What Is Scalp Malassezia? Exploring the Fungal World of the Scalp Microbiome

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It might start with a small bump or a dry patch on an otherwise healthy scalp. But when you're dealing with a disruption to the microbiota of the scalp or hair follicle, a dramatic little yeast called Malassezia globosa can go nuclear and wreak complete havoc on your head. According to Dhaval Bhanusali, MD, a board-certified dermatologist and founder of Hudson Dermatology & Laser Surgery and Skin Medicinals, it can be linked to conditions as mundane as everyday folliculitis (an infection around the hair follicle) all the way to seborrheic dermatitis (a form of eczema).

While Malassezia exists on everyone's scalps, studies show that roughly half the population suffers from an underlying sensitivity to it. This sensitivity then leads to the flaky, itchy, dry, inflamed scalp condition known as dandruff. In certain conditions, things can take a turn for the more serious, when itchiness becomes painful, patches become inflamed, and plaques and lesions warrant a more serious diagnosis by the derm.

It all goes back to the balance of the scalp's microbiome, or microscopic makeup of flora. "The scalp has a very high volume of vitamin-rich sebum production coming from the sebaceous glands in the hair follicles, and this very humid environment gives rise to bacteria, biofilm, fungus, and microbes not found anywhere else on the body," says Lars Skjoth, head scientist and founder of hair brand Harklinniken. There are a number of factors that can lead to an imbalance in the scalp and follicle's unique microbiome, and the presence and buildup of sebum, or oil, which the yeast feeds on, is like adding fuel to the fire.

Here's everything you need to know about scalp Malassezia, including how to treat the condition.

What is Malassezia?

"Malassezia, a natural part of the scalp microbiome, is a monophyletic genus of fungi responsible for fueling the skin's growth cycle," says Skjoth. When there is an excess of sebum, which can be caused by a number of factors — a hormonal shift, a change in diet, you begin working out and sweating more, or perhaps hair dye on your scalp — the Malassezia, which feeds off of the oil, goes into overdrive. This is problematic for those of us that are sensitive to the yeast as "overgrowth can cause scalp irritation and lead to rapid cell turnover as the body tries to dispose of the irritant." (In other words, flakes, plaques, and excess oil.)

These triggers can thus cue the exacerbation of symptoms into flares of more serious conditions as dry patches become itchy-yet-painful, flaking plaques develop, the scalp becomes red and inflamed, and oiliness, hair breakage, dullness, and thinning occur in time. By cuing disruptions at the microscopic level, more serious presentations of seborrheic dermatitis, atopic dermatitis (or eczema), and psoriasis may be diagnosed. And it all comes back to that pesky little fungus.

How to Treat Scalp Malassezia

The first step is to ensure you are not suffering from dry scalp due to drying products or chemicals, or potentially even a flaking condition like psoriasis, by getting it checked out by an expert. "There are several ways to treat an imbalance on the scalp from medicated shampoos, to scalp-targeted products, to prescription medications, depending on severity," says Lan Belinky, co-creator and general manager of boscia. Dr. Bhanusali notes that derms often prescribe and recommend "selenium sulfide, ketoconazole, and zinc pyrathione" to help treat the underlying infection, while products containing salicylic acid help with the flakes.

Trying to treat the inflammation, flaking, and imbalance on your own can be challenging, particularly because so many products and oils that would otherwise be great for your hair and scalp can exacerbate the imbalance by feeding the Malassezia — particularly with the inundation of scalp health products that have come onto the scene in the last year. "We see this problem in particular with coconut oil," says Dr. Bhanusali.

Maintenance and prevention requires tending to the scalp microbiome. Harklinikken Stabilizing Shampoo ($54) or Harklinikken Balancing Shampoo ($54) was developed to treat the scalp microbiome daily while removing excess oil and buildup, and they also create custom essences for their clients. Natural beauty shoppers can look for options that contain the anti-fungal tea tree oil, soothing aloe, pH-balancing apple cider vinegar, calming colloidal oat, and Willow Bark, as found in Dermazen Cleansing Dandruff Shampoo ($50) and Dermazen Calming Seborrheic Serum ($40).

Chronic sufferers of seborrheic dermatitis swear by shampoos like Ducray Kelual DS, ($26), and the Flexitol Scalp Relief Shampoo and Conditioner, ($14). A mild flare might benefit from a product like Boscia Probiotic Exfoliating Powder Face + Scalp ($38), but at its worst, the condition can be so painful, uncomfortable, and recurrent, that it is tempting to consider the anti-inflammatory and healing effects of a red light LED device for the scalp. Options like Kiierr Laser Cap ($695-$1,045) or the Capillus Pro Hair Regrowth Cap, ($2,000) feature little tines to get the light from the bulbs around the hair and onto the scalp.

The Case for Ongoing Scalp Care

Maintaining your yeast-balanced scalp will vary depending on what caused the flare, whether it's from travel, working out, a biological factor, or even from a change in the seasons. Because the condition can result in hair thinning and even loss (it is not uncommon to have small patches go temporarily bald in little patches), Skjoth urges to care for your scalp as meticulously as you do for your face. He points out that it ages more rapidly and has less of a protective barrier function, rendering it more vulnerable to irritation.

He says to stop using dry shampoos and to get used to washing everyday using the right kind of shampoo, as well as omit certain ingredients — like perfume, sodium lauryl sulfate (SLS), sodium laureth sulfate (SLES), diethanolamine, butylparaben, to name a few — from your product regimens.

Because hair dye can also be a trigger, Skjoth provides some guidelines on how to do damage control. "Using hair dye that is free of ammonia and hydrogen peroxide will be safer for your scalp and hair follicles," he says, adding to be wary not to let the dye sit on your scalp if possible. "Also, giving your hair time to breathe before appointments will help keep the scalp from drying out." If you need a few options, celebrity colorist Tania Whittier specializes in O&M hair dye, which are some of the gentlest on the market, while another option to seek out is the French brand Vegetalement.

All that's left to do now is to get your scalp regimens started, always keeping in mind that all roads lead back to the scalp microbiome.