Comedogenic ingredients are substances in skincare and cosmetic products that can clog your pores and lead to blackheads, whiteheads, or acne breakouts. They’re rated on a scale from 0 to 5, where 0 means no risk of clogging pores and 5 means highly likely to cause blockages. As a general rule, ingredients rated 2 or below are considered safe for most skin types, while anything rated 4 or 5 is a significant concern, especially if you’re acne-prone.
How the Comedogenic Scale Works
The comedogenic scale assigns every tested ingredient a number from 0 to 5 based on its likelihood of blocking pores:
- 0: Non-comedogenic, will not clog pores
- 1: Slightly comedogenic, very low risk
- 2–3: Moderately comedogenic
- 4–5: Highly comedogenic, strong likelihood of clogging pores
These ratings were originally developed using the rabbit ear assay, a lab test that applied concentrated ingredients to the inner ears of rabbits and measured the resulting pore blockage. The rabbit model turned out to be more sensitive than human skin, meaning some ingredients that scored as mildly comedogenic in rabbits are probably safe for most people. Later testing on human subjects confirmed that ingredients scoring moderately to highly comedogenic in the rabbit model do genuinely cause clogged pores in people, though weakly comedogenic substances are likely safe for anyone except those who are already acne-prone.
One important caveat: the FDA does not regulate or define the term “non-comedogenic.” There is no approved standard or required test a product must pass before using that label. It’s essentially a marketing claim, which means reading the actual ingredient list matters more than trusting front-of-package language.
How These Ingredients Actually Clog Pores
Comedogenic ingredients trigger a process called hyperkeratinization inside hair follicles. Normally, dead skin cells lining the inside of a pore shed and get pushed out. Comedogenic substances disrupt this process, causing those cells to stick together and build up instead. The result is either a partial blockage (an open comedone, or blackhead) or a complete blockage (a closed comedone, or whitehead) that traps oil underneath.
The exact mechanism varies by ingredient. Some, like isopropyl myristate, are structurally similar to the natural oils your skin produces. Because of that similarity, your follicles absorb them readily rather than keeping them on the surface. Once inside the pore, these compounds mix with sebum, alter its composition, and promote the formation of microcomedones, the invisible precursors to visible breakouts. Isopropyl myristate is also resistant to water-based cleansers, so it can accumulate in pores over time with repeated use.
High-Risk Ingredients to Watch For
Ingredients rated 4 or 5 are the most likely to cause problems. Here are the most common ones you’ll encounter on product labels:
- Isopropyl myristate (5): A synthetic ester used to make products feel silky and absorb quickly. One of the most consistently flagged ingredients in comedogenicity testing.
- Myristyl myristate (5): Another derivative of myristic acid, used as a skin-conditioning agent and emollient.
- Laureth-4 (5): A surfactant and emulsifier found in cleansers and moisturizers.
- Oleth-3 (5): An emulsifying agent derived from oleyl alcohol.
- Cetyl acetate (4–5): Used as a skin-conditioning agent in creams and lotions.
- Isopropyl isostearate (4–5): A binding and texturizing agent in foundations and moisturizers.
- Isopropyl linoleate (4–5): An emollient found in various skincare and hair products.
- Acetylated lanolin alcohol (4–5): A modified form of lanolin used for its moisturizing properties.
- Coconut oil/butter (4): A popular natural ingredient that scores high due to its lauric acid content.
- Cocoa butter (4): Rich and occlusive, commonly found in body lotions and lip products.
- Ethylhexyl palmitate (4): A lightweight emollient used as a substitute for heavier oils.
- Isopropyl palmitate (4): Similar to isopropyl myristate in structure and risk level.
- Lanolin (4): A waxy substance derived from sheep’s wool, found in lip balms and heavy moisturizers.
- Lauric acid (4): A fatty acid abundant in coconut oil.
- Oleyl alcohol (4): A fatty alcohol used as an emollient and thickener.
- Steareth-10 (4): An emulsifier commonly used in lotions.
A practical rule: if a highly rated ingredient appears near the top of a product’s ingredient list, that product contains a significant amount of it. Ingredients listed further down are present in smaller concentrations and pose less risk.
Why Certain Esters and Fatty Acids Are the Worst Offenders
You’ll notice that many of the highest-rated ingredients are synthetic esters, compounds formed by combining a fatty acid with an alcohol. Isopropyl myristate, isopropyl palmitate, and isopropyl isostearate all follow this pattern. These esters are popular in cosmetic formulation because they spread easily, help other ingredients penetrate the skin, and give products a lightweight, non-greasy feel.
The problem is that their penetration-enhancing properties work on pores just as effectively as they work on the skin’s surface. Their small molecular weight lets them migrate deep into follicular canals, where they accumulate. Because their chemical structure mimics the fatty acids in your own sebum, follicles absorb them without resistance. Dermatologists frequently observe an increase in closed comedones (whiteheads) in patients using products high in these esters.
Not all compounds sharing a name carry the same risk. “Myristate,” for example, just refers to any derivative of myristic acid. Isopropyl myristate scores 4–5, myristyl myristate scores 5, but glyceryl myristate sits around 3. The specific alcohol or molecule paired with the fatty acid changes the comedogenic potential significantly.
How Popular Skincare Oils Compare
Natural oils vary enormously in their comedogenic ratings, so lumping all facial oils together as pore-clogging isn’t accurate. Here’s how some of the most commonly used carrier oils stack up:
- Argan oil (rating: 0): Non-comedogenic, suitable for all skin types including acne-prone.
- Rosehip oil (rating: 1): Very low risk. Works well for dry, combination, and acne-prone skin, particularly for scarring.
- Jojoba oil (rating: 2): Moderately low risk. Its structure closely mimics human sebum, which can actually help regulate oil production in acne-prone skin.
- Coconut oil (rating: 4): High risk for facial use. Better suited for body care or hair treatments.
Coconut oil is one of the most searched ingredients in this category, and its high rating comes largely from lauric acid (rated 4 on its own). Despite its popularity in natural skincare, it’s one of the worst choices for anyone prone to facial breakouts.
Why Ratings Don’t Tell the Whole Story
The comedogenic scale is a useful starting point, but it has real limitations. The original ratings come from testing pure, concentrated ingredients applied directly to skin, often in rabbit models that are more reactive than human skin. In a finished product, an ingredient rated 4 might be present at 1% concentration, blended with other compounds that change how it interacts with your pores.
Your individual skin also matters enormously. Someone with naturally low sebum production and large pores may tolerate a moderately comedogenic ingredient with no issues, while someone with oily, acne-prone skin might break out from the same product. Factors like how long a product stays on your skin (a cleanser washes off in seconds, while a moisturizer sits for hours), the climate you live in, and the rest of your routine all influence whether a particular ingredient causes problems for you.
The most practical approach is to use the scale as a filter, not a verdict. If you’re prone to clogged pores, avoid products where ingredients rated 4 or 5 appear in the first several positions on the label. For ingredients in the 2–3 range, your own skin’s response is a better guide than any chart.