But because this is life, there are, of course, exceptions to the rule. Jhin tells patients who are treating skin conditions with a prescription product to put it on right after cleanser, toner, and essence — no matter its consistency. That’s because you want the active ingredients that are treating the skin condition to have the best chance of going deep, she says.
The Final Step of Your Skin-Care Routine
Here’s yet another special case: Face oil, should you choose to use it, should always go last. That’s because oil is occlusive — meaning it creates a barrier. “Oil can get through moisturizer, serums, and lotions,” says Jhin. “But it doesn’t [work] the other way around. If you put oil on, nothing can get through it. So you want to apply it last.”
And yet! There’s an exception to that exception. While oil should be the last step in your nighttime routine, when it comes to your morning regimen, sunscreen — whether your formula of choice is chemical or physical — should always, always go last. “Other [products]…have a mission to get to the skin and get absorbed and be efficacious. But sunscreen is a shield,” says Jhin. “You want it on the top because it’s blocking the rays from penetrating the skin.” And seriously, no exceptions. (We mean it this time.)
Ingredient Combinations to Avoid
If you’re using multiple active ingredients in your routine, you should always (always!) consult a dermatologist to be sure they can be safely paired. That said, Jhin says she often gets questions about these combos:
Retinol and Vitamin C
While you can use these ingredients at the same time, Jhin suggests waiting at least 30 minutes before applying retinol over vitamin C. That’s because the two ingredients work best at different pH levels (the measure of acidity), so using them together means they may not work as well. But instead of twiddling your thumbs for a half-hour, Jhin suggests using vitamin C in the morning (since it’s an antioxidant that helps protect skin from environmental stressors) and retinol in the evening.
Vitamin C and Alpha Hydroxy Acids (AHAs)
Jhin cautions that this pairing can cause irritation. So consider using vitamin C in the morning and AHAs in the evening.
Vitamin C and Benzoyl Peroxide
Call them sworn enemies or star-crossed lovers — either way, these two simply cannot be together. Benzoyl peroxide, an ingredient commonly used to treat acne, causes vitamin C to degrade, or oxidize, rendering it useless. Womp, womp.
Benzoyl Peroxide and Retinol
The acne avenger strikes again. Don’t pair the ingredient with retinol, as the two “cancel each other out,” says Jhin.
How Long to Wait Between Applying Skin-Care Products
Now that you’ve got the order of application down, it may be tempting to slap on product after product in quick succession. But you wouldn’t be doing yourself any favors: Jhin says a good rule of thumb is to wait 30 seconds to a minute between layers to maximize absorption.