Paste an ingredient list into the box below and pick what you’re checking for. Malassezia (the yeast linked to fungal acne and seb derm), rosacea, or pore-clogging (comedogenic) ingredients. The checker reads every single ingredient and highlights the ones worth a second look, with a quick line on why.
It uses the same rules I screen products with for my seb derm directories. That makes it a little strict on purpose (I’d rather flag something and let you decide). A flag is only a heads up though. Loads of people use flagged products and get on fine with them, so patch test and trust your own skin.
How the checker decides what to flag
Fungal acne and seb derm (malassezia)
For malassezia, red means ingredients the yeast is known to feed on. Thats most plant oils and butters, plus fatty acids and the esters made from them in the C11 to C24 range (laurates, stearates, palmitates, oleates) and polysorbates. Amber means the evidence is thinner or the checkers don’t agree. Fatty alcohols, ferments and lecithin all land there.
Cetearyl alcohol is the tricky one. A 2019 lab study by Dobler and colleagues saw some malassezia growth on it, especially from one species (M. furfur). SkinSort and Folliculitis Scout both flag it, but that one lab study is most of the evidence, so I mark it amber and you make the call.
Essential oils don’t get flagged in malassezia mode. They’re mostly terpenes rather than the fats in carrier oils, so they aren’t counted as yeast food. Flip over to rosacea mode and they light up.
Seb derm and fungal acne share the first button because they’re driven by the same yeast, so the same ingredients get flagged for both. For a seb derm scalp, the leave-in products are the ones worth checking hardest, because a shampoo rinses off in a minute and a serum sits there all day.
Rosacea triggers
For rosacea, the list comes from National Rosacea Society patient surveys and the American Academy of Dermatology’s rosacea advice. Alcohol, fragrance, witch hazel and menthol came out on top, with peppermint and eucalyptus close behind, so those are red. Amber covers the stuff that bothers some people and not others, like exfoliating acids, sulfates, dyes and fragrance allergens such as linalool and limonene.
Everyone’s rosacea is different, so your own triggers might not be on here at all. You might sail through half the red ones too.
Pore-clogging (comedogenic) ingredients
For pore clogging, red means the ingredient was named as an offender in rabbit ear studies by dermatologist James Fulton and colleagues, mostly esters like isopropyl myristate, isopropyl palmitate and ethylhexyl palmitate, plus cocoa butter and acetylated lanolin. Amber covers oils like coconut, wheat germ and apricot kernel that showed up in the early tests but have less behind them. These ratings come from rabbit ears, which Fulton himself called not an ideal model, and a finished product can behave differently to a single ingredient. So treat this mode as a rough guide, not a verdict.
Get the best result
Copy the list off the actual box if you can. Retailer pages and ingredient sites sometimes show an older formula, and I’ve found two different ingredient lists online for the same scalp serum, so the box wins every time.
Paste the whole thing and separate it however you like. Bits in brackets like Aqua (Water) stay together.
It can’t diagnose anything (it just reads labels). If your skin’s flaring and nothing seems to help, a GP or dermatologist is your best bet.
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Sources the checker is built on
Every red and amber reason in the checker comes from one of these, or from the rules explained above. Tap the button to see them all, grouped by checker mode.
Show all 16 sources
Fungal acne and seb derm (Malassezia mode)
- Dobler D, Schmidts T, Wildenhain S, Seewald I, Merzhäuser M, Runkel F. Impact of Selected Cosmetic Ingredients on Common Microorganisms of Healthy Human Skin. Cosmetics, 2019 – the lab study behind the cetearyl alcohol and hydrogenated castor oil results
- SkinSort: Fungal Acne (Malassezia) Ingredient Checker – the C11 to C24 fatty acid rule, fatty alcohols and ferments
- SkinSort: Seborrheic Dermatitis Ingredient Checker – why seb derm and fungal acne share the same trigger list
- Folliculitis Scout: Cetearyl Alcohol – its list of flagged ingredients, including polysorbate 20 and PEG hydrogenated castor oils
- Simple Skincare Science: Fungal Acne Safe Products – lecithin, and why essential oils are treated differently to carrier oils
Rosacea
- National Rosacea Society: Ingredients May Aggravate Rosacea – alcohol, witch hazel, fragrance, menthol, peppermint and eucalyptus oil
- National Rosacea Society: Rosacea Awareness Month Calls for Holistic Approach (2025) – dyes, sulfates and parabens or other preservatives
- National Rosacea Society: Rosacea Skin Care and Cosmetics – exfoliating agents, harsh products, and the American Academy of Dermatology on fragrance allergy
- American Academy of Dermatology: 7 Rosacea Skin Care Tips Dermatologists Recommend – alcohol, camphor, fragrance, glycolic and lactic acid, menthol, sodium lauryl sulfate and urea
- American Academy of Dermatology: Rosacea Diagnosis and Treatment – benzoyl peroxide on sensitive skin
- American Academy of Dermatology: Acne Diagnosis and Treatment – retinoid side effects and how to reduce them
- EU Commission Regulation 2016/1198 – the ban on methylisothiazolinone in leave-on cosmetics
- Dr Leslie Baumann, Skin Type Solutions: Best Vitamin C Serums for Rosacea – why acidic L-ascorbic acid can irritate rosacea-prone skin
Pore clogging
- Fulton JE Jr, Pay SR, Fulton JE 3rd. Comedogenicity of current therapeutic products, cosmetics, and ingredients in the rabbit ear. J Am Acad Dermatol, 1984 – the named pore-clogging esters
- Comedogenicity in rabbit: some cosmetic ingredients/vehicles (PubMed) – cocoa butter and the esters that tested positive, and cetyl alcohol, stearyl alcohol and petrolatum, which did not
- JAAD Reviews: Comedogenicity in cosmeceuticals, a review of clinical relevance, 2025 – coconut, wheat germ and apricot kernel oils, acetylated lanolin, and the history of the rating scale
