Fundamentals

Comedogenic Ingredients: The Complete Guide to Pore-Clogging Ratings

Learn what comedogenic means, how the 0-5 pore-clogging rating scale works, which ingredients to watch for, and why these ratings aren't the full story.

Comedogenic Ingredients: The Complete Guide to Pore-Clogging Ratings

In 1972, dermatologists Albert Kligman and Otto Mills identified a pattern of persistent, low-grade acne caused by cosmetic products — coining the term "acne cosmetica" in their landmark Archives of Dermatology study. Over 50 years later, the FDA still does not regulate or define the term "non-comedogenic," leaving consumers to navigate ingredient lists on their own. Here's how to actually read comedogenic ratings and what they mean for your skin.

Quick Summary:

  • Comedogenic ratings rank ingredients from 0 (won't clog pores) to 5 (highly likely to clog pores) based on lab testing
  • Isopropyl myristate (rated 5), coconut oil (rated 4), and cocoa butter (rated 4) are among the most common pore-clogging ingredients
  • The original ratings came from rabbit ear testing in the 1970s-80s and don't always translate to human skin
  • "Non-comedogenic" on a product label has no regulated definition — brands self-assign it without standardized testing
  • A product's full formulation matters more than any single ingredient's comedogenic rating

What Does Comedogenic Mean?

Comedogenic describes any substance that tends to cause comedones — clogged pores that show up as blackheads and whiteheads. The term comes from "comedo," the dermatological name for a plugged hair follicle.

After Kligman and Mills published their 1972 paper, researchers developed the rabbit ear assay: scientists applied individual ingredients to rabbit ears (which have large, sensitive follicles) and measured follicular plugging over 2-4 weeks. The results were graded on a 0-5 scale, creating the comedogenic rating system still referenced today.

The 1984 study by Fulton, Pay, and Fulton in the Journal of the American Academy of Dermatology tested hundreds of ingredients and finished products using this method. Their results form the backbone of most comedogenic ingredient lists you'll find online.

The Comedogenic Rating Scale

The 0-5 scale works like this:

  • 0 — Non-comedogenic: No pore-clogging potential. Examples: mineral oil (purified), hyaluronic acid, glycerin
  • 1 — Slightly comedogenic: Very low risk. Examples: beeswax, shea butter, castor oil
  • 2 — Moderately low: Some individuals may react. Examples: stearic acid, lanolin (varies by source), jojoba oil
  • 3 — Moderate: Noticeable pore-clogging potential. Examples: cottonseed oil, mink oil, soybean oil
  • 4 — Fairly high: Likely to cause breakouts for acne-prone skin. Examples: coconut oil, cocoa butter, flaxseed oil
  • 5 — Highly comedogenic: Strong likelihood of clogging pores. Examples: isopropyl myristate, wheat germ oil, isopropyl palmitate

The American Academy of Dermatology endorsed this grading system in 1989, advising that ingredients scoring 0-1 could be considered safe for acne-prone individuals.

Comedogenic rating scale reference chart

Common Comedogenic Ingredients to Watch For

These ingredients consistently score 3 or higher across studies:

Rating 5 (highest risk):

  • Isopropyl myristate — found in many lotions and makeup
  • Isopropyl palmitate — common in moisturizers and foundations
  • Wheat germ oil — sometimes in "natural" skincare products

Rating 4:

  • Coconut oil — popular in DIY skincare but a known pore-clogger
  • Cocoa butter — common in body lotions, risky for facial use
  • Acetylated lanolin alcohol — found in some creams and lipsticks
  • Flaxseed oil — marketed as healthy but problematic on acne-prone skin

Rating 3:

  • Cottonseed oil — used in some emollients
  • Soybean oil — appears in various facial products
  • Myristic acid — found in some cleansers and creams

If you're prone to breakouts, scan ingredient labels for these compounds, particularly in leave-on products like moisturizers and primers where ingredients sit on skin for hours.

Non-Comedogenic Ingredients That Are Generally Safe

These ingredients rate 0-1 and work well for acne-prone skin:

  • Dimethicone (silicone, rated 0-1) — creates a breathable barrier without plugging follicles
  • Hyaluronic acid (rated 0) — hydrates by drawing water to skin, no pore-clogging risk
  • Niacinamide (rated 0) — reduces sebum production and helps minimize pore appearance
  • Glycerin (rated 0) — lightweight humectant safe for all skin types
  • Squalane (rated 0-1) — mimics skin's natural oils without comedogenic effects
  • Argan oil (rated 0) — one of the few facial oils safe for breakout-prone skin
  • Salicylic acid (rated 0) — actually helps clear existing comedones

Non-comedogenic ingredient examples

Why Comedogenic Ratings Aren't the Full Story

Here's where it gets complicated. A 2006 study by Draelos and DiNardo in the Journal of the American Academy of Dermatology delivered a critical finding: "Finished products using comedogenic ingredients are not necessarily comedogenic." The researchers tested complete formulations on human volunteers and found that a product's overall chemistry matters far more than any single ingredient.

Several factors limit the original ratings:

The rabbit ear problem. Most ratings come from rabbit ear assays conducted in the 1970s-80s. Rabbit ear follicles are far more sensitive than human pores. Kligman and Mills themselves found in their 1982 human follow-up that some ingredients rated highly comedogenic in rabbits produced minimal breakout response on human skin.

Concentration matters. A comedogenic ingredient at 0.5% of a formula behaves differently than the same ingredient at 30%. The original tests applied pure ingredients — not the diluted amounts in most skincare products.

Formulation chemistry. How ingredients interact changes their behavior. An emulsifier might reduce a comedogenic oil's occlusive properties. The whole product is not the sum of its individual ratings.

