The Dewy Edit

Klairs Vitamin C Serum Review: Gentle Enough for Sensitive Skin, Still Brightening

2 min read

Klairs made its name on formulas built for sensitive skin, and their vitamin C serum is the clearest example of that philosophy applied to an ingredient most people associate with stinging and irritation. Worth flagging up front: this is the current reformulated version of the serum Klairs became known for — the original "Freshly Juiced Vitamin C Serum" name has been retired, but the sensitive-skin-first approach carried over.

Why 5% vitamin C, not 20%

A lot of vitamin C serums chase high concentrations (15-20%+ L-ascorbic acid) for maximum brightening, which also maximizes irritation risk and instability — L-ascorbic acid oxidizes fast and can sting on first use. Klairs' formula uses 5% vitamin C alongside niacinamide and EGF peptides, trading some raw brightening power for a formula that's actually tolerable daily, including for skin that reacts to stronger antioxidant serums.

Texture and how it applies

Lightweight, slightly yellow-tinted (normal for a vitamin C formula, not a sign it's gone bad prematurely), and it absorbs without the tackiness some vitamin C serums leave behind. No noticeable sting on application, which is the actual point of the lower concentration.

Who it's genuinely good for

  • Sensitive or reactive skin that wants vitamin C's antioxidant and brightening benefits without the usual irritation trade-off
  • Vitamin C beginners who tried a higher-concentration serum, reacted badly, and assumed the ingredient just "doesn't work" for them
  • Anyone building a dark-spot or dullness-focused routine who wants a daily-use option rather than a rotate-in treatment

Who might not need it

  • If you already tolerate strong vitamin C formulas well and want maximum brightening speed, a higher-concentration serum will outperform this one
  • Vitamin C is light- and air-sensitive — this isn't a "leave the cap off" product, and results depend on consistent use, not a single application

Where it fits in the routine

Serum is step 6 in the 10-step routine. Vitamin C pairs best in the AM routine, underneath sunscreen — it doesn't replace SPF, it works alongside it against oxidative sun damage.

Bottom line: it's not the strongest vitamin C serum on the market, and it's not trying to be — it's the one to reach for if every other vitamin C serum has made your skin unhappy.