Vitamin C is one of those supplements that most everyone has been gulping (thanks, Tropicana) and gobbling (in the shape of Flinstones chews) since childhood. So, considering it’s straight from the Stone Age (kidding), it’s not exactly new, but it is a potent antioxidant when ingested andslathered on your skin.

On the package, you might see the words “L-ascorbic acid” which is the scientific name for the star player. According to experts, vitamin C in skin care works because the antioxidant powerhouse helps to neutralize free radicals, which cause a chain of cellular reactions responsible for aging the skin in wide-ranging ways from dark spots to sagging.

The only problem? The antioxidant is hard to stabilize, which means that it expires—and fast—and some products contain only a negligible amount of vitamin C. Those “buts” can render the pricey serums useless to your complexion. So, here, 7 dermatologists help point you to formulas that are both shelf-stable and packed with active ingredients so you get all the skin-boosting benefits.

Keep scrolling for their top vitamin C picks.

1. ISDIN Flavo C Ultraglican Ampules, $102

“This ultra-concentrated skin booster has vitamin C and ultraglican, which stimulates hyaluronic acid production,” explains Dr. Waldorf. “The ultraglican boosts the skin’s ability to hold moisture as vitamin C protects against oxidative stress. Use it in the morning before applying sunblock for protection against ultraviolet radiation and pollution.” —Heidi Waldorf, MD

2. Drunk Elephant C Firma Day Serum, $80

“It’s a gel formula, which is cooling and spreads easily,” explains Dr. Mack. “Vitamin C and ferulic acid naturally brighten skin and help protect against photo-damage, while pumpkin and pomegranate enzymes mildly exfoliate and help with cellular turnover. Apply a pea-sized amount daily to clean skin because it goes into the skin best when applied after cleansing.” —Lian Mack, MD

3. Biossance Squalane + Vitamin C Rose Oil, $72

“The addition of squalane helps prevent moisture loss from skin, making skin more hydrated with continued use,” explains Dr. Nazarian. “It’s plant-derived, oil-soluble, and absorbs quickly into the skin. Apply 2 to 3 drops in the morning and night to clean, dry skin on your neck and face, using circular motions.” —Rachel Nazarian, MD

4. SkinCeuticals C E Ferulic, $165

“In the morning, apply 5 drops to the entire face,” instructs Dr. Chapas. “It contains a high concentration of vitamin C, which evens pigmentation and prevents sun damage throughout the day. Be aware: Light can oxidize it, so throw it out if it becomes orange or brown.” —Anne Chapas, MD

5. NO7 Youthful Vitamin C Fresh Radiance Essence, $25

“Ideally, you should use it twice a day,” says Dr. Bowe. “It’s light, fast-absorbing, and is packed with potent ingredients to provide skin with lasting, long-term benefits. If you like to layer your products, apply serum first and with a daily moisturizing sunscreen in the morning and night cream at night. If you prefer to combine two steps, simply add a few drops of the serum into a quarter-sized dollop of moisturizer (or night cream), mix them together, and apply as one.” —Whitney Bowe, MD

6. Algenist Genius Ultimate Anti-Aging Vitamin C+ Serum, $118

“Vitamin C products are particularly effective in the a.m., when it can act as a barrier to help oxidative stress from UV rays, pollution, and smoke,” explains Dr. Chiu. “This one is great because it’s paraben, sulfate, and phthalate free and doesn’t contain any synthetic dye, triclosan, or GMOs. It’s also hypoallergenic and non-comedogenic so it works on all skin types.” —Annie Chiu, MD

7. Vichy LiftActiv Vitamin C Serum, $29

“This is the biggest vitamin C launch for 2018,” says Dr. Gilbert. “This formula is extremely light and has only 11 ingredients. It doesn’t contain any nasties like parabens, silicones, or artificial fragrances. It’s sort of a stealth price point, that allows you to get access to a highly effective product for not a lot of money. When you put it on, it feels light and doesn’t sting or burn and the hyaluronic helps it go on smooth.” —Erin Gilbert, MD, PhD

By the way, by just putting on a vitamin C serum, you create a glowy finish called “skin glazing” but if you’re not about that expired life, here’s how to tell if yours has gone bad.