Data study
Lists disagree because the old lab tests behind them often gave the same ingredient different scores, and lists copy those scores unevenly.
Drafted with AI research and edited by hand · Every number is worked out from our data files · Updated Nov 2, 2026
Two lab studies gave ingredients a score from 0 to 5: and . Both used the . They rated 20 of the same ingredients.
On this website, a score of 2 or more means a source flags the ingredient (more on ). The two studies agree on flag or no flag for 12 of the 20. They give the very same number for 5. For 7, their numbers are 2 or more points apart.
Fulton mixed nearly every ingredient to in . Morris and Kwan mostly used the ingredient pure, or undiluted: 15 of the 20 shared ingredients. For the rest, they used a mix, such as 50% in mineral oil.
The biggest gap is myristyl myristate: 5 in Fulton’s test and 0–1 in Morris and Kwan’s (50% in mineral oil).
Morris and Kwan wrote that labs get different results because of how they run the test, how pure the raw ingredient is, and how they grade it. Fulton found that the liquid an ingredient is mixed into changes the result, and he starred results that .
A 2006 study by Draelos and DiNardo put finished products on the upper backs of six people, three times a week for four weeks. Its authors concluded that products made with pore-clogging ingredients don’t always clog pores. We’ve read only its . Read it on PubMed.
A 2021 study by Waranuch and others ran a similar test on the backs of 15 men for four weeks. Finished products with a form of vitamin E and oils such as avocado and sunflower raised the count of tiny clogged pores by less than half, the study’s line for not pore-clogging. Octyl palmitate (ethylhexyl palmitate on labels), used as the known pore-clogger, raised it by more than half in each of the 12 men whose results were counted. Both studies above flag ethylhexyl palmitate. Read the full study.
Each study’s score exactly as printed, and what Morris and Kwan tested. Fulton tested all 20 at 10% in propylene glycol.
| Ingredient | Fulton 1989 | Morris & Kwan 1983 | Gap | Agree? | Acne Specialists list |
|---|---|---|---|---|---|
| Myristyl Myristate | 5 | 0–1 50% in mineral oil | 4 | no | names it |
| Avocado oil Persea Gratissima (Avocado) Oil | 3(2) | 0 undiluted | 3 | no | names it |
| Corn oil Zea Mays (Corn) Germ Oil | 3 | 0–1 undiluted | 2 | no | names it |
| Isodecyl Oleate | 2–3* | 1 undiluted | 2 | no | names it |
| Olive oil Olea Europaea (Olive) Fruit Oil | 2(1) | 0 undiluted | 2 | no | not listed |
| Safflower oil Carthamus Tinctorius (Safflower) Seed Oil | 0 | 1–2 undiluted | 2 | no | not listed |
| Sesame oil Sesamum Indicum (Sesame) Seed Oil | 3(1)** | 1 undiluted | 2 | no | names it |
| Acetylated Lanolin Alcohol | 4 | 4–5 undiluted | 1 | yes | names it |
| Ethylhexyl Palmitate | 4 | 2–3 undiluted | 1 | yes | names it |
| Glyceryl Stearate | 1 | 2 50% in mineral oil | 1 | no | names it |
| Isopropyl Isostearate | 5 | 4 undiluted | 1 | yes | names it |
| Isopropyl Linoleate | 4 | 4–5 undiluted | 1 | yes | not listed |
| Isopropyl Myristate | 5 | 3–4 50% in propylene glycol | 1 | yes | names it |
| Isopropyl Palmitate | 4 | 3 undiluted | 1 | yes | names it |
| Lanolin | 0–1* | 0 undiluted | 1 | yes | not listed |
| Castor oil Ricinus Communis (Castor) Seed Oil | 1 | 0–1 undiluted | 0 | yes | not listed |
| Decyl Oleate | 3 | 3 undiluted | 0 | yes | names it |
| Lanolin Alcohol | 0–2* | 1–2 30% in mineral oil | 0 | yes | not listed |
| Lanolin Oil | 0–1* | 0–1 and 1 undiluted | 0 | yes | names it |
| Polysorbate 20 | 0 | 0 1% aqueous | 0 | yes | not listed |
How to read Fulton’s numbers: a range like 0–2 is scored by its top number, a star (*) means the result depended on the supplier, and a number in brackets, like 3(2), is for the refined oil (** is his footnote on refined oils). “Agree?” means both flag it or neither does.
