Does cleansing oil actually clog pores?

Every oil has a comedogenic rating attached to it somewhere — a number from 0 to 5 that tells you whether to worry.

The comedogenic ratings behind the worry about cleansing oil come from a rabbit ear. A human version of the test exists, but it works by holding an occlusive patch against the upper back for a month. Rinse-off products have been tested — but never rinsed. No published study has measured comedones under the condition that defines the product: a minute on the face, then washed off.

Where does the "comedogenic" rating come from?

In the reference method, test materials are applied for two weeks to rabbit ears just outside the ear canal; the excised tissue is then immersed in 60 °C water for two minutes, which lifts off a sheet of epidermis with the microcomedones attached, and follicular hyperkeratosis is graded under a stereomicroscope (Kligman & Kwong, 1979).

What the rabbit ear assay measures is follicular hyperkeratosis on the inner skin of a rabbit's ear over two weeks. It is not what happens in a pore on a human face.

What does the human comedogenic test measure?

The human comedogenic test occludes the back for weeks. It applies substances for a month to the upper back of young Black men chosen for their large follicles, then lifts the follicular contents with fast-setting cyanoacrylate glue for grading (Mills & Kligman, 1982).

The people who say not to read the back-patch method that way are the ones who sell the test. In a paper on how non-comedogenic claims are substantiated, researchers at a contract testing laboratory wrote that this follicular biopsy method "has never been validated against an in-use clinical trial, the gold standard," and that the data it generates should not be used to claim non-comedogenicity (Weiss & Caswell, 2017).

Has anyone tested a rinse-off product like cleansing oil?

In 1975 Mills and Kligman assayed popular soaps and shampoos on rabbit ears (Mills & Kligman, 1975), and in 2026 a facewash was tested on human backs under an occlusive patch for a month (Gala et al., 2026). The facewash study diluted the product and did not report the dilution. It is not that rinse-off products have gone untested; it is that rinsing has.

The phrase Korea's regulator lists for substantiation is not "non-comedogenic" but suitable for acne-prone skin, with the comedogenicity test serving as the evidence behind it rather than as the claim itself. The guideline offers a standard method: twenty or more people aged 14 to 40, three sites marked on the upper back for untreated, positive control and test material, and occlusive patches three times a week for four weeks — twelve applications in all (MFDS substantiation testing guideline, 2018).

Does cleansing oil "oxidise and clog pores"?

Squalene peroxides were highly comedogenic on rabbit ear skin (Motoyoshi, 1983).

The human evidence only shows oxidised squalene and acne appearing together, and it is about your own sebum rather than anything you applied. In a preliminary study of 15 people, total squalene measured 174.1 µg per strip in acne-prone skin against 37.0 in healthy skin, and peroxide forms reached 7.3% on the forehead of acne patients while none were detected in the healthy volunteers at all (Condrò et al., 2023). Oxidised squalene is found more in acne-prone skin; no study has applied a cleansing oil and then measured comedones. What decides pore size is taken up in why large pores and blackheads keep coming back.

What the evidence leaves you with on cleansing oil

What is mismatched about cleansing oil is not the ingredient but the condition. Whether the label says "non-comedogenic" or "suitable for acne-prone skin," take it off your list of reasons to buy a rinse-off product.

One step today

• Drop "non-comedogenic" — and its Korean equivalent, "suitable for acne-prone skin" — from how you choose a rinse-off product. The test behind either one held the product on the back for four weeks rather than rinsing it off a face (MFDS substantiation testing guideline, 2018). Set no waiting period. You have done it when a bottle without the label stays on your shortlist.
• Judge after the rinse instead: does the skin feel tight, and is there a slippery film left behind. The facewash was not rinsed either (Gala et al., 2026). Set no waiting period; check at the basin, every wash. Those two signs are enough.
• If you want to test a cleansing oil, change one product and give it four weeks. The test that graded comedones also kept the material on the back for a month (Mills & Kligman, 1982). If no new comedones have appeared by week four, keep using it.