Every Question You Had About Serums, Answered From Top Derms

The struggle is real and we get it. When you have multiple products that make up your skincare routine, it can be confusing to know which order is most beneficial. Serums, since they contain potent actives, should be applied to clean, freshly washed skin—that way they have more opportunity to penetrate the skin and do their work.

According to board-certified dermatologist and founder of MMSkincare, Ellen Marmur, MD, skincare products should be applied from thinnest to thickest. But take note, that doesn’t include your cleanser. Your cleanser should always go first, no matter how thick or thin it is. “If you choose to use a serum, it’s usually applied after cleansing the skin and before the moisturizer,” Marmur says. 

Engelman agrees that thinnest to thickest is the go-to rule of thumb because it allows each layer to be fully absorbed by the skin. “If you put a serum on top of a moisturizer, the serum won’t be fully absorbed since the smaller molecules cannot penetrate the larger ones.” So, when in doubt, stick to thick creams as your last step and lightweight serums in the middle. 

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