Malassezia Yeast and Seborrheic Dermatitis: What the Research Shows

What is Malassezia?

Malassezia is a genus of yeast that lives naturally on the skin of nearly every healthy adult, particularly in oil-rich areas like the scalp, face, and upper back. It is considered a normal part of the skin's resident microbial community — its presence alone is not a sign of disease.

A yeast, not a bacteria

Malassezia is a fungus, not a bacterium. It's a common point of confusion because many skin conditions are bacterial, but seborrheic dermatitis is associated with a fungal (yeast) organism, which is why the first-line treatments are antifungal shampoos and creams rather than antibiotics.

What it feeds on

Unlike most yeasts, Malassezia species can't produce their own fatty acids — they depend on external lipids to survive, which is why they cluster in sebum-rich areas of the body. They break down components of sebum, and some of the byproducts of that process are thought to irritate skin and trigger the inflammatory response seen in seborrheic dermatitis, rather than the yeast itself directly damaging skin cells.

The association with seborrheic dermatitis

Malassezia is consistently found in higher relative abundance on skin affected by seborrheic dermatitis, and antifungal treatments that reduce it often improve symptoms — one of the main reasons researchers consider it a central factor. Several species within the genus have been implicated, most often M. globosa and M. restricta, though exactly which species dominate can vary between individuals and body sites.

Malassezia folliculitis vs. seborrheic dermatitis

Malassezia folliculitis is a separate condition caused by the same yeast genus, but it looks and behaves differently: it presents as small, itchy, acne-like bumps around hair follicles, typically on the chest, back, and shoulders, rather than the flaking and redness typical of seborrheic dermatitis. The two are sometimes confused because they share a fungal cause and can occur in the same person, but they're treated as distinct diagnoses.

How treatments target it

Many first-line over-the-counter and prescription treatments work in part by reducing Malassezia populations — ketoconazole, zinc pyrithione, selenium sulfide, and ciclopirox are all antifungal or antimicrobial agents — or by calming the inflammatory response it triggers. See our full treatments guide for how these are typically used together.

Open questions

It's not fully settled why some people with similar amounts of Malassezia develop symptoms while others don't — individual immune and skin-barrier differences are an active area of study, which is why seborrheic dermatitis is increasingly described as a combination of factors rather than a single-organism disease. See our deep dive on why single-cause explanations fall short.