic College of Dermatology.SD is a chronic form of eczema that impacts areas of the body that secrete the most sebum, or oil, notes the National Eczema Association.
People with oily skin are often more prone to dandruff. The reason: A yeast called Malassezia globosa feeds on oils on the scalp. Some people’s bodies perceive this breakdown of oil as an irritant, so the scalp reacts by upping the speed at which skin cells renew, causing dandruff, notes Amy McMichael, MD, professor of dermatology and chair of the department of dermatology at Wake Forest School of Medicine in Winston-Salem, North Carolina. For those without dandruff, it takes a whole month for new skin cells on the scalp to mature, die, and shed. But for those with dandruff, this process occurs in a mere two to seven days, according to a report in the Journal of Medical Chemistry.
Still, it's important to note that while M. globosa has long been thought to be the main risk factor for dandruff, a causal relationship has yet to be firmly established, noted a July 2019 report in the journal Experimental Dermatology.
Contact Dermatitis Contact dermatitis is skin irritation caused by either an allergen or an irritant, resulting in an itchy, possibly painful rash. And in the case of dandruff, that reaction is on the scalp. This generally occurs due to hair-care products or dyes, according to the American Academy of Dermatology Association.
Dry Skin If cold winter air dries out your skin all over, including your scalp, then dry skin may be the cause of your dandruff. When dry skin causes dandruff, the flakes are usually smaller and less oily than the flakes caused by SD, notes PIH Health.(In addition, cold and dry climates can also worsen SD, according to the Cleveland Clinic.)

Almost anyone can have dandruff, but certain factors can make you more susceptible, including:

Shampooing Habits “For those who are already at risk for dandruff, washing infrequently can worsen the condition,” says Dr. McMichael. Taking extended breaks can lead to a buildup of oil that can lead to dandruff.

Age Dandruff often begins at puberty and peaks around age 20, becoming far less prevalent among folks over 50 years old, according to a review published in December 2015 in the Journal of Clinical and Investigative Dermatology.
Sex Androgen hormones, such as testosterone, stimulate activity in the sebaceous glands. More oil means an increased chance of an inflammatory reaction and dandruff. Men are more frequently affected by dandruff than women.
Weakened Immune System SD is more prevalent in individuals who’ve undergone an organ transplant and those with HIV or AIDS, hepatitis C, or alcoholic pancreatitis. For example, 30 percent to 83 percent of those with HIV report SD.
Neurologic and Psychiatric Conditions Parkinson's disease, Alzheimer's disease, epilepsy, traumatic brain injury, and spinal cord injury are among the conditions that elevate one's risk of SD, including dandruff.Those with Parkinson's disease, for example, have an impaired autonomic nervous system that helps to control things like oil gland secretions, which can lead to an overproduction that leads to dandruff, according to the American Parkinson’s Disease Association.
History of Other Skin Disorders Having had eczema, rosacea, psoriasis, or acne can trigger or worsen seborrheic dermatitis.
Oily Skin If you have naturally oily skin, you’re at an elevated risk for seborrheic dermatitis.

Oiling Your Scalp “Certain oils applied to the scalp can cover the scale, but worsen the flaking and itching response,” notes McMichael.

Duration of Dandruff

Dandruff due to seborrheic dermatitis is a chronic condition that warrants repeated or long-term treatment. As for dandruff that arises from contact dermatitis, dry skin, or shampooing habits, changing habits can clear up flakes fairly quickly.

Prevention of Dandruff

“You can prevent the signs and symptoms of dandruff, but there is no cure for dandruff,” says McMichael. If you’ve got an especially oily scalp, daily shampooing with a gentle cleanser, coupled with a light scalp massage, may help prevent dandruff in certain cases. If you're using an OTC dandruff shampoo, talk to your dermatologist about how often to use for maintenance and prevention. Finally, upping your omega-3 intake, brief exposure to sun, and reducing the number of hair products used can help prevent dandruff, as well.

Research and Statistics: How Many People Get Dandruff?

