Everything You Need to Know About Serum—Including Which Ones You Should Be Using

Serums don't have to be some huge mystery. With this basic guide, we're breaking down this beauty routine essential.

When our skin feels dry, we apply a bit of moisturizer; before we head out to tackle the day, we make sure we're protected with the best sunscreen. Most of us have simple skincare routines, but when our pals start talking about multi-step regimes, we wonder what all the fuss is about. Like, what is a serum, and why does it matter? How does it help alleviate our skin concerns? What about serums for our hair? Are they worth the investment?

With thousands of products on the market, understanding the right formula for your specific skincare and beauty needs can be confusing and even overwhelming at times. To make just one area of the beauty world a little more understandable, we spoke with experts to learn more about the different types of serum and what they can do for you. Consider this your essential guide.

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What Are Serums?

Deanne Mraz Robinson, MD, FAAD, a dermatologist in Westport, Conn., defines a serum as a highly concentrated formula with active ingredients designed to penetrate our skin. Every concoction serves its own purpose. When we incorporate serums into our routine, we can enjoy a range of benefits, from hydration and brightening to reducing hyperpigmentation and improving skin texture. Usually sold in smaller bottles and concentrates, serums make a colorful display at beauty supply and skincare stores.

A hair serum offers many of the same benefits, but for our locks. As hairstylist and makeup artist Jules Annen explains, a hair serum is a concentrate for our hair with specific ingredients that boost hair features, from texture and shine to overall vitality. Annen says not all serums are created equal, but many people can find something that works for their hair based on factors including genetics, curl pattern, density, porosity, texture, protein levels, climate, and more.

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All About Face Serums

As you begin to explore the vast world of serums, it's important to choose a formula that appeals to your specific needs. Maybe you would like a more radiant complexion. Perhaps you want to decrease visible signs of aging, or you're after a smoother texture following years of acne trouble. Whatever your issue, here are the most common serums recommended by dermatologists.

Vitamin C serum

What it is: Also known as ascorbic acid, a vitamin C serum serves as an antioxidant helping to protect against free radical damage, according to Marisa Garshick, MD, FAAD, a dermatologist and clinical assistant professor of dermatology at NewYork Presbyterian/Weill Cornell Medical Center.

What it does: Free radicals lurk in the air and are found in pollution. They contribute to dull, lifeless complexions. They also can reveal aging—lines and wrinkles—when not addressed. A vitamin C serum reduces the impact on your skin, leaving you with a brighter, healthier look, Dr. Garshick says.

Who needs it: Everyone! In fact, Dr. Garshick recommends it as a morning serum, so it can work to protect your pores during the day from UV, free radical, and other environmental exposures. "It can be helpful for those who are specifically looking to brighten the skin, and it can also help to even out the skin tone, improving the appearance of dark spots," she says.

Retinol serum

What it is: Available over the counter, a retinol serum is a vitamin A derivative. Dr. Robinson says they contain a lower concentration of the active retinoic acid ingredient than the retinoid cream your dermatologist can prescribe. (Retinoids are higher strength, hence the need for a doctor's prescription.) The only exception is Differin Acne Treatment Gel ($36; ulta.com), which Dr. Robinson says is the first OTC retinoid.

What it does: A retinol serum helps to increase the rate at which skin cells turn over and rejuvenate: simple and effective, according to Dr. Robinson. This is important since slower regeneration causes visible signs of aging, including saggy eyes, deep lines, and more.

"A retinol serum benefits a variety of skin concerns—from acne and scarring to fine lines, wrinkles and collagen synthesis overall by increasing the rate at which dead skin cells shed and new, healthy skin cells replace them," she says. "You will see a brighter, more even skin tone."

Who needs it: Anyone! And it can be especially helpful starting in your mid-to-late 20s. Unlike a vitamin C serum, a retinol serum should be applied to dry, clean skin before you go to bed. For best results, Dr. Robinson recommends applying an antioxidant serum and an oil-free moisturizer on top to prevent excess dryness.

