What Is Face Serum? Why And How To Use It

You are not alone in having no earthly idea what a serum is. Even if you’re the proud owner of several serums, it’s not a particularly clear product on it’s surface. Think of the contradictions: It’s moisturizing, but you still use moisturizer. It can be oily, but it’s not necessarily face oil. It can be watery, but is it essence? So many questions and we haven’t even gotten to ingredient lists yet!

Skincare should never stress you out (that would sort of defeat the purpose), so we pooled our collective knowledge, did a bit more research, and compiled a cheat sheet of sorts. There’s not going to be a test, but study up anyway. We hear skincare talk makes great party ice breakers.

What is serum?
Serum is a skincare product you can apply to your skin after cleansing but before moisturizing with the intent of delivering powerful ingredients directly into the skin. Serum is particularly suited to this task because it is made up of smaller molecules that can penetrate deeply into the skin and deliver a very high concentration of active ingredients. This makes them a great tool for targeting specific skincare concerns, like wrinkles. Goodbye, signs of aging!

Is serum a moisturizer?
Yes and no. Serums can be chock-full of moisturizing ingredients (hyaluronic acid, ceramides) to help skin retain moisture. But, that doesn’t make them moisturizers in the traditional sense. Face lotions and creams are richer and create a barrier on top of the skin to keep all that good stuff in.

How often should I use my serum?
Well, this all depends on the serum. Read the label, but once a day will probably cover your bases.

What’s the difference between serum and face oil?
Good question. Traditional serums are water-based. Though, as the face oil trend grows (and there are more and more oils on the market), more oils are marketed as ‘serums.’ Office favorite Vintner’s Daughter Active Botanical Serum comes to mind—it’s very much a face oil. Use whichever floats your boat, with Aida Bicaj’s soothing voice in your head, saying these words: “You have the water-based serums and the oil-based serums. Water-based serums go under the cream and they are so important. They nourish the inner layer of the skin because the molecule is very small so it penetrates—because of the P50, of course. The oil-based serums go on top of the moisturizer because they have a bigger molecule. They’re supposed to keep the cream and whatever you put underneath moist during the entire day. There are so many products out there and everybody claims that it’s the best, so consumers are confused as to what works for them.”

What about essence? Is essence serum?
Essentially. Based on where they come in the routine (after cleansing, before moisturizing) and what function they serve (targeted skincare needs besides simple hydration) serums and essences are very similar. If anything, they differ in texture; Serums are gooier and more concentrated, while essences are watered-down with a more fluid texture (ex. SK-II Facial Treatment Essence). However, it’s mostly a difference in marketing. In Korea, for example, Estee Lauder’s Advanced Night Repair Serum is called an “essence.”

OK but $$$$…
Yes, serums tend to be on the pricier end of the skincare spectrum. But for a pretty decent reason! Remember that bit about being super concentrated and potent? You are getting your bang for your buck here…

Doesn’t serum expire really fast?
Certain potent ingredients often found in serum can become unstable once they come in contact with air. Ascorbic acid (vitamin C), for instace, can oxidize and lose efficacy over time. But thanks to science, modified versions of the ingredient (that are water-soluble, etc.) last longer so they can do your skin more good. Best rule of thumb is to store your vial in a cool, dry place (obviously) and use it up within six months to a year.

Is serum right for your skin?
Probably. Get to know your ingredients first. If you’re…
Acne-prone: Look for vitamin C (increases collagen production, enhances skin’s repair process, and reduces inflammation), retinol (also an antioxidant, reduces inflammation), zinc (soothes irritation, regulates oil production), and salicylic acid (unclogs pores).

Dry: Look for vitamin E (an antioxidant, protects cells from oxidative damage), niacinamide (improves skin elasticity, increases ceramide levels in skin), glycolic acid (gently exfoliates and lightens discoloration), and hyaluronic acid (retains moisture).

Feeling dull: Look for antioxidants like green tea extract, resveratrol, ferulic acid (these combat free radicals, increase effectiveness of sunscreen by day, and promote cellular repair and healing by night).

A word of caution: Because serums are super potent, more is not always better. Be careful before piling it on. Powerful ingredients can irritate sensitive skin. Always patch-test accordingly.

Do you have any recommendations?
Why certainly. Here’s what our team swears by:

+Kiehl’s Midnight Recovery Concentrate: Smells great, texture like a light oil, absorbs quickly, moisturizes without being too heavy, wake up with smooth skin.

+Verso Super Facial Serum: Improves texture, excellent anti-aging results due to retinol 8 (which is eight times more effective than other non-Rx retinols).

+Niod Multi-Molecular Hyaluronic Complex: A top contender in the hyaluronic acid game, feels thicker than most, but penetrates quickly for super plump skin.

+Elizabeth Arden Superstart Skin Renewal Serum: For when you want to get facials every week but simply can’t find the time (or money), doesn’t just brighten your skin—but also improves the efficacy of your other products.

Research by Michaela Waites.

Next up: an explainer on Korean skincare from Peach & Lily’s Alicia Yoon.