Fungal acne checker
and what the lab tests found

What fungal acne is

"Fungal acne" is the common name for Malassezia folliculitis: a yeast called Malassezia growing in hair follicles. In a study of 49 people with it, M. globosa was the species found most often (Durdu 2013, abstract only). M. globosa can't make its own fatty acids, so it breaks down skin oils to get them (Xu 2007). That is why fungal-acne lists focus on oils and fats.

It can look like regular acne, so a doctor needs to check. This page doesn't diagnose anything.

How to read the results

• Fed the yeast in a lab test: at least one strain grew when this ingredient was its only food.
• A little growth: a study saw only limited growth.
• No growth in the lab tests: no strain grew on it. That is a lab result, not a promise about your skin, so we never call an ingredient "safe".
• Not tested: neither study tested it. That doesn't mean it can't feed the yeast.

Every result names the species, so look at M. globosa first. In Dobler 2019, M. furfur grew on 43 of the 65 ingredients we use and M. globosa on 29, so a result where only M. furfur grew says less. Liebregts 2025 tested M. furfur and M. pachydermatis, which the authors describe as often found on animal skin.

Popular rules, checked

• "Mineral oil is fine." In Dobler 2019, M. furfur grew on mineral oil (paraffinum liquidum), though slowly; the other species didn't. Another study found M. furfur grew with white petrolatum (Koyama 2002, abstract only).
• "MCT oil is fine." No strain grew on caprylic/capric triglyceride in Dobler 2019. A study of fats drip-fed into a vein found medium-chain triglycerides held back M. furfur at 50% and M. sympodialis at 8% (Papavassilis 1999, abstract only), but that wasn't skincare.
• "All esters feed it." It depends on the ester. Isopropyl myristate and isopropyl palmitate fed every strain; cetearyl isononanoate fed none (Dobler 2019). An older study found the yeast broke down ethyl and isopropyl esters most easily (Mayser 1995, abstract only).
• "Polysorbates feed it." Both studies saw growth on polysorbate 80 (Tween 80) and polysorbate 40 (Tween 40), at the strengths they tested.
• "Squalane is fine." We haven't found a study that tested squalane.

"Abstract only" means we have read only the summary, so its findings don't count in the checker.

What the lab tests can't tell you

• A dish is not your skin. In the lab, the ingredient was the yeast's only food. On skin, the yeast also has your own oils, and many other microbes.
• No study in people. We haven't found any study that links a skincare ingredient to fungal acne in people.
• The amount matters. The tests used raw ingredients, at strengths that may differ from a finished product.

Questions