Encyclopedia · other
Niacinamide
Niacinamide is a safe, cheap vitamin B3 form found in many hair serums, but no trial shows it grows hair on its own.
What it is
Niacinamide (nicotinamide) is the amide form of vitamin B3. In cosmetics it is a skin and hair conditioning ingredient used from trace levels up to about 3% in leave-on products (CIR 2005). It is distinct from the nicotinate esters (see methyl nicotinate) and from niacin, which flushes the skin. It is available in the US, EU and UK as a cosmetic ingredient and as a supplement.
How it works
The popular claim is that niacinamide raises VEGF and blood flow around the follicle. A 2020 in-vitro test by Procter & Gamble scientists found it could not stimulate VEGF synthesis across a broad dose range (Oblong 2020). That is a short letter from a company that sells competing products, so treat it as a counterweight rather than final proof. Other proposed roles are scalp barrier support and NAD+ supply. A related compound, NMN, protected cultured dermal papilla cells and helped DHT-treated mice, but that is cell and animal data only (Xu 2024).
What the studies show
- A 24-week Procter & Gamble trial of a shampoo and leave-on regimen containing niacinamide with piroctone olamine, zinc pyrithione, panthenol and caffeine reduced shedding and raised hair count versus placebo. Niacinamide's share cannot be isolated, and the trial was industry-funded. Davis 2021
- In 60 women, octyl and tetradecyl nicotinate, which are niacin derivatives and not niacinamide, improved hair fullness versus placebo over 6 months (P=0.04). Co-authors came from a niacin-ingredient developer. Draelos 2005
- Niacinamide did not stimulate VEGF in cultured cells. Oblong 2020
- NMN, a NAD+ precursor, countered DHT effects in cells and mice. It is not niacinamide. Xu 2024
How it's used in studies
Niacinamide was one component in the Procter & Gamble regimen and the dose was not reported in the abstract. Cosmetic use runs up to roughly 3% in leave-on products.
Side effects and safety
The Cosmetic Ingredient Review panel judged niacinamide and niacin safe as used in cosmetics, with no significant irritation, sensitization or photosensitization in clinical testing at up to 5% (CIR 2005). Niacin, not niacinamide, is the form that flushes.
Bottom line
For hair growth the evidence is weak: no trial isolates niacinamide as a hair-growth active. It is reasonable for scalp barrier and oiliness in a formula you like, but do not pay extra for it as a growth ingredient. Proven options are minoxidil and finasteride.
Studies 5
Cosmetic Ingredient Review Expert Panel. Final report of the safety assessment of niacinamide and niacin. Int J Toxicol. 2005
Tested: niacinamide and niacin in cosmetics
Result: Judged safe as used in cosmetics, with no significant irritation, sensitization or photosensitization in clinical testing at up to 5%.
Read the study ↗Oblong JE et al. Topical niacinamide does not stimulate hair growth based on the existing body of evidence. Int J Cosmet Sci. 2020
Tested: niacinamide across a broad dose range
Result: Niacinamide did not stimulate VEGF synthesis. A short letter by Procter & Gamble scientists.
Read the study ↗Davis MG et al. Scalp application of antioxidants improves scalp condition and reduces hair shedding in a 24-week randomized, double-blind, placebo-controlled clinical trial. Int J Cosmet Sci. 2021
Tested: shampoo plus leave-on with piroctone olamine, zinc pyrithione, niacinamide, panthenol and caffeine vs placebo
Result: Shedding fell and total hair count rose versus placebo; the share of each ingredient cannot be separated. Funded by Procter & Gamble.
Read the study ↗Draelos ZD et al. A pilot study evaluating the efficacy of topically applied niacin derivatives for treatment of female pattern alopecia. J Cosmet Dermatol. 2005
Tested: octyl and tetradecyl nicotinate vs placebo
Result: Hair fullness improved versus placebo (P=0.04). Niacin derivatives, not niacinamide or methyl nicotinate; co-authors from the ingredient developer.
Read the study ↗Xu C et al. Beta-nicotinamide mononucleotide promotes cell proliferation and hair growth by reducing oxidative stress. Molecules. 2024
Tested: nicotinamide mononucleotide (NMN)
Result: NMN protected cells from oxidative stress and helped DHT-treated mice; it is a related compound, not niacinamide.
Read the study ↗Related
- Caffeine (topical)Caffeine in shampoos and leave-on liquids clearly stimulates hair follicles in the lab, but the human trials are small, mostly industry-run and mostly on blends.
- Methyl nicotinateMethyl nicotinate makes skin flush and tingle by widening small blood vessels, but no controlled trial shows it grows hair.
- BiotinA B vitamin that restores hair only in the rare people who are deficient, and that can scramble thyroid and heart blood tests at the doses sold for hair.