Hyaluronic acid serum

What it is: Another product that fights against aging, a hyaluronic acid serum is a humectant that attracts water and hydration to the skin. This is important since we often lose elasticity and that supple, healthy look as we get older.

What it does: Dr. Robinson says a hyaluronic acid serum will instantly improve the appearance of fine lines and wrinkles by plumping up dry, dehydrated, and thinning skin. It can also soothe redness and irritation. "Overall, hyaluronic acid promotes skin cell regeneration by offering extra hydration and lipid barrier protection to the skin," she says.

Who needs it: For those who have naturally oily, acne-prone skin, Dr. Robinson says a hyaluronic acid serum can be a great solution, since it is oil-free. Your pores will receive the water they need but won't feel clogged, as they might with other formulas. It's a great ingredient for oily, acne-prone skin as an oil-free source of moisture and beneficial to aging skin by hydrating and plumping the skin.

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All About Hair Serums

Your locks need a little TLC, too! That's why various hair serums come to the rescue to cut back on frizz, dry scalp, and other cumbersome issues. Here, hair stylists explain the different hair serum options available.

Frizzy hair serum

What it is: This liquid-based solution works through hair to cut back on flyaways and frizz caused by humidity or other factors, says celebrity hairstylist Trace Henningsen.

What it does: Frizzy hair serums can be used as a quick fix to treat hair at the surface. As Henningsen explains, they work as a styling tool to treat untamed locks while adding shine and protecting hair against environmental aggressors.

Who needs it: Anyone who deals with frizz. According to Henningsen, depending on our hair texture and location, we may deal with more frizz than others. If you are constantly going head-to-head with uncontrollable locks, you may want to use a frizzy hair serum daily instead of seasonally.

The type of dispenser you choose can matter, based on your hair type. "If you have straighter hair, a spray is best, but spray from five to seven inches away so that the hair is not oversaturated," Henningsen says. "For other hair types, there are formulas that are best to squeeze into the hands, running it from mid-shafts to ends along with focusing on any areas at the root with a comb."

Curly hair serum

What it is: Because curl patterns can vary, Annen says there are a plethora of hair serums to address various needs. "If you have finer curls, heavy serums may weigh hair down. If you have tight curls, some serums don't have enough power to define your curls," she says. "Finding the serum that is the best consistency with targeted ingredients is key for curly hair."

What it does: Once you figure out the right formula for your curls, Annen says a curly hair serum assists in aligning the curly strand with others to form a defined wave or curl.

Who needs it: Curly girls unite! Anyone who wants to have more defined, smoother and nourished curls should add a serum to their routine. Annen suggests applying the serum to damp hair, then distributing it onto the midsection and ends of your hair.

Textured hair serum

What it is: When you have textured hair, you may need a little extra serum to tame your locks. As hairstylist Jana Rago explains, hair serums for textured hair are best used as a finishing product to ensure you're ready to greet the world.

What it does: A textured hair serum can smooth out unruly locks without weighing them down like a cream might, Rago says. It can also balance out unwanted texture if you're going for a smoother style.

Who needs it: Anyone who has textured hair and wants to shape, style, and contain your look of the day. Rago says those who have dry curly or wavy hair would benefit from a texture hair serum. For best results, she suggests piecing out the layers of your hair and using a lightweight serum without oil. "Apply a dime-sized amount to the ends of a finished style starting halfway down the hair through the ends. Do not apply serum to the hair around the face as those hairs are weaker and will fall quickly," she says.

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  1. Telang PS. Vitamin C in dermatology. Indian Dermatol Online J. 2013;4(2):143-146. doi:10.4103/2229-5178.110593

  2. Poljšak B, Dahmane R. Free radicals and extrinsic skin aging. Dermatol Res Pract. 2012;2012:135206. doi:10.1155/2012/135206

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