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It plays several roles in a formula:

Typical use levels for this ingredient sit around 1-10% and the Cosmetic Ingredient Review Expert Panel has affirmed safety at concentrations up to 25% in leave-on products.

Multiple assessments have found it to be non-irritating and non-sensitizing to most people.

However, there have been some cases of allergic contact dermatitis in patients with chronically compromised skin barriers.

Cetearyl alcohol has a comedogenic rating of 2 and irritancy rating of 1. Both of these numbers come from the 1989 study that used rabbit ears; a "2" means mildly comedogenic and a "1" means low irritancy.

Here's the catch: rabbit skin is more sensitive than human skin and throws a lot of false positives. A 1996 reappraisal found that ingredients rated 1-2 in the rabbit ear tests are generally safe for humans.

Remember comedogenic ratings are unable to assess the entire formula of a product or how it will react on your skin. Just be sure to patch test if you are unsure about certain ingredients.

This ingredient is not fungal acne safe. Cetearyl alcohol is a fatty alcohol with chain lengths that fall within the range that Malassezia can metabolize.

A 2019 study has also observed Malassezia growth in the presence of this ingredient, confirming it to be not-fungal acne safe.

Your skin makes glycerin on its own (mostly from sebaceous oil breakdown) and shuttles it to your outermost layer of skin, or your epidermis, via aquaporin-3.

Aquaporin-3 is a transporter that is essential for normal skin hydration, elasticity, and repair. Interestingly, mice lacking in AQP3 have dry and less elastic skin that can be fully corrected with glycerin.

This ingredient is non-irritating, plays well with almost every ingredient, and works across all skin types. Typical use is anywhere between 3-10% but can go up to 79% in some leave-on products.

Just know very high concentrations (>40%) can feel tacky in low humidity.

Glycerin is the name for this ingredient in American English. British English uses Glycerol/Glycerine.

Reported use concentrations run from 0.002%-100% and any number over 50% usually comes from a nail product.

Actual skincare numbers run much lower: cleansers (0.3-26%), toners (0.07-7%), face moisturizers (0.04-0.2%).

The Cosmetic Ingredient Review Expert Panel reviewed it and concluded it is safe in the present practices of use and the International Agency for Research on Cancer classifies it as a non-carcinogenic to humans.

True allergy to this ingredient is uncommon but real: 44 out of 1,450 patients patch tested between 1992-2011 reacted with most cases clustering in people with leg ulcers, occupational hand eczema, or repeated use of Isopropyl Alcohol on already-broken skin.

Irritation and dryness are far more likely than allergy; before you throw away your skincare, just know this is dose-dependent and the risk is modest.

The irritant potential of the alcohols used in hand antiseptics is very low and skin irritation is significantly lower after alcohol application than after detergents (though isopropanol is somewhat more irritating than ethanol).

A 70% solution was a severe eye irritant in rabbit eye tests so the industry keeps this ingredient at low percentages in eye-area products.

One genuine caution: a 70% solution was a severe eye irritant in rabbit eye tests, so it belongs at low percentages in eye-area products, which is where the industry already keeps it.

According to the National Rosacea Society based in the US, you should be mindful of products with these alcohols in the top half of ingredients.