Myristyl Lactate

Myristyl Lactate is a simple ester made from myristyl alcohol and lactic acid.

Despite the name, it doesn't act like an exfoliating AHA in a finish product because the lactic acid part is locked up and not floating around as a free acid.

In a finished formula, it acts as an emollient and slip agent that gives a smooth, non-greasy feel (also why it's so common in color cosmetics).

Rat studies show it works as a penetration enhancer: 3-5% propylene glycol noticeably increased how much indomethacin got through the skin by acting on the stratum corneum; so just a head's up that it can carry other ingredients in with it.

Older concentration reviews found it can be used up to 25% but it's usually used in much lower amounts.

The 2013 Personal Care Products Council survey reported a maximum of 13.2% in lipstick, 0.01-13.2% in leave-on products, 0.79-11.2% in rinse-off, and 3.5-7.2% in eye area products.

Safety-wise, the data is reassuring; there's no eye irritation in rabbit tests and a lipstick containing 13.8% was non-irritating and non-sensitizing in a human repeat insult patch test.

The one caveat is that undiluted Myristyl Lactate was moderately irritating in one Draize study. This is normal for a neat ester and not really relevant to how it gets used in cosmetics.

Allergy wise, it's not a known contact allergen and allergy risk is very low.

Pore clogger

This ingredient does have a comedogenic rating of 4, but this doesn't mean a formula with this ingredient will clog pores. Human testing has proved that any finished product with this ingredient won't automatically make you break out; it really comes down to concentration, formula, and your skin.

Fungal acne

The Malassezia yeast feeds on fatty alcohols with a chain length above 12 carbons, and this ingredient is created from myristyl alcohol (C14). It may not be fungal acne safe.