You’re ready to establish a good skin-care routine — one that works with your skin type and addresses your skin goals. And in the midst of choosing a cleanser, a retinol, and maybe a mask, you’re also trying to settle on a serum, because you’ve heard about them and think you should be using one. If you're looking to target a specific skin woe, that may be a smart choice.

What Is a Serum and When Do You Use Them?

A serum is almost self-explanatory. “A serum really is just a slippery liquid. It’s in between a true liquid and a cream,” says Angela Lamb, MD, an associate professor in the department of dermatology at Mount Sinai in New York City.

Within your skin-care routine, they are designed to go after your cleanser and before your moisturizer, says Dr. Lamb. These often contain an active ingredient that aims to address a single goal, such as brightening skin tone or fighting wrinkles. And often, they may be able to deliver better results compared with a similar moisturizer. “Serums have a higher concentration of active ingredients than a traditional moisturizer. They are formulated to penetrate the skin versus sit on the surface of skin and lock moisture in, which is the role of a [traditional] moisturizer,” says Deanne Robinson, MD, a board-certified dermatologist in Westport, Connecticut.

How Are Serums Different From Essences and Ampoules?

It’s easy to confuse a serum with other beauty buzzwords, like an essence or ampoule. As Dr. Robinson explains, an essence is a more diluted form of a serum, while an ampoule is highly concentrated but contains fewer active ingredients than a serum. You’d use an ampoule when you need a “turbo dose” of one ingredient to treat a specific skin concern. “A serum is more of a multitasker,” she says. If appropriate, you’d add an essence or ampoule into your routine, alongside a serum.

Which Serum Is Right for You?

In general, a well-chosen serum that takes into account your skin type and goals is safe to use, says Lamb. (For instance, if you are pregnant, you should avoid a serum containing retinol, but you can still use a serum without this active ingredient.)

Serums can be expensive, but to temper the sticker shock, remember this: “When you apply it, you need only one pump, so your product should last you a while,” says Robinson.

With that in mind, here are seven great serums for some common skin-care concerns.

1. To Address Fine Lines and Wrinkles or Improve Texture, Look for Retinol

The natural loss of collagen with age contributes to the formation of fine lines and wrinkles. So what you need right now is to boost skin cell turnover and stimulate collagen production. For that, reach for a retinol serum, says Dr. Lamb. Another plus of retinol: It boosts levels of hyaluronic acid, a natural component of skin that keeps it plump and hydrated, per a study published in May 2017 in the Archives of Dermatological Research. Apply these at night, she says: “Retinols are deactivated by the sun.” One brand she often recommends is RoC.

Try RoC Retinol Correxion Deep Wrinkle Facial Serum, $26.18, Walmart.com.

2. To Smooth Lines and Wrinkles When You Have Sensitive Skin or Are Pregnant, Go for Bakuchiol

Bakuchiol is a natural retinol alternative, derived from the leaves of the plant Psoralea corylifolia, per Paula’s Choice Skincare. It functions in skin just like a retinol, but is less likely to set off reactions (such as redness and peeling), so it can be a good option for those who need a gentler anti-aging product, says Robinson. Unlike retinol, it is also safe to use during pregnancy. One study, published in February 2019 in the British Journal of Dermatology pitted a 0.5 percent bakuchiol cream against a 0.5 percent retinol cream, and found that after 12 weeks, both equally reduced the appearance of wrinkles and hyperpigmentation — but the bakuchiol product triggered fewer side effects.

Try Biossance Squalene + Phyto-Retinol Serum, $72, Sephora.com.

3. To Hydrate Combination or Oily Skin, Go for a Hyaluronic Acid

Hyaluronic acid can hold 1,000 times its weight in water, per Paula’s Choice, so you can imagine why dermatologists recommend it as a top-notch hydrator. There’s no reason to use a moisturizing serum and a moisturizer, but because a hyaluronic acid serum is so lightweight, it’s best as a replacement for a lotion or cream if a traditional moisturizer causes breakouts, says Lamb. She likes the Neutrogena Hydro Boost line, which is noncomedogenic, meaning it’s less likely to clog pores and lead to a breakout, according to the American Academy of Dermatology.

