There are many skin care ingredients that do amazing things for your face, but they usually target only one or two problems at once. So if, for instance—not that I'm speaking from experience—you're an ex-smoker with hyperpigmentation and acne-prone skin who doesn't want to use a million products and spend a million dollars, you have some tough choices to make.

Vitamin C serums have been touted as cure-all products that beauty bloggers love to claim can help almost all common skin concerns—including sun damage, fine lines, acne scars, and under-eye bags. But to find out if a Vitamin C serum really is the magic potion everyone's claiming, we turned to the experts.

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What do Vitamin C serums do—and how?

Vitamin C is a that neutralizes free radicals, which are generated by our bodies when exposed to certain conditions, including pollution and UV rays. —if the free radicals inundate the body and prevent its ability to regulate them, oxidative stress can occur. Free radicals can negatively impact DNA, lipids, and proteins; cause a variety of diseases; our cells and disrupt the skin's ability to repair itself; and slow down collagen production.

Applying antioxidants like vitamin C can with this stress… so what are the resulting benefits?

Anti-Aging Benefits

"Serums with vitamin C also , which slows as we age," says , M.D., a board-certified dermatologist and author of the book . Collagen is a structural protein that holds cells together, strengthens skin, and gives it elasticity—all of which are important for a healthy, toned complexion. By boosting our skin's ability to make collagen, a Vitamin C serum helps soften existing fine lines and —while preventing new ones from forming.

Fight Against Hyperpigmentation

"Vitamin C serums fight hyperpigmentation by inhibiting the tyrosinase enzyme and preventing melanin production," says , M.D., a board-certified dermatologist. The process brightens dark spots without lightening skin tone overall.

Help With Acne and Acne Scarring

Vitamin C is , and a vitamin C serum can both help clear up acne and reduce the redness associated with it—as well as improve skin texture. "Due to the pro-collagen and pro-elastin effects of vitamin C, acne scars may also be reduced," Klein says. If you have acne, make sure to exfoliate before applying the serum for better penetration.

Protection Against Sun Damage

A vitamin C serum may be able to reverse some of the your sunbathing days have wreaked on your skin and may even . But while a Vitamin C serum is many things, a sunscreen it is not, so please don't throw away your SPF. However, using a vitamin C serum so it's a great component of your daily UV-fighting routine.

Can you layer a vitamin C serum with other skin care products?

"Dermatologists love layering products!" Klein says. "I generally advise going from lowest to highest pH, like using either an alpha or beta hydroxy acid cleanser in the morning followed by the vitamin C serum."

A vitamin C serum will not lose its potency if applied in an incorrect order, but applying lowest to highest pH when layering skin products will increase absorption—and therefore efficacy, according to Klein. Feel free to add peptides, hyaluronic acids, and B5 after the Vitamin C serum. One exception is products with niacinamide. "Niacinamide turns into niacin when mixed with Vitamin C," cautions Jaliman. Niacin, although not harmful, can cause short-term skin redness and tingling in people with sensitive skin.

Generally speaking, you'll want to use your Vitamin C serum after you cleanse and tone, but before you use moisturizer. Take a few drops in the palm of your hand and massage gently into the skin of your face and neck with your fingertips. This can be done once or twice a day.

What should you look for in a vitamin C serum?

"Getting a high level of vitamin C to boost collagen—without bringing on redness and irritation—is the key to vitamin C products," Klein says. Her recommendation is to use a serum that has between . "Vitamin C should be one of the first ingredients listed on the label," Jaliman adds.

Vitamin C is unstable and will degrade over time, losing its efficacy. Interacting with heat, , and speeds up the process, which is why you should look for serums in opaque, airtight bottles.

There are many different derivatives of vitamin C, including ascorbic acid, magnesium ascorbyl phosphate, and sodium ascorbyl phosphate—so if one derivative is too irritating, you can always try another. L-ascorbic acid is one popular form of vitamin C, and although it's than other forms of vitamin C, it's also less irritating. Look for vitamin C serums that contain ferulic acid, which helps stabilize the vitamin and creates an ideal pH level.

How do I pick the best vitamin C serum?

Vitamin C serums often contain other skin-saving ingredients—if you have dry or lackluster skin, look for a serum that contains hyaluronic acid, which is incredibly moisturizing. Both Klein and Jaliman rave about the . In addition to hyaluronic acid, the Mad Hippie formula contains (which, as we mentioned, can make Vitamin C more stable) and v, which has been shown to increase vitamin C's photoprotective effects.

Another favorite with both doctors and seemingly every beauty blogger out there is the . As the name suggests, the SkinCeuticals formula also contains ferulic acid and Vitamin E.

Klein is also a fan of the . The Obagi serum comes in 3 strengths, 10, 15, or 20 percent, so you can build up your tolerance to a higher percentage of vitamin C. For those looking for even more potency, has the highest concentration of Vitamin C available.

Masha Vapnitchnaia is a travel and lifestyle writer and researcher. She has been traveling her whole life, taking her first flight at the age of four and taking 100 more since. Follow her pilgrimages at

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