Pore-Clogging Ingredients
What comedogenic ratings mean and how to choose for acne-prone skin

What comedogenic ratings mean, from 0 to 5

Comedogenic describes how likely an ingredient is to clog pores and cause blackheads or whiteheads (comedones). The scale usually runs from 0 to 5. A 0 means no clogging has been reported, and higher numbers mean clogging is more likely.

People often read 0 to 2 as low and 3 or above as a reason for caution. That is a common habit, not an official standard, and the same ingredient can carry different ratings in different sources.

The ratings come from rabbit ear tests

In 1972, dermatology researchers Kligman and Mills proposed a way to measure how much cosmetic ingredients clog pores (Kligman and Mills, 1972). They applied undiluted ingredients to the inner ear of rabbits for several weeks, then examined how blocked the follicle openings became. Today's 0 to 5 scale is commonly traced back to this line of research.

Why not to take the rating at face value

• Rabbit ears clog far more easily than human skin. In 2006, Draelos and DiNardo pointed out that the rabbit ear model does not reliably predict how human skin reacts (Draelos and DiNardo, 2006). Clogging in a rabbit does not mean clogging on your face.
• The test used the pure ingredient. Real products contain much smaller amounts mixed with other ingredients. If an ingredient sits near the end of the list in a small amount, its undiluted rating does not translate directly. For how to read the list, see the 1% rule.
• People react differently. Oil production, pore size, barrier condition and hormones all change the outcome, so the same ingredient can trigger breakouts for one person and nothing for another. The gap is bigger for acne-prone skin.

Ingredients often named as pore-clogging

Here are ingredients that come up often in acne skin communities, split by whether they are commonly rated high or low. Given the limits above, treat them as names to double-check, not as automatic deal breakers.

• Commonly rated high: coconut oil, cocoa butter, isopropyl myristate and wheat germ oil. Isopropyl myristate is added to make textures smoother, so it shows up on labels often.
• Commonly rated low: squalane, rosehip oil and jojoba oil. Jojoba is technically a liquid wax rather than an oil. Squalane is covered in more detail in the squalane guide.

Even if coconut oil or cocoa butter is rated high, using them on lips, body or hair is a different matter from the face. Oily or acne-prone skin only needs to be careful on the face.

A non-comedogenic label is not a guarantee

"Non-comedogenic" on a label sounds reassuring. But neither Korea's MFDS nor the U.S. FDA has a process to certify it, so manufacturers can apply it at their own discretion. Some brands run their own tests first, but standards vary, so treat it as a hint.

How to choose for acne-prone skin

• Start at the top of the list. Ingredients near the top make up more of the product. If several highly rated oils sit there, acne-prone skin should think twice.
• Think about your skin type first. Oily and acne-prone skin tends to be more sensitive to highly rated oils. For dry or sensitive skin, moisture that supports the barrier matters more than the rating.
• The final check is a patch test. A rating is only an average likelihood, so your own reaction is what counts. Try a new oil or rich cream along the jaw or behind the ear for one to two weeks first. The steps are in how to patch test.

Frequently asked questions

Should I avoid every product with a high comedogenic rating ingredient?

No. The rating comes from tests with the undiluted ingredient, so a small amount mixed into a product can behave differently. Weigh how much is in the product alongside how your own skin reacts.

Can I trust a non-comedogenic label?

Do not treat it as a guarantee. Neither Korea's MFDS nor the U.S. FDA certifies the claim, so manufacturers can apply it at their own discretion. Use it as a hint and confirm with a patch test.

Should I keep coconut oil off my face?

Coconut oil is commonly rated high, so oily or acne-prone skin is better off being careful with it on the face. On dry skin, lips, body or hair it is often fine. Try it on a small area before using it on the whole face.

Can acne-prone skin use oils?

It depends on the oil. Oils rated low, such as squalane or rosehip oil, are known to be fairly well tolerated by acne-prone skin. Keep high-rated oils like coconut oil away from breakout-prone areas.