The 7 best vitamin C serums, from L-ascorbic acid to gentler forms

Key takeaways

• The most researched form of vitamin C on skin is L-ascorbic acid. Reviews suggest 10% to 20%, at a pH below 3.5, for it to absorb well.

• Our top pick is Paula’s Choice C15 Brightening Super Booster: 15% L-ascorbic acid with ferulic acid and vitamin E, at pH 3.1 to 3.5, with no fragrance.

• On a budget, Timeless 20% Vitamin C + E Ferulic Acid Serum and Geek & Gorgeous C-Glow both use L-ascorbic acid for under $30.

• For sensitive skin, gentler forms like ascorbyl glucoside or tetrahexyldecyl ascorbate tend to sting less, though they’ve been studied less.

• Vitamin C isn’t a sunscreen. Use it in the morning under a broad-spectrum SPF 30 or higher.

What vitamin C does, and what to look for

Vitamin C is an antioxidant, and on skin it’s mostly used to brighten dullness and dark spots and to support the look of firmer skin. It doesn’t replace sunscreen: a 2013 review notes that vitamin C “does not absorb UV light,” and that sunscreens alone block only about 55% of the free radicals UV exposure produces, which is why it recommends pairing sunscreen with a topical antioxidant.

The form and the formula matter:

• Strength. A 2017 review says a product needs more than 8% vitamin C to be effective, that going above 20% doesn’t add benefit and may irritate, and that reputable products are in the 10% to 20% range.

• pH. In a 2001 study on pig skin, L-ascorbic acid had to be formulated at a pH below 3.5 to enter the skin, and absorption peaked at 20%.

• Form. Derivatives like ascorbyl glucoside, sodium ascorbyl phosphate and tetrahexyldecyl ascorbate are more stable and often gentler, but there’s less research showing how well they work on skin.

• Packaging. Vitamin C breaks down with light and air and can turn yellow or brown. Cleveland Clinic suggests choosing a product in dark or tinted glass.

We compared each product on its published ingredient list, not on hands-on testing. We looked at its form and strength of vitamin C, pH where the brand states it, supporting antioxidants, whether fragrance is listed, storage and the price.

1. Paula’s Choice C15 Brightening Super Booster: best overall

Paula’s Choice C15 Brightening Super Booster is a concentrated serum with 15% L-ascorbic acid, ferulic acid and vitamin E. Paula’s Choice says it’s formulated at pH 3.1 to 3.5 and contains no fragrance, dyes, silicones or parabens.

Key features:

• 15% L-ascorbic acid. It sits in the middle of the 10% to 20% range.

• Ferulic acid and vitamin E. They’re antioxidants often paired with vitamin C.

• Stated pH. Paula’s Choice lists a pH of 3.1 to 3.5.

Tradeoff: at $59 for 0.67 fl oz, it’s one of the more expensive picks per ounce.

Best for: most skin types that want a classic L-ascorbic acid serum.

Price: $59 for 0.67 fl oz.

2. Timeless 20% Vitamin C + E Ferulic Acid Serum: best high-strength budget pick

Timeless 20% Vitamin C + E Ferulic Acid Serum has 20% L-ascorbic acid with vitamin E, ferulic acid, panthenol and sodium hyaluronate, in a short ingredient list. Timeless labels it fragrance-free and ships it in glass bottles with a pump.

Key features:

• 20% L-ascorbic acid. It’s the top of the range reviews suggest.

• Short ingredient list. It has 11 ingredients.

• Several sizes. It comes in 1 oz, 1.7 oz and 4 oz.

Tradeoff: Timeless recommends keeping it in the refrigerator after opening and using it within three to six months.

Best for: oily or normal skin that tolerates a strong serum and wants value.

Price: $27.95 for 1 oz.

3. Geek & Gorgeous C-Glow: best under $15

Geek & Gorgeous C-Glow has 15% L-ascorbic acid with ferulic acid and vitamin E, at a stated pH of 3 to 3.4. Geek & Gorgeous labels it fragrance- and essential oil-free and recommends storing it in the fridge.

Key features:

• 15% L-ascorbic acid. It’s the same strength as our top pick, at a fraction of the price.

• Stated pH. It’s within the range the research points to.

• Fragrance-free. Geek & Gorgeous says so on the product page.

Tradeoff: it lasts three months after opening, and Geek & Gorgeous itself doesn’t recommend it for sensitive, redness-prone skin.

Best for: people who want to try L-ascorbic acid for very little money.

Price: $14.90 for 30 ml.

4. The INKEY List 15% Vitamin C + EGF Serum: best for sensitive skin

The INKEY List 15% Vitamin C + EGF Serum uses 15% ascorbyl glucoside, a stable vitamin C derivative, with what The INKEY List calls 1% EGF, a plant-based peptide listed as oligopeptide-1. The INKEY List labels it fragrance-free, says it has a pH of 6.8 to 7.2, and says it doesn’t need refrigerating.