Dandruff affects approximately 50 percent of the general adult population worldwide, according to past research.
Dandruff is more prevalent in males than females.

Resources We Love

Skin of Color Society

This professional dermatologic organization is dedicated to promoting awareness of (and excellence within) the dermatological care of skin of color. SCS offers a Find a Doctor database to help those of Asian, Hispanic or Latino, African, Native American, and Pacific Island descent find local dermatologists who are especially knowledgeable about their skin concerns. Whether you’re struggling to find a dermatologist who can help treat persistent dandruff in Black hair or you’ve got another skin-related issue, SCS’s Find a Doctor database can help.

American Academy of Dermatology

The AAD is the largest dermatology group in the United States and its website is full of resources, tips, and more. Curious how to ease your itchy skin? Check out their Everyday Care section. Craving some insider secrets to tackle your rosacea? Try the AAD’s Diseases and Conditions area. Not sure how to combat your child’s dandruff? Go to the areas dedicated to Parents and Kids.

Editorial Sources and Fact-Checking

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  • Seborrheic Dermatitis. American Osteopathic College of Dermatology.
  • Seborrheic Dermatitis. National Eczema Association.
  • Hewitson KS, Vullo D, Scozzafava A,et al. Molecular Cloning, Characterization, and Inhibition Studies of a B-Carbonic Anhydrase From Malassezia Globosa, a Potential Antifungal Target. Journal of Medical Chemistry. March 19, 2012.
  • Wikramanayake TC, Borda LJ, Miteva, M, Paus R. Seborrheic Dermatitis — Looking Beyond Malassezia. Experimental Dermatology. July 16, 2019.
  • 10 Reasons Your Scalp Itches And How To Get Relief. American Academy of Dermatology Association.
  • The Facts about Dandruff. PIH Health. April 12, 2019.
  • Seborrheic Dermatitis. Cleveland Clinic. May 29, 2020.
  • Borda LJ, Wikramanayake TC. Seborrheic Dermatitis and Dandruff: A Comprehensive Review. Journal of Clinical and Investigative Dermatology. December 2015.
  • Sweating and Other Skin Problems in People with Parkinson’s Disease. American Parkinson’s Disease Association. July 23, 2019.
  • Seborrheic Dermatitis Diagnosis and Tests. Cleveland Clinic. May 29, 2020.
  • Dandruff Diagnosis and Treatment. Mayo Clinic. September 11, 2019.
  • Dandruff. American Osteopathic College of Dermatology.
  • Dandruff Treatments. Northwestern Medicine.
  • Drugs and Supplements Ketoconazole (Topical Route): Description and Brand Names. Mayo Clinic. August 1, 2020.
  • Seborrheic Dermatitis: Management and Treatment. Cleveland Clinic. May 29, 2020.
  • What Is the Best Way to Treat Severe Dandruff? Harvard Health Publishing. May 2017.
  • Satchell AC, Saurajen A, Bell C, Barnetson RS. Treatment of Dandruff with 5 percent Tea Tree Oil Shampoo. Academy of Dermatology. December 1, 2002.
  • Barak-Shinar D, Green LJ. Scalp Seborrheic Dermatitis and Dandruff Therapy Using a Herbal and Zinc Pyrithione-Based Therapy of Shampoo and Scalp Lotion. The Journal of Clinical and Aesthetic Dermatology. January 2018.
  • Dandruff: What It Is and What to Do About It. Cedars Sinai. September 25, 2019.
  • Gathers RC, Mahan MG. African American Women, Hair Care, and Health Barriers. Journal of Clinical and Aesthetic Dermatology. September 2014.
  • Elewski BE. Clinical Diagnosis of Common Scalp Disorders. Journal of Investigative Dermatology Symposium Proceedings. December 1, 2005.
  • Cradle Cap (Seborrheic Dermatitis) in Infants. Kids Health. February 2019.
  • Ringworm (Scalp) Symptoms and Causes. Mayo Clinic. March 7, 2018.

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