What Triggers Fungal Acne in Skincare?

What Is Fungal Acne?

Fungal acne, clinically known as Malassezia folliculitis(previously called Pityrosporum folliculitis), is a skin condition caused by an overgrowth of Malassezia yeast in the hair follicles. Despite its common name, it is not true acne at all. While conventional acne (acne vulgaris) is caused by the bacterium Cutibacterium acnes, fungal acne is a fungal infection.

Malassezia is a genus of yeast that naturally lives on human skin. In healthy amounts, it causes no problems. However, when conditions favour its overgrowth — such as humidity, sweating, occlusive clothing, antibiotic use, or a weakened immune system — it can infiltrate hair follicles and cause inflammation.

How Fungal Acne Differs from Regular Acne

Recognising the difference between fungal acne and bacterial acne is important because they require different treatments. Here are the key differences:

Which Ingredient Types Feed Malassezia?

Malassezia yeast is lipid-dependent, meaning it requires fats and oils to grow. However, it cannot use all lipids equally. Research has shown that Malassezia preferentially metabolises specific types of fatty acids and their derivatives:

• Fatty acids with carbon chain lengths C11–C24. These medium- to long-chain fatty acids are the primary food source for Malassezia. Common examples include oleic acid (C18:1), lauric acid (C12), myristic acid (C14), palmitic acid (C16), and stearic acid (C18).
• Esters derived from these fatty acids. When a fatty acid is bonded to an alcohol, it forms an ester. Many common skincare ingredients are esters, such as isopropyl myristate, isopropyl palmitate, and glyceryl stearate. Malassezia has lipase enzymes that can break these esters back down into their component fatty acids.
• Oils high in oleic acid. Many plant oils are rich in oleic acid, which Malassezia readily metabolises. These include olive oil, sweet almond oil, avocado oil, and marula oil. Oils lower in oleic acid (such as MCT oil with only C8 and C10 chains, or squalane) are generally better tolerated.
• Polysorbates. These emulsifiers (Polysorbate 20, 60, 80) contain fatty acid chains that can feed Malassezia.
• Fermented ingredients and galactomyces. Some fermented filtrates may contain metabolites that promote Malassezia growth, though evidence here is more limited and anecdotal.

How to Identify FA-Safe Products

Finding fungal acne safe products requires checking every ingredient against a reliable database. Here are some practical steps:

1. Use an ingredient checker. Paste the full ingredient list into the DermLabs checker to instantly flag any Malassezia-feeding ingredients.
2. Look for simple formulations. Products with shorter ingredient lists are easier to vet and less likely to contain hidden triggers.
3. Favour mineral and silicone-based products. Mineral sunscreens, silicone-based primers, and oil-free moisturisers are often FA-safe by default.
4. Check oils carefully. Not all oils trigger fungal acne. Squalane, MCT oil (caprylic/capric triglyceride with only C8/C10 chains), and mineral oil are generally considered safe.
5. Browse our FA-safe ingredient list. Our curated list of fungal acne safe ingredients can help you identify products that are likely to be well tolerated.

Keep in mind that fungal acne can be tricky to self-diagnose. If your breakouts are not responding to conventional acne treatments, or if they are itchy and uniform in appearance, consider seeing a dermatologist who can confirm the diagnosis, sometimes with a simple skin scraping examined under a microscope.