Which? Puts 12 Vitamin C Serums Through Lab Tests for Strength and pH

UK consumer organisation Which? has published a fresh round of vitamin C serum testing, dated 15 October 2026. It bought 12 serums itself rather than accepting brand samples, and the line-up spans the whole market, from supermarket and pharmacy brands to luxury names.

The products include several that Indian shoppers will recognise: SkinCeuticals C E Ferulic, The Ordinary Vitamin C Suspension 23% + HA Spheres 2%, La Roche-Posay Pure Vitamin C12, e.l.f. Bright Icon Vitamin C + E + Ferulic, Drunk Elephant C-Firma Fresh, CeraVe's vitamin C serum, a Garnier vitamin C serum and L'Oreal Paris Revitalift Clinical 12% Pure Vitamin C. The rest are UK-focused: Beauty Pie, Lidl's Cien, Simple and The Inkey List.

The method is what makes this worth noting. Independent laboratories measured each serum's vitamin C concentration and its pH, so the test checks whether the strength on the label is actually in the bottle, not just how the serum feels. A cosmetic chemist, who is not named, reviewed every ingredient list, formula and marketing claim, and a panel of 12 testers rated scent and texture. Scores combine four weighted areas: likely effectiveness, tolerance and suitability, formulation quality and user experience.

The free summary gives only broad conclusions. Which? says its top scorer was a clear winner that justifies a higher price, but also that some low-cost serums did well and that spending more does not always bring better results. The product-by-product scores, the name of the winner and the lab readings for strength and pH are reserved for paying members, so we cannot say which serums matched their stated concentration.

Prices in the test are UK prices and do not translate to Indian shelves. For readers here, the useful takeaway is the approach: vitamin C degrades, and a label percentage is a claim until someone measures it. Our serums page lists current Indian prices and ratings for the products we track.