Are Comedogenic Ratings of Oils Reliable?

Comedogenic ratings of oils aren't reliable enough to predict whether an oil will clog your pores. The familiar 0-to-5 numbers combine different species, test sites, concentrations and scoring methods. Many ratings came from neat ingredients placed under occlusion, not everyday facial use. Treat the number as a warning flag, not a verdict. The finished formula and your own response matter more.

Why the 0-to-5 scale looks more precise than it is

Comedogenicity means the ability to promote comedones, the plugs behind blackheads and whiteheads. Most tests count microscopic plugs called microcomedones. They don't directly measure every kind of breakout, such as inflamed papules or cysts.

The oldest ratings often came from rabbit ears. Kligman and Kwong's 1979 British Journal of Dermatology method applied test materials for two weeks. Researchers then removed the ear skin and counted microcomedones under a microscope. That model was fast and sensitive, but a rabbit ear isn't a human face.

In a 1982 Archives of Dermatology study, Mills and Kligman tried to close that gap. Their human model placed substances under occlusion for one month on the upper backs of young adult Black men with large follicles. It found that moderate or strong rabbit-ear positives could also form human comedones. Yet the authors said the rabbit model was more sensitive. Weak rabbit-ear positives were probably safe for most people.

Those details matter. Occlusion traps a substance against skin. The back differs from the face. A pure oil differs from a small amount inside an emulsion. Even the outcome varies between visible spots and microscopic plugs.

Starzyk and colleagues reviewed the field in JAAD Reviews in 2025. They found no standardized test behind the term or the popular rating charts. That means a “2” from one list isn't necessarily comparable with a “2” from another.

What direct tests of facial oils can tell you

Verallo and Verallo-Rowell published a double-blind study in the Journal of the Philippine Dermatological Society in 2024. They tested ten pure cosmetic oils on 30 Filipino adults. Patches stayed on the back and were changed three times weekly for four weeks. Almond oil increased the microcomedone count by 112.9% from baseline.

That finding is useful but narrow. It shows almond oil formed microcomedones under that study's conditions. It doesn't create a universal rating for every almond oil product. The trial used a pure oil, repeated occlusion, back skin and a small group. A rinse-off cleanser or dilute moisturizer creates a different exposure.

Finished-product studies show why ingredient scores can mislead. Draelos and DiNardo tested finished cosmetics on six people for four weeks. Their 2006 study appeared in the Journal of the American Academy of Dermatology. Products containing ingredients previously called comedogenic weren't necessarily comedogenic as formulas.

Waranuch and colleagues reported a similar result in Contemporary Clinical Trials Communications in 2021. Twelve men completed analysis of finished products containing ingredients that included avocado and sunflower oils. Each product stayed below the study's 50% microcomedone threshold. The positive control, octyl palmitate, increased counts by an average 365.4%.

That trial was also small and used occluded back patches. It doesn't prove those oils suit everyone. It does show why you can't transfer a raw ingredient's score straight to a mixed product.

What changes an oil's real-world risk

• Concentration: a neat face oil gives much more exposure than a small percentage inside a lotion formula.

• Vehicle: an oil behaves differently inside a cream, gel, balm or cleanser. The whole formula controls spread, contact and removal.

• Contact time: a rinse-off product isn't comparable with a four-week occlusive patch.

• Test site: rabbit ears and human backs don't reproduce facial follicles, sebum or daily cleansing.

• Your skin: a chart doesn't include your acne history, current treatments or the rest of your routine.

• The outcome: microcomedones under a microscope aren't the same as visible inflammatory acne.

Oil type still matters, but chemistry doesn't give a certain personal answer. A high rating can flag a reason for caution. A low rating can't guarantee clear skin.

A better way to make the product decision

How to use an oil rating without letting it make the decision

Situation	What the rating tells you	Better next step
You're considering a pure, leave-on facial oil	The ingredient rating is more relevant here, but the original test may still use another species or body site.	If you often get closed comedones, skip an optional high-rated oil. Choose a finished moisturizer made for acne-prone skin instead.
An oil appears in a finished cream	The raw oil's number can't predict the mixed formula.	Look for finished-product human testing when the brand provides it. Use a non-comedogenic claim only as a screening clue, not a guarantee.
The product rinses off	A leave-on or occlusive rating overstates how closely the test matches your use.	Judge the complete cleanser and how your skin responds. Don't reject it from one ingredient score alone.
You started several products and developed bumps	No chart can identify the cause from a multi-product change.	Return to your last tolerated routine. Reintroduce optional products one at a time after your skin settles.
You already have persistent acne	An oil rating says nothing about whether the product treats acne.	Use an acne plan with clinical evidence. Keep moisturizing separate from treatment decisions.

If a label is your main clue, read our guide to what a non-comedogenic claim can and can't establish. It explains the finished-product label without turning it into a promise.

You can run a simple editorial check at home, but it isn't a validated comedogenicity test. Add only one optional product while keeping the rest of your routine stable. Use it as directed. Human assays usually ran for four weeks, so one clear morning tells you little. Stop sooner for burning, swelling or a marked increase in spots. No change means you tolerated that product during the trial. It doesn't prove the oil is safe for everyone.

If you're trying to clear acne, don't build the plan around oils

Comedogenicity tests assess pore plugging. They don't show that an oil prevents or treats acne. A low score is a tolerance claim at best, not proof of effectiveness.

The American Academy of Dermatology published its updated guideline in its journal in 2024. It strongly recommends benzoyl peroxide and topical retinoids among its acne options. It conditionally recommends salicylic acid and azelaic acid. Those recommendations come from treatment evidence, not ingredient rating charts.

If benzoyl peroxide fits your situation, our practical benzoyl peroxide guide explains how to limit irritation. Keep expectations realistic. The guide to how long acne treatments take helps you avoid abandoning a sound routine after a few days.

See a dermatologist if acne is painful, deep, scarring or persistent despite consistent over-the-counter care. Bring the products you use, not screenshots of oil ratings. The actual formulas, timing and pattern of breakouts are more useful.