Niacinamide appears in many skincare products, but an INCI listing does not tell you whether a finished formula will reproduce the results of a clinical trial. The useful question is narrower: what was tested on human skin, at what concentration, and against which control?
The clearest trial used a 5% moisturiser
In a 12-week, double-blind split-face study, 50 white women aged 40–60 used a moisturiser containing 5% niacinamide on one side and the matching vehicle on the other. The authors reported significant improvements versus control in fine lines and wrinkles, hyperpigmentation spots, texture and red blotchiness; skin yellowing (sallowness), added as a new endpoint in this study, also improved. One author was affiliated with Procter & Gamble. The study supports a claim about that formulation in that population. It does not establish that every niacinamide serum, or a different concentration, gives the same result. Read the trial: PMID 18492135.
Another paper examined pigment transfer in laboratory models and facial pigmentation in Japanese women. Its corresponding author was affiliated with Procter & Gamble. Its clinical arms were a paired comparison in 18 women with hyperpigmentation, who used a 5% niacinamide moisturiser against its vehicle, and 120 women with facial tanning, each assigned to two of three regimens: vehicle, sunscreen, or 2% niacinamide plus sunscreen. After four weeks niacinamide significantly reduced hyperpigmentation and increased skin lightness compared with vehicle alone; no separate comparison is reported for the sunscreen regimen, so those data cannot separate niacinamide from sun protection. The laboratory results did not all point the same way: niacinamide had no effect on purified tyrosinase activity or on melanin production in cultured melanocytes, but it inhibited melanosome transfer to keratinocytes by 35–68% in a coculture model. That is a possible mechanism for a change in appearance, not a guarantee for an untested retail formula. Read the study: PMID 12100180.
Does a higher percentage mean a better product?
These studies do not answer whether 10% outperforms 5%. That would require a direct comparison of finished products under suitable conditions. Vehicle, tolerability and consistent use can all affect the experience. When a brand does not disclose the percentage, the ingredient list cannot supply an exact one; its position in the list is only a rough ordering clue.
What to look for
Check whether a product states its concentration and whether any cited trial tested the finished formula rather than niacinamide in a different cream. Treat phrases such as “clinically proven ingredient” as a prompt to inspect the underlying study, not as proof for the bottle in front of you. Persistent or changing skin concerns warrant individual clinical advice: niacinamide in a cosmetic is a skincare choice, not a treatment.