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Seborrheic dermatitis: Causes

Some people have a higher risk of developing seborrheic dermatitis

More than half the people living with Parkinson’s disease, which affects the brain’s ability to control movement, develop the greasy, scaly patches of seborrheic dermatitis.

Man with Parkinson’s disease steadying his hand so he can eat soup

What causes seborrheic dermatitis?

Exactly what causes this skin disease is unknown. Dermatologists believe that the following play a role:

  • Yeast that lives on everyone’s skin

  • Sebum (an oil that our skin makes)

If you have seborrheic dermatitis, it may be that you’ve developed a reaction to the yeast on your skin. This reaction then causes the rash.

There are some findings to support this. One medication that dermatologists use to treat seborrheic dermatitis is an antifungal. Yeast is a fungus, so the antifungal medication removes some yeast from the skin.

When people with seborrheic dermatitis have less yeast on their skin, they get relief from symptoms. Some people even see their skin clear for a while. When the yeast starts growing again, the seborrheic dermatitis returns.

It’s likely that sebum also plays a role in this reaction. We know that seborrheic dermatitis develops at times in our lives when the body makes more sebum. We also know that this disease develops on skin that contains the most sebum like the scalp, face, and chest.

Dermatologists believe that the yeast feed on the sebum, which allows them to grow.

After reading this, you may think that you need to wash more often, or that seborrheic dermatitis is an allergy. While the exact cause is still a mystery, dermatologists have learned that seborrheic dermatitis is:

  • NOT caused by unclean skin

  • NOT an allergy

What increases the risk of developing seborrheic dermatitis?

While everyone has this yeast on their skin, only some people develop seborrheic dermatitis.

To be sure, many people who have seborrheic dermatitis are otherwise healthy. However, having a certain medical condition greatly increases the risk of developing seborrheic dermatitis. These conditions include:

  • Some neurologic disorders, such as Parkinson’s disease and epilepsy

  • HIV infection

  • Having had an accident that affects the brain or injures your spinal cord

  • Lymphoma (a type of cancer)

  • A mood disorder like depression

  • Down syndrome

  • Anorexia nervosa (an eating disorder)

  • Heavy alcohol consumption

  • Rosacea or psoriasis

  • Stroke or heart attack (recovering from)

You also have a higher risk if you received an organ transplant.

During warm, humid weather, many people find that seborrheic dermatitis lessens or goes away

When cold, dry weather returns, it can trigger flare-ups.

Smiling man riding a bicycle on a warm summer day

Taking certain medications also increases the risk

Some people develop seborrheic dermatitis or see their seborrheic dermatitis flare up after taking a prescription medication. The medications linked to seborrheic dermatitis are oral (take by mouth) and include:

  • Auranofin - Prescribed for rheumatoid arthritis.

  • Fluorouracil - Prescribed to treat cancer.

  • Griseofulvin - Prescribed to treat fungal infections.

  • Haloperidol - Prescribed to control symptoms of Tourette's disorder and to treat schizophrenia and other conditions that affect a person’s mental health.

  • Lithium - Prescribed to treat bipolar disorder (manic-depressive illness).

  • Psoralen - Taken before you have a light treatment called PUVA, which is sometimes prescribed to treat psoriasis.

When seborrheic dermatitis flares, treatment can help control it so that you have fewer flare-ups. To find out how dermatologists treat this disease, go to Seborrheic dermatitis: Diagnosis and treatment.

Getty Images

Borda LJ, Wikramanayake TC. “Seborrheic dermatitis and dandruff: A comprehensive review.” J Clin Investig Dermatol. 2015 Dec;3(2):10.13188/2373-1044.

Reider N, Fritsch PO. “Other eczematous eruptions.” In: Bolognia JL, et al. Dermatology. (fourth edition). Mosby Elsevier, China, 2018: 228-30.

Rietcheck H, R, Maghfour et al. “A review of the current evidence connecting seborrheic dermatitis and Parkinson’s disease and the potential role of oral cannabinoids.” Dermatology 2021;237:872-7.

Written by:
Paula Ludmann, MS

Reviewed by:
Dara D. Spearman, MD, FAAD
Elaine T. Kaye, MD, FAAD
J. Klint Peebles, MD, FAAD

Last updated: 12/6/22