Here’s Exactly When To Apply A Serum In Your Skin Care Routine

There is an order of operations for your skin care routine. Washing your face as the first step makes sense for practical reasons — you want to start with a clean canvas to soak up the nourishing goodness the rest of your regimen provides. But other parts are more nebulous. For example: Do serums go before or after your moisturizer?

Generally, the consensus among dermatologists is that your serum should be applied before your moisturizer. Think of it as the middle child of your beauty routine: It’s meant to be sandwiched because of factors like the molecular weight of the formula, the base of the serum, and the time of year you’re using it. Here, derms explain everything you need to know about the product category, which happens to be arguably the most important part of your skin care regimen.

What Is A Serum?

A serum is a targeted treatment within your routine that is known for doing a large chunk of the transformative work on your skin. They will feature star ingredients like vitamin C, retinol, bakuchiol, and chemical exfoliants to treat hyper-specific skin concerns — think evening out texture, fading dark spots, reducing the appearance of fine lines, and fighting breakouts. Moisturizers, meanwhile, have a more general goal: keeping your skin hydrated.

You can choose from two main serum categories: those that are oil-based and those that are water-based. “Most serums are water-based,” says Dr. Diane Madfes, M.D., FAAD, a board-certified dermatologist. She notes these formulas usually contain active ingredients like hyaluronic acid, vitamin E, and ferulic acid, and tend to be lighter in texture, which makes them better for acne-prone skin.

Oil-based serums, on the other hand, are usually used for retinols, says Madfes, though you can find other MVP actives in the formula as well. The perk of these is that the oil works as a buffer that helps slowly release the potent ingredient (like retinol) into your skin while providing moisture to combat potential irritation.

Do You Apply Serum Before Or After Moisturizer?

The complete skin care routine order calls for your cleanser, toner (if you use one), serum, moisturizer, and your SPF, respectively. The general rule of thumb is that your products should be applied in order of thinnest to thickest in their consistency, says Dr. Lian Mack, M.D., a board-certified dermatologist and rep for Catrice Cosmetics.

Serums go before your moisturizer because they’re normally lighter than a face cream, balm, oil, or lotion. “Serums are formulated with small molecular weight actives so they penetrate into deeper skin layers,” says Dr. Loretta Ciraldo, M.D., FAAD, a board-certified dermatologist and founder of Dr. Loretta skin care. Moisturizers, on the other hand, are less liquid and more viscous and creamy, she explains. Madfes adds that “they’re typically denser and create a barrier to keep all the ingredients in.” So the lightness of the serum would have a hard time making it through the barrier that a good moisturizer is meant to create on the skin. Think of trying to run jelly, compared to water, through a strainer.

There’s an exception to the serum-before-moisturizer rule, however: If you’re using an oil-based serum, Madfes says you can actually skip your moisturizer altogether. “Just make sure you give your oil-based serum at least 15 minutes to be absorbed by your skin before applying anything else, like sunscreen,” she tells Bustle. Another thing to note? “Many people don’t need a moisturizer over their serum during the summer months,” Madfes adds. If your skin’s on the oily side or if you’re breaking out, just ditch the face cream and let your serum work double duty. In the winter, however, Madfes says moisturizer should always be used over your water-based serums. And there you have it.

Studies referenced:

Lin, T-K. (2018). Anti-Inflammatory and Skin Barrier Repair Effects of Topical Application of Some Plant Oils. International Journal of Molecular Sciences. doi: 10.3390/ijms19010070

Experts:

Dr. Loretta Ciraldo, M.D., FAAD, a board certified dermatologist and founder of Dr. Loretta skin care

Dr. Lian Mack, M.D., board-certified dermatologist and rep for Catrice Cosmetics

Dr. Diane Madfes, M.D., FAAD, a board-certified dermatologist