Now, if you type mineral oil into the search bar, you’ll likely come across some hot debate. Some deem it unsafe for skin; others say it’s totally fine. That’s because while mineral oil is petrochemical derived, you can find purified, cosmetic-grade options that are theoretically safe to apply on the skin (as opposed to technical-grade options, which are typically used to lubricate car engines). In fact, products loaded with mineral oil, like petroleum jelly, are commonly used for slugging techniques—the thick, balmy barrier can lock in moisture.
However, even safer, cosmetic-grade mineral oils are not without their issues: First, mineral oil has a very large molecular size, so while it’s highly occlusive, it’s unable to actually penetrate the skin. This can create a host of problems in the long run—and is why many experts have started to criticize its use.
“It more suffocates the skin than anything else,” says Shamban. “The molecular structure is simply too large so it can both clog pores, cause a disruption or even damage to the skin barrier, and ultimately increase transepidermal water loss.” (Remember: You still need some degree of transepidermal water loss for proper skin barrier function, as it signals to your skin cells that it’s time to jump-start repair; if there’s no signaling, your skin cells may think everything is A-OK and won’t repair.) And while the actual oil might not clog your pores, such an occlusive environment can trap dead skin and oil, causing acne to thrive.
Then there’s the environmental component, which is enough of a reason to avoid its use: “Mineral oil is petrochemical derived, meaning it’s environmentally irresponsible to use mineral oil when there are vegetable and fruit oils, like coconut oil, that are more sustainable,” says clean cosmetic chemist Krupa Koestline. It also does not biodegrade well, and it can accumulate in waterways. Remember: To us, clean beauty means it’s safe for both you and the world around you.