Pore-clogging ingredients are substances in skincare, makeup, and hair products that can block hair follicles, trap oil and dead skin cells inside, and trigger breakouts. They’re rated on a comedogenic scale from 0 (won’t clog pores) to 5 (highly likely to clog pores), though how much an ingredient actually affects your skin depends on its concentration, what it’s mixed with, and your individual skin type.
How Ingredients Actually Clog Pores
A clogged pore starts when something disrupts the normal shedding of skin cells inside a hair follicle. Normally, dead cells slough off and get carried out by your skin’s natural oil. When a comedogenic ingredient sits on the skin, it can trigger the cells lining the follicle to multiply faster than they can shed. These excess cells pile up, mix with oil, and form a plug. That plug is a microcomedone, the invisible precursor to every whitehead, blackhead, and inflammatory pimple.
The biological trigger involves certain fatty acids. Oleic acid, a common fatty acid in many oils and emollients, can disrupt the skin barrier at the follicle level, raising calcium levels inside skin cells. That calcium spike prompts the cells to release inflammatory signals that accelerate cell turnover even further. Palmitic acid, another fatty acid found in many cosmetic ingredients, activates a separate inflammatory pathway that also drives skin cells to over-proliferate. The end result is the same: a follicle that can’t clear itself fast enough, leading to a blocked pore.
The Comedogenic Scale
Researchers originally tested ingredients by applying them in pure form to rabbit ears, which are more sensitive than human skin. That’s important context: a substance that scores a 2 or 3 on the rabbit model may not cause problems for most people in a real-world product. The scale still provides a useful framework, though.
- 0: Non-comedogenic. No tendency to clog pores.
- 1: Slightly comedogenic. Very low risk for most skin types.
- 2-3: Moderately comedogenic. May cause issues for acne-prone skin.
- 4-5: Highly comedogenic. Significant potential to block pores, especially on the face.
Anything rated 0 or 1 is generally considered safe for breakout-prone skin. Ingredients at 4 or 5 are worth avoiding if you’re acne-prone, particularly in leave-on products like moisturizers, primers, and sunscreens that stay on your skin for hours.
Ingredients With the Highest Ratings
Several ingredients consistently score 4 or 5 and appear frequently in skincare, makeup, and body products. These are the ones most worth scanning ingredient lists for:
- Isopropyl myristate (5): A synthetic oil used to make products feel silky and absorb quickly. One of the most comedogenic ingredients tested. Common in foundations, lotions, and anti-chafing products.
- Laureth-4 (5): An emulsifier that helps oil and water mix. Found in cleansers and creams.
- Myristyl myristate (5): A waxy ester used as a skin-conditioning agent and thickener.
- Oleth-3 (5): An emulsifier derived from oleyl alcohol. Often found in creams and lotions.
- Coconut oil (4): Popular in natural skincare, but its high concentration of oleic and lauric acids gives it a rating that makes it risky for facial use on breakout-prone skin.
- Ethylhexyl palmitate (4): A lightweight emollient used as a substitute for heavier oils. Common in sunscreens and foundations.
- Isopropyl isostearate (4-5): A binding and moisturizing agent found in lip products and creams.
- Isopropyl linoleate (4-5): An emollient and skin-conditioning agent.
- Acetylated lanolin alcohol (4-5): A modified form of lanolin that enhances moisture retention but is highly comedogenic.
- Cetearyl alcohol + ceteareth-20 (4): A common emulsifying combination in lotions and conditioners.
Other notable ingredients at a 4 include polyglyceryl-3-diisostearate, steareth-10, myristyl lactate, and PEG-16 lanolin. Wheat germ oil also scores a 5.
Why Oleic vs. Linoleic Acid Matters for Oils
If you use facial oils, the single most useful thing to know is the ratio of oleic acid to linoleic acid. Oleic acid is deeply hydrating but tends to be comedogenic. Linoleic acid is lighter, helps regulate oil production, and is better suited to oily and acne-prone skin.
Oils high in oleic acid include coconut oil, cocoa butter, olive oil, and avocado oil. These work well for dry skin on the body but are risky choices for faces that break out easily. Oils high in linoleic acid include grapeseed oil, rosehip oil, evening primrose oil, and hemp seed oil. These tend to score lower on the comedogenic scale and are better tolerated by acne-prone skin. Jojoba oil is a useful middle ground. It’s technically a wax ester that closely mimics human sebum, and it scores a 2.
Stearic acid, a saturated fatty acid found in cocoa butter and shea butter, is also worth watching. It has rich, hydrating properties but is occlusive enough to clog pores in people who are sensitive to it.
Concentration and Formulation Change Everything
Here’s the catch with comedogenic ratings: they were established by testing ingredients at 100% concentration on animal skin. A finished product that contains 2% of a comedogenic ingredient behaves very differently from the pure substance. The mixture of ingredients, their concentrations, and the way they interact on human skin all alter the final comedogenic potential of a product.
This means a moisturizer containing a small amount of coconut oil-derived emollient isn’t automatically going to break you out, even though pure coconut oil rates a 4. It also means a product can contain several moderately comedogenic ingredients at low concentrations and still cause problems through their combined effect. There’s no simple formula for predicting this, which is why patch-testing matters more than ingredient-list analysis alone.
Silicones and Petrolatum: Not as Bad as Reputation Suggests
Silicones (dimethicone, cyclomethicone, cyclopentasiloxane) rate a 1 on the comedogenic scale and have been a target of consumer backlash that outpaces the science. Clinical testing shows silicone-based emulsions are non-irritating, non-comedogenic, and, contrary to popular belief, not truly occlusive. In controlled studies comparing silicone-containing creams to a saline control, the silicone products did not trap moisture any differently than the control, meaning they weren’t sealing the skin shut. Petroleum jelly, on the other hand, is genuinely occlusive and was used as the positive control for occlusion in those same tests.
That said, silicones can still contribute to breakouts in specific situations. If you layer a silicone-heavy primer under heavy makeup without cleansing thoroughly, the silicone can trap sweat, bacteria, or other comedogenic ingredients against your skin. The silicone itself isn’t clogging your pores, but it may be holding something else in place that does.
Hair Products Are an Overlooked Source
If you get small whiteheads or flesh-colored bumps along your hairline, forehead, or the back of your neck, your hair products are a likely cause. Shampoos, conditioners, styling gels, waxes, and pomades frequently contain oils that migrate onto skin. Once there, they clog pores just like any leave-on facial product would.
Pomades and heavy styling products are the most common culprits, but even shaving creams and aftershaves can contain comedogenic oils. The American Academy of Dermatology recommends looking for products labeled “oil free,” “non-comedogenic,” or “won’t clog pores” if you notice breakouts in these areas. Rinsing your face and neck after conditioning your hair can also help, since conditioner residue running down your skin during a shower is a surprisingly common trigger.
“Non-Comedogenic” Labels Aren’t Regulated
The term “non-comedogenic” on a product label has no legal definition and no standardized testing requirement behind it. The FDA requires that cosmetic labeling not be false or misleading, and products that violate labeling rules can face regulatory action. But there is no specific FDA standard a product must meet before printing “non-comedogenic” on the package. A brand can use the term based on its own internal testing, third-party testing, or simply because the formula avoids known comedogenic ingredients.
This doesn’t mean the label is useless. Many reputable brands do test their products. But it does mean you can’t treat “non-comedogenic” as a guarantee. If your skin is highly reactive, checking the actual ingredient list against known comedogenic ingredients is more reliable than trusting front-of-package claims. Several free online databases let you paste in a full ingredient list and flag anything with a high comedogenic rating, which takes the guesswork out of the process.