From skincare adverts to beauty content, the term comedogenicity gets throw around a lot. Even worse there’s a lot of mixed messaging around the meaning of comedogenicity and usefulness. There are as many people who religiously advocate for it as there are those who dismiss it as marketing. In this article we explore what comedogenicity really means. We’ll also review how the scale works and what it can tell us about pore-clogging ingredients. We’ll also review how useful it is and share our top tips for making smarter skincare choices.
What is Comedogenicity?
In the context of skincare and cosmetics, the meaning of comedogenicity is the likelihood an ingredient will clog pores. This then causes blackheads and whiteheads. It is worth noting that this is completely distinct from purging. In general purging occurs when certain actives speed up skin turnover to cause temporary breakouts. The concept of comedogenicity gained steam in the 1970s when researchers noticed that certain cosmetic ingredients were worsening acne symptoms in some people.
The early studies tested ingredients on animals like rabbits and found that certain substances quickly blocked pores. These findings formed the foundation of what we now understand about comedogenicity. However, alongside ethical concerns scientists also quickly realised that animal testing didn’t always translate to human skin. In the 1980s, researchers began conducting more relevant tests on human volunteers. Studies usually involved applying substances to the skin on the backs of test subjects to see if they blocked pores. This allowed them to develop a general meaning of comedogenicity in humans as well as build up a database of ingredients categorised by their likelihood to cause pores.
The Comedogenic Scale
To help consumers and doctors better understand the pore-clogging potential of ingredients, researchers developed a comedogenicity rating system. This scale assigns numerical values to ingredients based on how likely they are to block pores and trigger blemishes. It’s a popular tool for guiding product selection, especially for those with acne-prone or oily skin. Most comedogenic charts rate ingredients on a scale of 0 to 5 although some range only from 0 to 3. Regardless, the message is the same with higher scores meaning greater risk of comedogenicity. Below is the a typical comedogenic scale:
- 0 = non-comedogenic (won’t clog pores)
- 1–2 = low potential
- 3–5 = increasing potential to cause blemishes
One thing to note is that common skincare ingredients vary widely in their comedogenic ratings. For instance, coconut oil and cocoa butter are often rated 3–5 on the comedogenicity scale meaning they’re more likely to clog pores especially for acne-prone skin. Ingredients like oleic acid and lanolin usually also fall within the same high-risk range. On the other end of the spectrum, jojoba oil, hemp seed oil, glycerin and hyaluronic acid typically score between 0–2. This means a lower likelihood of blocking pores and that they may be more suitable for reactive or breakout-prone skin. As a general rule, people with oily or acne-prone skin should lean towards skincare products rated 0–2 on the comedogenic scale. If you have previously had breakouts and congestion from specific products, identify the problematic ingredients in them then use the comedogenic scale to help you avoid similar ones.
Limitations of the Comedogenic Scale
Although the comedogenic scale can be a useful starting point, it’s far from perfect. The comedogenicity rating system is built on data compiled from a mix of lab tests, animal studies and human trials. The tests also don’t always reflect how these ingredients behave when used in skincare products on human skin. Below are some of the key limitations to be aware of:
- Test Methods Don’t Reflect Real Usage: Obviously data from animal and cell culture studies cannot accurately represent what happens in human skin. Even the human back tests differ from facial skin so there’s a limit to how much you can extrapolate this data to real life usage.
- Concentration Matters: An ingredient may be comedogenic at 100% but when you use it at say 2–10% in a formula it might not clog pores. For instance, acetylated lanolin alcohol scores 4–5 when it is pure however may drop to 1 at low percentages.
- Formulation Matters: A product is more than just its individual actives. Emulsifiers, pH levels, textures and ingredient interactions all influence pore-clogging risk.
- Individual Skin Variation: Your skin’s response is unique. Genetic factors, oil composition and sensitivity all affect whether an ingredient might be problematic for you.
- No Legal Definition: Neither UK nor US regulators define “non-comedogenic” formally. Brands may label products but without standardised testing which often makes the term more marketing than medical.
How to Keep Your Pores Clear
Knowing which ingredients may carry a higher risk of clogging pores is useful but it is only part of the picture. To truly reduce your chances of breakouts, it’s important to build habits that support your skin’s health and personalise your skincare routine to your needs. Here are some of our top tips to help you make smarter skincare choices:
- Scrutinise Ingredient Lists: Look at the first six to eight ingredients as these dominate the formula in terms of concentration. Make sure that none of these have high comedogenicity or ingredients you have previously had problems with.
- Patch-Test Every New Product: Apply product behind your ear or on your jawline for 48 hours to check for irritation or breakouts.
- Introduce One Product At A Time: That way if your skin reacts, you’ll know exactly what’s causing this. You can then not only avoid this ingredient but identify others with similar comedogenicity or sensitivity profiles.
- Use Ingredient Lookup Tools: Use reputable websites and apps that provide comedogenic rating lists for guidance.
- Choose the Right Actives: If you have acne-prone skin, it’s especially important to include ingredients that control oil and keep pores clear. Exfoliating acids like Salicylic acid and other BHAs help to clear dead skin and prevent pore congestion. Meanwhile, benzoyl peroxide and retinoids like Tretinoin and Adapalene can tackle and prevent acne. For hydration, ingredients such as hyaluronic acid and glycerin provide moisture without clogging pores whilst Zinc PCA can help control oil production.
- Seek Help: If you’re really struggling, connect with a dermatologist or healthcare provider. They can help you put together a skincare program to target your skin concerns without triggering breakouts or irritation.
First of all, comedogenicity is not a concern for everyone and depends on your skin type and whether you have any dermatological problems. It is usually more useful to think about how your skin has in the past responded to different ingredients as this will help you identify problematic ones for your skin. Comedogenicity is however a useful guide even if it is not an exact science. The ingredient ratings can offer helpful direction, as long as you also take into account factors like ingredient concentration, formulations and your individual skin responses. With a little patience and a methodical approach, you can build a routine that works with your skin.
At City Skin Clinic, we are super passionate about personalised skincare. Through our online skin clinic, our doctors offer safe and effective treatments using ingredients like Tretinoin, Spironolactone, Azelaic acid and Hydroquinone where appropriate. We treat a range of skin conditions including acne, hyperpigmentation, melasma and skin ageing. To start your personalised skincare plan, book a virtual video consultation or use our online consultation form. The journey towards great skin starts here.
