The only steps you’re guaranteed to find in a given skin-care routine are cleansing, moisturizing, and sunscreen—but what if your routine has two or three or five more steps to it? It makes sense that there would be some kind of order to layering different serums, creams, toners, and essences, but all the conflicting information and skin-care pseudoscience out there makes it difficult to decide what products you actually need and how to apply them.
In general, most people recommend ordering products by texture and/or pH level: apply lighter, thinner products before heavier creams and lower pH products before higher pH ones. The reasoning goes that application order dictates how various products are absorbed, and therefore, their efficacy.
But how much are these rules actually applicable to real life?
Here’s what to think about when layering your products:
There is some truth to the texture argument thanks to the simple fact that oil and water don’t mix, and the water content of a product affects its absorption into the skin more than anything else, Suzan Obagi, M.D., assistant professor of dermatology and plastic surgery at UPMC, director of the UPMC Cosmetic Surgery and Skin Health Center, and president of the American Academy of Cosmetic Surgery, tells SELF.
“Typically, things that are water-based can be layered on top of [each other], and there shouldn’t be an issue with the penetration of one versus the other,” she explains. “But if you have a cream or an ointment, or a serum that’s oil-based, those should be put on afterwards because anything [water-based] you put on top won’t get through.” In other words, apply those water-based products in any sequence you like, then oil-based products afterward.
That said, “nothing is totally impenetrable,” Evan Rieder, M.D., assistant professor of dermatology at NYU Langone Health, tells SELF, “[so] unless you’re using something like Vaseline—and most people don’t put Vaseline on their faces—you’re probably going to get some sort of penetration.”
Generally, your skin will absorb at least some of each product you put on your face regardless of the order in which they were applied. So even if you apply a water-based product on top of an oil-based one, some will get through. But it would be more effective to apply the water-based ones first.
The pH of skin-care products—meaning how acidic they are—also matters less than you’d think, at least for cosmetic purposes. Apart from benzoyl peroxide, most widely-used active ingredients are acidic, so they have pH values lower than 5. Plus, your skin has its own natural pH (just below 5), which influences the pH of everything it touches.
Applying a pH 4 serum over a pH 3 serum over your pH 4.5-ish face creates a mixture that’s in between all three pH values—not just between 3 and 4. Reverse the serums, and you’d get the same thing. So knowing the pH of your products isn’t really something you need to care about, unless you’re using a prescription treatment as well (more on that later). But if you’re curious about an exact pH, you can always contact the manufacturer.
If there’s a takeaway here, it’s that products don’t form separate layers on top of your skin; everything gets mixed together to some degree, regardless of order. You can minimize product mixing to some degree by letting each layer dry before moving on to the next, Dr. Rieder says, who notes that most products will dry within a couple minutes. But even that isn’t perfect, he says. (And who has that kind of time, anyway?)
Application order matters most when you’re using prescription treatments.
Once you throw prescription medications into the mix, application order becomes more important. Medical treatment beats out cosmetic concerns every time, and you need to ensure you’re getting the full dosage. “Any topical medication that your dermatologist has prescribed…[should] go on first after you cleanse because medicines are absorbed best when the skin is wet, and when there’s nothing between the skin and the medicine,” Dr. Rieder says.
Applying a serum or moisturizer before a topical medication basically dilutes your medication. That said, if you’re using something that’s known to be irritating (such as a retinoid), your dermatologist may actually recommend mixing it with a moisturizer or putting it on after moisturizer to soften the blow a little. But for other treatments, you want to be sure you’re getting the full dose every time.
Dilution isn’t the only concern, however. Topical prescriptions such as retinoids, steroids, and antibiotics are most effective under certain conditions—which often means that pH actually matters. If your serum or toner is acidic (or basic) enough to alter the pH of your medication, it might not work at all.
According to Dr. Obagi, this happens frequently with over-the-counter active ingredients that can interfere with the effectiveness of prescription retinoids when used during the same routine. In particular, benzoyl peroxide and alpha-hydroxy-acids (like lactic and glycolic acid) can deactivate certain retinoids when used at the same time, which is why Dr. Obagi recommends applying acids and/or benzoyl peroxide in the morning and retinoids at night.
If you’re using more than one topical medication (for instance, something for rosacea and something for acne), just ask your dermatologist to write down the order in which you should apply everything so you don’t forget.
The bottom line is that sticking to a precise application order likely won’t make or break your skin-care routine—unless you use prescription medications. Always check with your dermatologist before introducing a new product to make sure it’s compatible with your meds. But if your routine is just for fun or self-care, let common sense be your guide—and if you find yourself agonizing over your routine, take a step back. If you’re not enjoying it, what’s the point?