Cleansing and moisturizing are a solid foundation for your skin-care routine, but, truthfully, they can only do so much. If you’re looking to address specific skin concerns—like dryness, dullness, or dark spots—then you may want to kick things up a notch by adding face serums to your beauty regimen. 

Not sure where to start? This primer breaks down everything from what serums are and how they work, to what ingredients to look for and how to use them for your healthiest skin yet. 

What Are Face Serums, Exactly?

In case you’re wondering what a serum actually is: A face serum is a skin-care product that contains a highly concentrated mix of certain ingredients, Debra Jaliman, M.D., a New York City-base board-certified dermatologist, assistant professor of dermatology at Mount Sinai’s Icahn School of Medicine, and author of Skin Rules. 

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Because of their high concentration of active ingredients, serums target individual concerns like dullness, dehydration, breakouts, and fine lines. 

How Do Face Serums Work?

The viscosity of a face serum is a lot lighter than a traditional moisturizer. (Expect a clear, liquid texture from a serum versus the thicker, creamier feel you get from a moisturizer.) 

This ultra-lightweight viscosity allows the active ingredients in the serum to penetrate deeper into your skin, says Joshua Ross, celebrity esthetician and founder of SkinLab in Los Angeles. This one-two punch of highly concentrated active ingredients and deep skin penetration is what makes serums so effective at supporting the health of your skin.

Who Can Benefit From A Serum? 

If you want to address skin dryness, dullness, wrinkles, or dark spots, then you could benefit from using the right serum, says Jaliman.  

However, if you’re allergic to any of the ingredients in a serum, it goes without saying that you should steer clear of it to avoid irritation, says Jaliman. Retinol, salicylic acid, glycolic acid, and essential oils are some common serum ingredients that could trigger an allergic reaction or aggravate your skin. Make sure to do a spot test before diving in if you’re not sure how these ingredients affect you.

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And, if you have sensitive skin, you may want to avoid serums that contain exfoliating acids like glycolic acid, lactic acid, and salicylic acid since those will likely be too aggressive for your fragile skin type, says Ross. 

What Type Of Serum Should You Use?

There are a few different types of serums you can choose from, each with its own unique benefits. 

Some of the most popular serum categories—and the ingredients to look for in them—include:

Antioxidant Serums 

• What they do: Antioxidant serums help protect your skin from free radicals, unstable atoms in the environment that can damage your skin cells and lead to visible signs of aging like dark spots and wrinkles, says Ross. Certain antioxidants, like vitamin C, can also help brighten your skin, adds Jaliman. 
• Who they’re best for: Any skin type can benefit from an antioxidant serum given that we’re all exposed to free radicals. 
• Ingredients to look for: Vitamin C, vitamin E, resveratrol, and green tea are all common and effective ingredients to search for in antioxidant serums, Jaliman says. 
• When to use them: Apply antioxidant serums in the morning under your SPF for added sun protection, suggests Ross. 
• Antioxidant serum to try: Derma E Vitamin C Serum

Healthy Aging Serums 

• What they do: Healthy aging serums help ward off signs of aging, such as wrinkles and hyperpigmentation, in the skin, says Jaliman. 
• Who they’re best for: Choose a healthy aging serum if you’re concerned about fine lines and discoloration. 
• Ingredients to look for: The most popular ingredient in healthy aging serums is retinol, says Jaliman. Retinol is a form of vitamin A that boosts collagen production in the skin to smooth lines while exfoliating the surface of the skin to promote a more even complexion. 
• When to use them: Apply healthy aging serums at night because retinol can make your skin more sensitive to the sun—and always slather on sunscreen in the morning, Ross advises. 
• Healthy aging serum to try: Mad Hippie Vitamin A Serum

Clear Skin Serums 

• What they do: Clear-skin serums help ease existing breakouts and ward off future ones. 
• Who they’re best for: You can benefit from a clear-skin serum if you have oily or acne-prone skin, says Ross.
• Ingredients to look for: Typically, you’ll find an alpha hydroxy acid (AHA), such as glycolic acid or lactic acid, or a beta-hydroxy acid (BHA), like salicylic acid, in one of these serums, says Ross. Both AHAs and BHAs exfoliate the surface layer of your skin to get rid of dead skin cell buildup that can lead to zits. 
• When to use them: As with healthy aging serums, apply these at night (and be diligent with sun protection in the A.M.) because exfoliating acids can leave your skin more sensitive to the sun. 

Hydrating Serums 

• What they do: Hydrating face serums help give your skin an extra dose of moisture, as their name suggests.
• Who they’re best for: These serums are ideal for dry skin in need of extra moisture, says Ross. They’re also a good option for sensitive skin in need of soothing. 
• Ingredients to look for: Hyaluronic acid is the best ingredient to choose in a hydrating serum, says Ross. It’s a humectant that pulls moisture into your skin. Niacinamide and squalene are other good moisturizers to look for in this kind of serum. These ingredients are also calming, making them solid choices for sensitive skin, Ross adds. 
• When to use them: Hydrating serums are gentle enough to use morning and night, says Ross. 
• Hydrating serum to try: Reviva Hyaluronic Acid Serum

How Do You Apply Face Serum?

Now that you know what type of serum is best for your skin, you’re ready to incorporate it into your routine. 

Serum should come between cleansing and moisturizing. To ready your skin for a serum, Ross recommends first doing a thorough cleanse, then using a hydrating toner. This will leave your skin with a little bit of slip and ensure even application of the serum. 

Next, apply anywhere from two to five drops of serum onto your fingertips and gently spread it around your face, lightly patting it into your skin. Follow up with sunscreen, if using the serum in the morning, or moisturizer, if using the serum at night. 

If you’re someone who experiences different skin issues on different parts of your face, you can even customize your routine by using different face serums on each of those areas. For example: “If you have an oily, acne-prone forehead but you have red, sensitive cheeks, you could use an exfoliating anti-acid serum on your forehead and a hyaluronic acid on your cheeks,” says Ross. 

Ultimately, adding this simple extra step to your skin-care regimen can have a significant payoff—all without breaking the bank or making your routine too time-consuming.