Is isopropyl myristate comedogenic? Rated 5 on published lists

Isopropyl myristate is the isopropyl ester of myristic acid, a 14-carbon fatty acid, and it carries a rating of 5 on the pore-clogging list published on this site — the top of the 0-5 scale. It is one of 17 entries at that rating among 86, and one of the names that turns up most often in a real routine.

This page covers the chemistry behind the name, the job a formulator hires it to do, the product categories where it appears, what a 5 is and is not recording, why it is flagged under this site’s Malassezia rule as well, and when the number is not worth acting on.

What isopropyl myristate is

Isopropyl myristate is an ester: myristic acid, a saturated 14-carbon fatty acid, joined to isopropyl alcohol. The result is a clear, thin, nearly odourless liquid with a molecular weight around 270 — light enough to spread very fast, and non-volatile, so it stays on the surface without feeling as though it does.

The label family around it matters more than the single name, because the entries share a mechanism and mostly share a rating. Reformulating away from one ester frequently lands on its neighbour, and the neighbour is often on the same list.

Four isopropyl esters sit on the 86-entry reference, and three of them carry a 5. That clustering is a property of the assay these ratings came from, which reacted strongly to short, fast-spreading esters as a class, rather than a finding about isopropyl myristate on its own.

Why a formulator reaches for it

A formulator uses isopropyl myristate to take greasiness out of a texture. It spreads a product quickly into a very thin layer, leaves a dry finish instead of an oily one, dissolves pigments and solid UV filters, and costs a fraction of the speciality esters that could replace it. Its ubiquity follows from that combination.

That last point is the one usually missing from the discussion. Isodecyl oleate is rated 4 on the same reference, octyl stearate is rated 5, and a brand that removes one ester to satisfy a pore-clogging list often reaches for a chemical cousin that a different list flags just as hard.

Where isopropyl myristate turns up on a label

Isopropyl myristate appears wherever a formula needs to feel light and still carry oil-soluble material. Cleansing balms, colour cosmetics, sunscreens, body lotions, hair conditioners and aerosol products all use it for the same two properties, which is why it shows up across categories that otherwise have nothing in common.

Position carries real information up to a point. Ingredient lists run in descending proportion down to one per cent, after which the order means nothing, so the same ester listed third and listed twenty-fourth describe two very different formulas that a rating table cannot tell apart.

What a rating of 5 is recording

A rating of 5 places isopropyl myristate at the ceiling of the 0-5 comedogenic scale, alongside 16 other entries out of the 86 published here. The score came from a screening assay on rabbit ear tissue, applied to the material at or near full strength — not to a finished product on human facial skin.

No regulator stands behind any of this. There is no FDA, EU or global organisation that certifies or regulates comedogenic ingredient lists, every circulating table is a private compilation with an author and a cut-off date, and two careful lists routinely disagree about the same ester with no authority to appeal to. How the 0-5 ratings were produced sets out the assay and its lineage.

A 5 describes a material tested nearly neat on tissue chosen for how readily it reacts. The proportion of that material in the bottle on your shelf is the variable the assay never measured.

The honest summary is narrow. Isopropyl myristate is a member of a published set, that membership is checkable in a minute against the list printed on this site, and everything beyond membership — concentration, the rest of the formula, your skin — sits outside what the number can address.

Isopropyl myristate and fungal acne

Isopropyl myristate is flagged under the Malassezia rule this site publishes as well. The yeasts associated with fungal acne take up fatty acids of roughly C11 to C24; myristic acid is C14; binding it to isopropyl alcohol leaves that chain intact, so the ester matches the rule rather than escaping it.

That overlap is worth reading carefully, because it is not total. Potassium chloride and sodium chloride are rated 5 and match nothing in the Malassezia rule, while silicones such as dimethicone are absent from the pore-clogging list and sit on the Malassezia exception list too. Isopropyl myristate happens to fall inside both, which is why it surfaces in two separate searches people run for different reasons.

If the concern is small uniform bumps rather than blackheads and closed comedones, the fungal acne safe checker applies the chain-length rule and prints it in full on the same page. Folliculitis is a clinical diagnosis; no ingredient list makes one.

What to do when it is on a label you already own

Finding isopropyl myristate on a label is a starting point for a test, not a reason to bin a product. The useful next step is to read the whole ingredient list, note where the ester sits, and change one variable at a time — because a routine that changes in three places at once produces a result you cannot attribute to anything.

1. Step 1

   Read the full list, not the first line

   Note how far down the ester sits. High on a short label and last on a label of thirty names are different situations, and no rating table distinguishes them.

2. Step 2

   Check one product at a time

   Pasting two ingredient lists together merges the counts and destroys the ordering, which is the only proportion signal a label gives you.

3. Step 3

   Remove one thing, then wait

   A comedo takes weeks to form and weeks to clear, so a fair trial runs four to eight weeks. Dropping three products in one week answers nothing.

4. Step 4

   Check whatever replaces it

   Substitutes are frequently other esters from the same family. Run the replacement product through the same list before assuming the swap changed anything.

The pore-clogging ingredients checker runs that match in your browser against the same 86-entry reference, prints the rating beside each hit rather than averaging everything into one score, and reports how many names it could not read instead of calling a product clean.

Where this check is the wrong tool

A membership check answers one question: is this name on this list. It cannot say what a finished product will do on a particular face, and anyone who has decided that a rating of 5 settles the matter is asking a list to do work it was never built for.

Nothing on this page is medical advice, and no page on this site publishes a verdict on any named brand’s product. The rest of the skincare ingredient hub follows the same rule: what the published lists contain, what they omit, and where the evidence stops.