Paula's Choice BOOST C15 Super Booster 15% Vitamin C Face Serum, 0.67 Fl Oz

Why it's worth it

This is 15% pure L-ascorbic acid with ferulic acid and ergothioneine, packed in an opaque bottle small enough that you'll finish it before it turns. It's formulated for all skin types, sensitive included, and it disappears under moisturizer and sunscreen without pilling.

This is the formula the research supports, without extras that muddy it. Published work on topical L-ascorbic acid puts the useful range at 10 to 20 percent, with measurable fading of hyperpigmentation showing up around the twelve-week mark. At 15%, this sits in the middle of that window. Paula's Choice research also found that pushing past 20% mostly buys you redness and water loss, not results.

The ferulic acid isn't decoration. Duke research published in the Journal of Investigative Dermatology found that pairing L-ascorbic acid with vitamin E and ferulic acid gave roughly eight times the antioxidant protection of vitamin C on its own. That combination is why this style of formula became the reference point for the whole category. You're getting the same architecture in a much smaller, more manageable bottle.

From our review of 8 vitamin c serums, by Sarah Wright, Editorial Associate

What we like

• +This is the formula the research supports, without extras that muddy it
• +The ferulic acid isn't decoration
• +Paula's Choice calls this a booster, and that's genuinely how it acts
• +The packaging is quietly one of the best things here

What to know

• –The texture is so runny it's genuinely wasteful
• –A minority of buyers say they've gone through several bottles and seen nothing at all