What Makes a Pore-Clogging Ingredient Pore-Clogging?

Here's the thing most people get wrong: a pore-clogging ingredient doesn't actually plug your pore. It convinces your pore to plug itself.

Certain ingredients irritate the lining of the follicle just enough that it starts overproducing skin cells. Those cells build up, form a plug, and trap oil behind it. Nothing got stuck – your skin built the blockage itself, in response to something you put on it.

The process can take months, which is why the product that broke you out might be one you started back in the spring, and why you can use something for weeks and swear it's fine.

That delay is exactly why this went unnoticed for so long. Hair pomades had been on the market for decades before anyone connected them, in the mid-1940s, to the crops of tiny whiteheads appearing along people's hairlines. The products weren't new. The link was.

Dr. James Fulton, co-inventor of Retin-A and founder of Vivant Skincare, was one of the dermatologists who chased that thread. He spent years taking cosmetics apart and testing the ingredients one at a time, and published the results in 1989. Nearly every pore-clogging list you'll find online traces back to that work.

Offenders fall into a handful of categories; we’ll cover four in this blog and a few more in an upcoming one. Here's what each one does in your products and which ones are worth avoiding.

Oils and butters

What they do: Soften skin, seal in moisture, and carry other ingredients. They're the backbone of anything rich or nourishing.

The ones that provoke a reaction: coconut oil, avocado oil, soybean oil, wheat germ oil, apricot kernel oil, evening primrose oil, hydrogenated vegetable oil. Butters too – cocoa, coconut, shea, and mango seed.

The tricky part is that oils don’t always announce themselves. They hide near the bottom of ingredient lists in products that don't feel oily at all, which means that a product can feel light and still be built on a base your pores object to.

Fatty acids

What they do: They're part of your skin's own barrier, and the right ones genuinely help rebuild it.

The main one to avoid: lauric acid.

If lauric acid sounds unfamiliar, you've still met it – it's the main fatty acid in coconut oil. Same ingredient, different name on the label, and it shows up in plenty of products that never mention coconut anywhere.

Fatty esters

What they do: Slip. Esters are why a serum sinks in instead of sitting on top, why a sunscreen spreads evenly, why a foundation glides. That silky, fast-absorbing feel is almost always an ester.

The ones to avoid: myristyl myristate, isopropyl myristate, isopropyl palmitate, isopropyl isostearate, ethylhexyl palmitate, octyl stearate, octyl palmitate, butyl stearate, decyl oleate.

Isopropyl myristate is one of the worst offenders Dr. Fulton tested, and the whole isopropyl family behaves similarly. Look for these in sunscreens, moisturizers, foundations, and primers – anything marketed as lightweight.
Fatty alcohols

What they do: Despite the name, they're not drying at all – they thicken and emulsify. They keep a lotion from separating and give a cream its body.

The ones to avoid: myristyl alcohol, isocetyl alcohol, oleyl alcohol, cetearyl alcohol + ceteareth 20.

The ones that are fine: cetyl, cetearyl, and stearyl alcohol are in nearly everything, and they're generally safe for acne-prone skin. Don't panic when you see them.

So what do you actually do with this?

Notice that every category above has a legitimate job. Oils seal in moisture. Fatty acids rebuild your barrier. Esters make products feel good enough that you'll actually use them. Fatty alcohols hold formulas together. None of this is a list of villains – it's a list of ingredients doing useful work that happens to provoke a reaction in acne-prone follicles.

Which is also why this isn't simple. These are among the most common ingredients in skincare and makeup, and the specific offenders are only a handful within much larger families. You can't avoid esters. You can avoid isopropyl myristate.

The good news is that a handful is a manageable number – and we've already done the counting. Nearly everything we carry is chosen with acne-prone skin in mind and noted on our shopping site, so there's no ingredient deck to decode and no guessing. And when it comes to makeup, we've reviewed 50 brands so far and built the guides so you don't have to squint at the back of a compact in the Sephora aisle.

Source: Fulton, J.E. "Comedogenicity and irritancy of commonly used ingredients in skin care products." Journal of the Society of Cosmetic Chemists, vol. 40, 1989, pp. 321–333