Try Neutrogena Hydro Boost Multivitamin Booster Face Serum With Hyaluronic Acid, $18.27, Neutrogena.com.

4. To Reduce the Appearance of Pores and Prevent Breakouts, Try Salicylic Acid

If you feel like your pores are staring back at you in the mirror, a specially targeted serum can help you clear out the gunk. “Large pore size is the result of pores that are clogged with dead skin cells and mixed with oil,” says Robinson. She recommends using a combination of alpha hydroxy acids (AHAs) (such as glycolic or lactic acid) to decongest pores, along with salicylic acid, which is a beta hydroxy acid (BHA). Salicylic “softens and dissolves keratin that may be clogging the pore,” she says. Robinson likes the product SkinCeuticals Blemish + Age Defense, which contains both glycolic and salicylic acids. (Pro tip: Use a glycolic wash before this serum for even better results.)

Try SkinCeuticals Blemish + Age Defense, $92, Dermstore.com.

5. To Lift Sag, Opt for a Serum Packed With Peptides

When skin needs more bounce, go for peptides. “Peptides are chains of amino acids that form proteins, which support skin structure. They’re great for adding support to lax skin,” says Robinson. She recommends Alastin Restorative Skin Complex. The serum contains TriHex Technology, a blend of peptides and botanicals; research from the company published in the March 2018 issue of the Journal of Cosmetic Dermatology shows that using the product for 12 weeks stimulated collagen and elastin production to lessen the appearance of wrinkles and sag.

Try Alastin Restorative Skin Complex, $195, Alastin.com.

6. To Erase Pigment Problems and Boost Brightness, Try Three Antioxidants and Peptides

When it comes to tackling dull or spotted skin, dermatologists love vitamin C. Research shows that vitamin C, a potent antioxidant, is effective in lightening unwanted pigmentation and preventing future dark spots, per a review of 31 trials published in February 2019 in the Journal of Clinical and Aesthetic Dermatology. Robinson recommends Pure BioDerm Antioxidant Super Serum, which contains vitamin C, along with ferulic acid and phloretin (the two other antioxidants) and peptides. Vitamin C is known for being a finicky ingredient, and the presence of ferulic acid “extends the life and effectiveness of vitamin C,” says Robinson. Phloretin, another potent antioxidant, has also been shown to stabilize C and ferulic acid, according to research. Turns out, they’re the perfect trifecta. (Full disclosure, this is a product that Robinson codeveloped.)

Try Pure BioDerm Antioxidant Super Serum, $49, Amazon.com.

7. To Protect Skin and Slow Down Aging, Go for Resveratrol

Resveratrol is a polyphenol, a plant-compound found in grapes. (It’s one reason why red wine may be heart protective in moderation, notes a review published in May 2017 in Current Medicinal Chemistry.) “Resveratrol is one of my favorite ingredients, as it’s a really great antioxidant with a lot of research behind it,” says Lamb. Not only has it been shown to stimulate collagen production, but its antioxidant properties protect skin from free radical damage and slow down aging, per a review published in May 2018 in the Journal of Cosmetic and Laser Therapy. One great option: Caudalie Resveratrol Lift Firming Serum.

Try Caudalie Resveratrol Lift Firming Serum, $82, Dermstore.com.

Should You Try a Stem Cell Serum?

Some of-the-moment serums are incorporating stem cells in their formulas. These are premature cells, and they’ve traditionally been used in treating conditions like cancer. Topically, the theory is that they may help cells rejuvenate, so that skin appears more youthful. Lamb has her doubts, though: “Technically, stem cells are live. To then put them in a cream that is unlikely to be refrigerated or have them in an environment unlikely to keep them alive is a bit gimmicky,” she says. Not to mention, these serums are extremely pricey. Until more is known, save your money.