Isopropyl Myristate: The Silky Ester Behind Premium Creams and Bath Oils

Isopropyl myristate is a branched ester, built from isopropyl alcohol and myristic acid. Formulators add it to premium face creams as one ingredient among several in the oil phase, and to bath oils, where it can make up most of the formula. Colin Sanders, the cosmetic chemist behind Colin's Beauty Pages, has handled the raw material directly for years and describes the feel as 'reminiscent of velvet.' He adds that in a cream it delivers less than the neat oil promises. In a bath oil, he says, it earns its place.

Isopropyl palmitate is the ester's close relative, built from palmitic acid instead of myristic acid. Formulators who want a specific texture sometimes blend several branched esters, isopropyl myristate, isopropyl palmitate, and others, into a single formula. Sanders writes that such blends signal deliberate work by a formulator chasing a specific skin feel.

The ingredient's reputation for causing blackheads traces back to animal studies run in the 1960s. Researchers applied test substances, including isopropyl myristate, to the inside of rabbit ears and checked for comedones, the plugged follicles that form blackheads. Sanders describes the problem directly: different labs running the same test on isopropyl myristate reached opposite conclusions, some reporting a comedogenic effect and others finding none. He writes that the research became an area where 'the more papers you read, the less you understood what was going on.'

Rabbit ear skin differs structurally from human skin, so a result in one doesn't transfer automatically to the other. Agreement between laboratories on the rabbit data itself was poor, which undermines the original premise used to brand isopropyl myristate as a pore clogger. No consistent human clinical data has confirmed the rabbit-ear findings in the decades since those studies ran.

Isopropyl myristate is listed as safe for cosmetic use, with consumer information on it published through cosmetics.info, a resource Sanders points readers toward. He writes that websites branding the ingredient as harmful do so from ignorance or from a wish to sell inferior products at a markup. Over decades of applying isopropyl myristate directly to his own skin, Sanders reports, it hasn't given him a single blackhead.