Key features:

• Near-neutral pH. It’s far less acidic than the L-ascorbic acid serums here.

• Stable form. The INKEY List says to use it within six months of opening.

• Published study figures. In a four-week consumer trial of 64 people, 87% agreed their skin looked brighter.

Tradeoff: ascorbyl glucoside has much less research behind it than L-ascorbic acid.

Best for: sensitive skin that doesn’t tolerate acidic vitamin C.

Price: $20 for 30 ml.

5. Medik8 C-Tetra: best oil-based serum

Medik8 C-Tetra is a lightweight, oil-based serum with 7% tetrahexyldecyl ascorbate, an oil-soluble vitamin C derivative, in jojoba oil with vitamin E. Medik8 calls it a lipid vitamin C serum and reports that 95% of people in a consumer study agreed it’s gentle on their skin.

Key features:

• Oil-soluble vitamin C. Tetrahexyldecyl ascorbate is more stable than L-ascorbic acid.

• Jojoba oil base. It suits dry skin that likes an oil-based serum.

• About 200 uses per bottle. That’s Medik8’s estimate.

Tradeoff: it contains grapefruit peel oil, along with limonene, citral, linalool and geraniol, which may not suit sensitive skin.

Best for: dry skin that wants a gentle, oil-based vitamin C.

Price: $53.

6. La Roche-Posay Vitamin C12 Serum: best drugstore pick

La Roche-Posay Vitamin C12 Serum has 12% L-ascorbic acid with salicylic acid, vitamin E, hyaluronic acid and neurosensine. In a clinical study of 63 people who used it twice a day for two months, La Roche-Posay reports a 41% reduction in the look of wrinkles and a 70% improvement in radiance.

Key features:

• 12% L-ascorbic acid. It’s within the 10% to 20% range.

• Published study figures. La Roche-Posay reports them from clinical scoring.

• Suitable for sensitive skin. La Roche-Posay says so, and says it’s better suited to dry and normal skin.

Tradeoff: its ingredient list includes fragrance and alcohol.

Best for: dry and normal skin that wants a widely available L-ascorbic acid serum.

Price: $44.99.

7. Naturium Vitamin C Complex Serum: best in an airless pump

Naturium Vitamin C Complex Serum combines sodium ascorbyl phosphate and ascorbic acid with glutathione, Kakadu plum and vitamin E. Naturium labels it fragrance-free, lists a pH of 5.5 to 6.5, and packages it in an airless pump.

Key features:

• Airless pump. It limits air exposure, which vitamin C is sensitive to.

• Several antioxidants. Glutathione, Kakadu plum and vitamin E are all in the formula.

• Fragrance-free. Naturium says so on the product page.

Tradeoff: its pH is well above 3.5, and Naturium doesn’t state how much vitamin C it contains.

Best for: people who want an easy, fragrance-free vitamin C serum at a low price.

Price: $21 for 30 ml.

How to use a vitamin C serum

• Apply it in the morning. Cleveland Clinic suggests using it in the morning as a backup to sunscreen, since the two work together.

• Put it on after cleansing, before moisturizer. Our guide to skincare routine order shows where serums go.

• Always follow with sunscreen. Our guide to mineral vs chemical sunscreen explains how to pick one.

• Start slowly if you’re sensitive. Use it every other day at first, especially with L-ascorbic acid.

• Watch the color. If it turns dark orange or brown, it has likely oxidized.

• Give it time. Cleveland Clinic says it takes about three months to really see the effects. For stubborn marks, our guide to fading dark spots covers other ingredients with evidence.

Frequently asked questions

What percentage of vitamin C serum is best?

Reviews suggest 10% to 20% for L-ascorbic acid. Going above 20% doesn’t seem to add benefit and may cause irritation.

Can I use vitamin C every day?

Yes, for most people. Once a day in the morning is typical. If it stings, cut back to every other day or try a gentler derivative.

Can I use vitamin C with niacinamide or retinol?

You can use vitamin C with niacinamide, and our guide to what niacinamide does explains why the old warning doesn’t hold up. Many people use vitamin C in the morning and retinol at night. Our guide to retinol for beginners covers how to start.

How do I know if my vitamin C serum has gone bad?

L-ascorbic acid turns yellow as it oxidizes, and then darker. A 2013 review notes that oxidized vitamin C gives a yellow color. A dark orange or brown serum is past its best.

Does vitamin C serum help with dark spots?

It may help. A 2023 review found vitamin C lightened pigmentation, though long-term use may be needed. Our guide to fading dark spots covers what the research shows.