Niacin for Hair: What the Research Shows
Niacin (vitamin B3) has mixed hair evidence, and the form matters. A 6-month pilot in women found that topical niacin derivatives increased hair fullness, while a 2020 analysis concluded that topical niacinamide does not stimulate hair growth based on existing evidence. Oral niacin has its own side effects, including flushing.
Here's what each study found and what to know before taking niacin.
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Key Takeaways
- In a 6-month, placebo-controlled pilot of 60 women with female pattern hair loss, topical niacin derivatives (octyl and tetradecyl nicotinate) significantly increased hair fullness compared with placebo.
- A 2020 paper found niacinamide could not stimulate VEGF synthesis in a lab assay and concluded it does not stimulate hair growth based on existing evidence.
- Oral niacin and nicotinamide are linked to side effects including stomach upset, liver dysfunction, flushing and rash, and these are dose-dependent.
- We found no trial of oral niacin for hair growth.
What Is Niacin?
Niacin is a form of vitamin B3, along with nicotinamide (niacinamide). Different forms behave differently, so a result for one doesn't apply to another.
Does Niacin Help Hair?
It depends on the form. A pilot of topical niacin derivatives was positive; topical niacinamide was not supported; and oral niacin has not been tested for hair.
Using Niacin Carefully
- Match the form to the evidence. The positive pilot used topical nicotinate esters.
- Don't megadose. Side effects are dose-dependent.
- Ask your doctor before taking oral niacin, especially with a liver or kidney condition.
What The Research Shows
Topical Niacin Derivatives
Sixty women with Ludwig type I to III female pattern hair loss were randomized to a topical niacin derivative (40 active, 20 placebo) for 6 months. Blinded photographic analysis showed a statistically significant increase in hair fullness versus placebo (P = 0.04). The authors called it a pilot and said it warrants further study (Draelos et al., 2005).
Topical Niacinamide
A letter tested whether niacinamide stimulates VEGF synthesis in vitro, found it did not across a broad range of doses, and concluded that topical niacinamide does not stimulate hair growth based on existing evidence (Oblong et al., 2020).
Oral Niacin Side Effects
An overview of 14 reviews found oral niacin and nicotinamide were associated with adverse effects including stomach upset, liver dysfunction, flushing, skin rash and fatigue. Nicotinamide had a lower incidence of side effects than niacin, effects were more common at higher doses, and most diminished or resolved when the dose was reduced or stopped (Young & Gazzard, 2025).
See also: Turmeric for Hair and Scalp: What the Research Shows · Melatonin for Hair Growth: What the Research Shows
Frequently Asked Questions
Does niacin help hair growth?
A pilot found topical niacin derivatives increased hair fullness in women, but topical niacinamide wasn't supported and oral niacin hasn't been tested for hair.
Is niacin safe?
Oral niacin can cause flushing, stomach upset and liver effects, and these are dose-dependent. Talk to your doctor first.
Is niacinamide the same as niacin?
No. They are different forms of vitamin B3 and have different effects and side-effect profiles.
References
- Draelos ZD, Jacobson EL, Kim H, et al. A pilot study evaluating the efficacy of topically applied niacin derivatives for treatment of female pattern alopecia. J Cosmet Dermatol. 2005. PubMed
- Oblong JE, Peplow AW, Hartman SM, et al. Topical niacinamide does not stimulate hair growth based on the existing body of evidence. Int J Cosmet Sci. 2020. PubMed
- Young SL, Gazzard G. The adverse effects of oral niacin/nicotinamide - an overview of reviews. Eye (Lond). 2025. PubMed
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