Acetylated Lanolin

Acetylated Lanolin is just lanolin (the waxy stuff sheep produce to waterproof their wool) with acetyl groups tacked on.

Chemically, it's the acetyl ester of lanolin and that small tweak makes it less tacky + more water-repellent.

This is why formulators use it as an emollient and occlusive to soften skin and slow water loss.

CIR data shows it's used up to 7% in makeup foundations but older survey showed use as high as 50% in eye and other makeup. The CIR Expert Panel has also concluded it's safe as currently used with no restrictions on lanolin-derived ingredients under EU cosmetic rules.

Allergy-wise, lanolin is a known modest contact allergen. 3.3% of 43,691 tested dermatitis patients reacted to a lanolin marker between 2001 and 2018 and people with chronic inflammatory skin conditions or broken skin are at the higher end of that risk.

This ingredient may not be fungal acne safe. The Malassezia yeasts can't make their own fatty acids and pull them out of wax esters/sterol esters, which is what lanolin is built from. No study has tested this ingredient against Malassezia, so it's best to patch test if you're unsure.

Is it comedogenic?

In Fulton's 1989 rabbit-ear survey, Acetylated Lanolin scored 0 for comedogenicity and 0 for irritancy.

This ingredient is often confused with Acetylated Lanolin Alcohol which is a different ingredient with a comedogenic score of 4 and irritancy score of 2.