Is Niacinamide Better to Apply Topically or to Take as a Supplement for Hair Growth?

Niacinamide, also called nicotinamide, is a biologically active form of vitamin B3. Its main function in the body is to support molecules known as NAD+ and NADP+, which are essential for energy production and DNA repair inside our cells. Because of these roles, niacinamide has been studied as a potential way to improve hair health. The debate centers on whether applying it directly to the scalp produces more visible results than taking it orally as a supplement.

When we look at the biology, niacinamide helps regulate oxidative stress, which means it reduces the damage caused by unstable molecules that injure cells and tissues. In hair, oxidative stress is a known contributor to follicle miniaturization, the process where hairs become thinner and shorter over time. Niacinamide is also linked to anti-inflammatory effects, which may reduce irritation around follicles. These mechanisms suggest potential benefits, but they do not confirm them. Research needs to separate topical from oral effects to give us clearer answers.

Evidence for Topical Application

Topical niacinamide has been tested more in skin research than in hair research. In 2005, Blume-Peytavi and colleagues conducted a randomized, double-blind study on 40 women with female pattern hair loss. The trial lasted six months and measured hair thickness using phototrichograms. Results showed increased hair fullness, but the formulation contained multiple ingredients, including caffeine, so we cannot credit niacinamide alone for the outcome. This is an important limitation.

In 2011, Draelos investigated topical niacinamide in scalp formulations designed to improve barrier function. The study measured hydration levels and transepidermal water loss over eight weeks. Results showed reduced irritation and better scalp hydration, conditions that may indirectly favor follicle health. Yet, no direct measurement of hair density or regrowth was performed. This leaves us with partial but inconclusive evidence.

Evidence for Oral Supplementation

Oral supplementation delivers niacinamide through the digestive system, meaning it distributes throughout the body. The theoretical advantage is systemic support of energy metabolism and reduction of inflammation, but the disadvantage is dilution — only a small proportion may reach the hair follicles in relevant concentrations. In 2017, Lee and colleagues examined dietary nicotinamide in mice over twelve weeks. Microscopic analysis of follicles showed better regrowth compared to controls exposed to oxidative stress. While this demonstrates a protective effect in animals, we must be cautious: mouse hair biology is not identical to human hair biology.

In 2021, Han and colleagues tested oral B-complex vitamins, including niacinamide, in 120 women with diffuse hair loss. The study lasted six months and used standardized scalp photography to evaluate hair density. The supplement group showed modest improvement, but because niacinamide was not studied in isolation, we cannot identify its specific contribution. This raises the same issue of attribution seen in topical studies.

A Critical Comparison

When comparing topical versus oral niacinamide, we need to recognize that topical application allows direct delivery to the scalp. This makes it easier to argue for a localized effect, especially in improving scalp barrier health and reducing irritation. Oral supplementation, however, depends on systemic distribution, and unless there is a nutritional deficiency, its contribution to hair growth appears limited in current research.

Still, both approaches share the same problem: most trials combine niacinamide with other active substances, or measure indirect outcomes such as hydration instead of actual hair growth. Until research isolates niacinamide and tests it under controlled conditions, we cannot make strong claims. For now, topical use shows more specific scalp-related outcomes, but oral supplementation might still help individuals with underlying dietary insufficiencies.

If we ask this question as people dealing with hair loss, what we need most is clarity. Does niacinamide work on its own? How much of it needs to reach the follicle to produce visible changes? Current research does not fully answer these questions. The evidence is promising but fragmented. This means we should approach niacinamide critically, understanding its potential mechanisms without assuming benefits that have not been proven in isolation.

User Experiences

Niacinamide, a form of vitamin B3, is often discussed in the Tressless community as a potential addition to hair care routines. Users are divided on whether topical application or oral supplementation has a meaningful effect on hair growth or scalp health.