Individual variation. Two people with acne-prone skin can react completely differently to the same ingredient. Genetics, pore size, and sebum composition all play a role.

Verdict: Comedogenic ratings are a useful starting point — not a verdict. Use the 0-5 scale to flag potential problem ingredients, especially at ratings of 3 and above, but test products on your own skin rather than rejecting anything based on a single ingredient's score.

How to Check If Your Products Are Comedogenic

You don't need to memorize the entire comedogenic rating list. These practical tools do the work:

Online ingredient analyzers: Websites like INCIDecoder and CosDNA let you paste a full ingredient list and flag potentially comedogenic compounds with their ratings.

The label test. Flip the product over and check the first 5-6 ingredients (the highest concentration). Cross-reference unfamiliar names against a comedogenic ingredient database.

The patch test. Apply a small amount to your jawline nightly for 2 weeks. New closed comedones (small, skin-colored bumps) in the test area suggest the product doesn't work for your skin.

Track your products. If breakouts appear 2-4 weeks after starting a new product, that timeline matches comedogenic acne. Stop the product and see if skin clears within 4-6 weeks.

Recommended Non-Comedogenic Products

These products are formulated without high-rated comedogenic ingredients and work well for breakout-prone skin:

CeraVe Foaming Facial Cleanser (around $16) removes excess oil without stripping the skin barrier, using ceramides and niacinamide that rate 0 on the comedogenic scale.

Neutrogena Hydro Boost Water Gel (around $20) delivers oil-free hydration through hyaluronic acid — completely non-comedogenic and lightweight enough for oily skin.

The Ordinary Niacinamide 10% + Zinc 1% (around $12) targets sebum production and congestion with two ingredients that have zero comedogenic potential.

EltaMD UV Clear SPF 46 (around $39) is one of the few sunscreens specifically formulated for acne-prone skin, with niacinamide and zinc oxide instead of pore-clogging emollients.

Paula's Choice Skin Perfecting 2% BHA Liquid Exfoliant (around $34) actively dissolves the buildup inside pores, treating existing comedones while preventing new ones.

Vanicream Moisturizing Skin Cream (around $15) skips common comedogenic triggers like lanolin, fragrances, and dyes — a safe bet for sensitive, breakout-prone skin.

Common Mistakes with Comedogenic Ingredients

Avoiding all oils blindly. Not all oils clog pores. Squalane, argan oil, and rosehip seed oil rate 0-1 and can benefit acne-prone skin. "Oil-free" isn't automatically better than a product with low-comedogenic oils.

Trusting "non-comedogenic" labels at face value. The FDA does not define or regulate this term. Brands self-assign it without standardized testing. Always check the actual ingredient list.

Ignoring product type. A comedogenic ingredient in a rinse-off cleanser on skin for 30 seconds is far less concerning than the same ingredient in a night cream worn for 8 hours.

Rating-stacking paranoia. Adding up individual ingredient scores isn't how formulation chemistry works. A product with three "rating 2" ingredients doesn't equal a "rating 6" product.

Frequently Asked Questions

What does comedogenic mean?

Comedogenic means an ingredient has the potential to clog pores by causing excess keratin buildup inside hair follicles. This leads to comedones — blackheads and whiteheads — which can progress to inflammatory acne.

Is coconut oil comedogenic?

Yes. Coconut oil rates 4 out of 5 on the comedogenic scale. While some people tolerate it on their body, applying coconut oil to the face causes breakouts for most acne-prone individuals.

What does non-comedogenic mean on a product label?

In the United States, "non-comedogenic" has no legal or regulated definition. The FDA does not require specific testing before a brand prints this claim. It suggests the manufacturer believes the product won't clog pores, but there's no standardized verification behind it.

Can a product with comedogenic ingredients still be safe to use?

Yes. A 2006 JAAD study found that finished products containing known comedogenic ingredients did not always produce comedones on human skin. Concentration, formulation chemistry, and individual skin all factor in.

What is the comedogenic scale?

A 0-5 rating system developed from laboratory testing (primarily rabbit ear assays) in the 1970s-80s. It ranks ingredients by their likelihood of clogging pores, from 0 (no risk) to 5 (high probability of breakouts).

Is dimethicone (silicone) comedogenic?

Dimethicone rates 0-1 and is not pore-clogging. Despite myths about silicones "suffocating" skin, dimethicone forms a breathable barrier and is a standard ingredient in products formulated for acne-prone skin.

How do I know if a product is clogging my pores?

Comedogenic breakouts typically appear 2-6 weeks after starting a new product as clusters of small, non-inflamed bumps (closed comedones) where you applied it. If stopping the product clears the bumps within 4-6 weeks, it was the culprit.

Are natural or organic products less comedogenic?

No. Coconut oil (rated 4) and wheat germ oil (rated 5) are completely natural and highly comedogenic. Synthetic dimethicone (rated 0-1) is often safer for acne-prone skin than natural alternatives.

What oils are non-comedogenic?

Squalane (rated 0-1), argan oil (rated 0), hemp seed oil (rated 0), and rosehip seed oil (rated 1) are among the safest facial oils. They provide hydration without the pore-clogging risk of coconut or wheat germ oil.

Should I avoid all comedogenic ingredients?

Not necessarily. The ratings serve as a screening tool, not a hard rule. If a product with a moderately comedogenic ingredient (rated 2-3) works well for your skin without causing breakouts, there's no reason to stop using it. Your skin's response is the most reliable test.

The Bottom Line

Comedogenic ratings give you a practical starting point for screening skincare ingredients, but they're not absolute. The 0-5 scale, developed from rabbit ear testing decades ago, doesn't account for formulation chemistry, ingredient concentration, or individual skin differences. Use the ratings to flag high-risk ingredients — especially at level 3 and above — then patch test products on your own skin for the most reliable answer.

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