The last column shows whether the Acne Specialists list names each ingredient. It names 6 of the 8 that both studies flag, 6 of the 8 where they split, and 1 of the 4 that neither flags. We show only lists whose terms allow it.
Many popular lists give each ingredient a number and credit it to Fulton. We checked some of those numbers against the scanned pages of the papers.
Many lists rate coconut oil 4 and credit Fulton. His 1989 table has no coconut oil row. The 4 is on the row for coconut butter (rated 4 for clogging and 0 for irritation), on page 325. Morris and Kwan didn’t test coconut oil either. Fulton’s “coconut butter” can’t be pinned to one : it could be solid coconut oil, hydrogenated coconut oil or coconut seed butter. So we don’t count it as coconut oil.
Some lists rate algae extract 4 and credit Fulton. We read all 219 rows of his table and found no algae, seaweed or kelp. Morris and Kwan didn’t test any either. We couldn’t find where that 4 comes from, so we don’t use it.
Fulton’s 0 to 5 table, with a separate score for irritation, is in his 1989 paper in the Journal of the Society of Cosmetic Chemists (the Nov/Dec 1989 issue). Some sites credit those numbers to a different paper: Fulton, Pay and Fulton, 1984, in the Journal of the American Academy of Dermatology. We’ve read only that paper’s abstract, which names isopropyl myristate and similar ingredients, lanolins and D&C red dyes as pore-clogging in rabbits. When a list gives a Fulton number, check which paper it names.
The file lists every ingredient at least one of the two studies rated that we could match to one INCI name: 204 in all. Printed rows we couldn’t pin down are left out, such as Fulton’s “almond oil” (sweet or bitter not stated) and “coconut butter”. For each, it gives the INCI name, each study’s score exactly as printed, the number we use (the top of a range), what was tested, and how many of the studies that rated it flag it. Each row links to the paper its scores come from. It holds no data from published lists.
Download the CSV (204 ingredients)
Free to reuse. You may share and adapt it, in articles, apps or anywhere else, under CC BY 4.0. Credit “Acne Ingredient Checker” with a link to this page. The licence covers our compilation; the scores are from the two cited papers.
Cite as: Acne Ingredient Checker. Why pore-clogging lists disagree. https://acneingredientchecker.com/why-pore-clogging-lists-disagree, updated Nov 2, 2026.
Mostly because the lab tests behind them disagree. Two classic rabbit-ear studies rated 20 of the same ingredients and agreed on flag or no flag for 12. They tested different amounts, and lists copy their numbers unevenly, sometimes from the wrong row.
Neither is simply right. They tested the same ingredients in different ways: Fulton at 10% in propylene glycol, Morris and Kwan mostly undiluted. Fulton called the test very sensitive, and Morris and Kwan noted that rabbit and human pores differ. A flag is a reason to patch-test, not a verdict.
Yes. The CSV is free to use under CC BY 4.0. Credit Acne Ingredient Checker with a link to this page.
Our checker shows every source’s score for each ingredient, side by side, and how many agree. Paste a product’s ingredient list to see it.
Comedogenic
Likely to clog pores. A clogged pore is called a comedo: a blackhead or a whitehead.
Fulton 1989
James E. Fulton Jr., of the Acne Research Institute in California, rated about 220 skincare ingredients in 1989. Many pore-clogging lists still copy his numbers.
Morris & Kwan 1983
A 1983 rabbit-ear study from Revlon’s research lab. It tested about 30 ingredients, mostly undiluted.
Rabbit-ear test
A rabbit’s inner ear forms clogged pores within two weeks, so many ingredients could be compared quickly. Its skin reacts more than ours, so the test tends to overstate the risk.
The 0 to 5 scale
Fulton’s score for how many clogged pores an ingredient caused in the test: 0 is none, 5 is a lot. On this site, 3 and up “may clog pores” and 2 is “rated low”.
Tested at 10%
Fulton tested most ingredients at the same strength, 10%, so the results could be compared. A real product can hold more or less.
Propylene glycol
A clear liquid that Fulton mixed most ingredients into before testing.
Depends on the supplier
Fulton starred results that changed with the company that supplied the raw ingredient. Two jojoba oils can differ.
Abstract only
An abstract is the short summary at the start of a paper. When we’ve read only that, we use the paper to explain things, never for a rating.
INCI name
The official ingredient name printed on labels. Plant ingredients use their Latin name, like Simmondsia Chinensis for jojoba.