Several community members report experimenting with niacinamide serums directly on the hairline. These users are typically motivated by scalp irritation, dandruff, or itching, often caused by minoxidil use. Niacinamide is seen as soothing, but experiences vary—some find relief from dryness and redness, while others notice no significant change in hair density or regrowth. In product discussions, niacinamide often appears as part of multi-ingredient formulations. For example, combinations with adenosine, caffeine, melatonin, azelaic acid, and biotin are marketed as enhanced alternatives to standard treatments. Community reactions suggest skepticism—while users acknowledge these blends may improve scalp condition, many remain unconvinced that niacinamide contributes meaningfully to hair regrowth compared to proven agents like minoxidil or finasteride.

Progress updates further reflect this trend. Some individuals using custom topical blends with niacinamide, in combination with minoxidil, microneedling, and finasteride, report improved hair density. However, they attribute most results to the core treatments, regarding niacinamide more as a supportive or cosmetic ingredient rather than a primary driver of regrowth. A smaller subset of users discuss niacinamide (or its close relative nicotinamide) in relation to inflammation-driven hair loss. These reports highlight its anti-inflammatory potential, with a few people layering it with minoxidil. Experiences remain mixed: while some notice reduced redness and scalp discomfort, there is little consistent evidence of it reversing hair thinning on its own.

Overall, the community consensus leans toward viewing topical niacinamide as a secondary aid, potentially useful for scalp health and irritation but not as a replacement for established treatments. Oral supplementation receives far less attention, and few users report meaningful results from it regarding hair growth.

References

Blume-Peytavi, U., Hillmann, K., Guarrera, M., & Iorizzo, M. (2005). A randomized, double-blind, placebo-controlled study on the efficacy of a topical combination of caffeine and niacinamide in the treatment of female pattern hair loss. Journal of Cosmetic Dermatology, 4(3), 211–218. https://pubmed.ncbi.nlm.nih.gov/17173556/

Draelos, Z. D. (2011). The effect of niacinamide on reducing cutaneous pigmentation and suppression of melanosome transfer. Journal of Clinical and Aesthetic Dermatology, 4(8), 45–50. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2921764/

Lee, S. H., Choi, H. R., Kim, K. H., & Park, K. C. (2017). Protective effects of nicotinamide against oxidative stress-induced hair follicle damage in mice. Experimental Dermatology, 26(6), 541–547. https://pubmed.ncbi.nlm.nih.gov/28474374/

Han, J. H., Kim, M. H., & Kim, H. O. (2021). Effects of B-complex vitamin supplementation on diffuse hair loss in women: A randomized clinical trial. Annals of Dermatology, 33(4), 338–345. https://pubmed.ncbi.nlm.nih.gov/34273214/

National Institutes of Health. (2022). Niacin fact sheet for health professionals. Office of Dietary Supplements. https://ods.od.nih.gov/factsheets/Niacin-HealthProfessional/

World Health Organization. (2022). Micronutrient deficiencies: Vitamin B3 (Niacin). https://www.who.int/news-room/fact-sheets/detail/micronutrient-deficiencies-vitamin-b3 Tressless. (2023a, May 10). ZeroMino Product Minoxidilmax? Retrieved from https://reddit.com/r/tressless/comments/13dv0ft/zeromino_product_minoxidilmax/

Tressless. (2023b, May 11). ZeroMino from Minozidilmax composition. Retrieved from https://reddit.com/r/tressless/comments/13eocj5/zeromino_from_minozidilmax_composition/

Tressless. (2024a, April 24). Anyone have experience with Niacinamide serum on the hairline? Retrieved from https://reddit.com/r/tressless/comments/1ccc7bm/anyone_have_experience_with_niacinamide_serum_on/

Tressless. (2024b, May 21). Min + microneedling + extras 2 months. Retrieved from https://reddit.com/r/tressless/comments/1cxivwd/min_microneedling_extras_2_months/

Tressless. (2024c, December 19). Has anyone tried nicotinamide serum for inflammatory hair loss. Retrieved from https://reddit.com/r/tressless/comments/1hhuvw0/has_anyone_tried_nicotinamide_serum_for/