NMN for Hair Growth and Grey Hair: What the Evidence Shows
Last reviewed on 12 July 2026. We review our treatment guides every six months to keep them accurate.
NMN (nicotinamide mononucleotide) is a heavily marketed longevity supplement that is also promoted for hair growth and, increasingly, for reversing grey hair. It is worth being clear from the outset about what the evidence does and does not support. The underlying biology is real: NMN is a building block the body uses to make NAD+, a coenzyme that every cell relies on. What is thin is the evidence that taking NMN grows hair on the human scalp or restores colour to grey hair. Most of what exists is laboratory and animal work, plus one small, uncontrolled human study, and there is no large, independent, placebo-controlled trial of the kind that supports minoxidil or finasteride.
This guide sets out what NMN and NAD+ actually are, what the hair-growth and grey-hair research really shows, the current regulatory position, and what genuinely has evidence for hair loss. If you are losing hair and want a reliable, independently maintained overview of the recognised causes and treatments, the NHS hair loss pages are a good starting point. For anything affecting your own hair, it is best to speak to a medical professional who can assess you.
What are NMN and NAD+?
NMN, or nicotinamide mononucleotide, is a small molecule made from vitamin B3 and a sugar. Its importance comes from what the body turns it into: NAD+ (nicotinamide adenine dinucleotide). NAD+ is a coenzyme found in every cell, central to turning food into usable energy and to the machinery that repairs DNA. The body cannot absorb NAD+ well when it is swallowed, so it makes its own from precursors such as NMN. In short, NMN is a precursor and NAD+ is the active molecule it feeds into.
Levels of NAD+ fall as we age, and that decline is the basis of most of the marketing around NMN. The reasoning runs like this: if NAD+ falls with age, and NAD+ powers the cellular processes that keep tissues healthy, then topping it up might slow some of the effects of ageing, including on hair. That is a plausible hypothesis, and it is why NMN is studied at all. It is not, on its own, evidence that an NMN supplement grows hair or changes its colour. The question this page answers is how much of that biology has actually been shown to translate into a real effect on human hair, and the honest answer is: much less than the advertising implies.
Does NMN help hair growth? What the evidence shows
Graded honestly, the hair-growth evidence sits low on the scale. It is mostly laboratory and animal work, with only one small uncontrolled human study. There is no large, independent, placebo-controlled trial establishing that NMN regrows scalp hair or treats pattern hair loss the way minoxidil and finasteride have been shown to. Here is what actually exists, reported for what each study was.
Laboratory and animal studies
The study quoted most often in NMN hair marketing is a 2024 laboratory paper. It is worth reading carefully, because two details tend to get lost. First, its human part was done in a dish: cultured human dermal papilla cells, the cells at the base of the follicle, were exposed to DHT (the hormone that drives pattern hair loss) and then to NMN, which reduced markers of inflammation and oxidative stress and shifted several growth-related signals in a favourable direction. Second, the live-animal part used NMN applied to the skin of shaved mice, not an oral supplement in people, and reported faster regrowth than in untreated mice. One of the study's authors was employed by a supplement company. This is a genuine and interesting mechanistic result, but it is a finding in cells and in mice, not evidence that swallowing NMN grows hair on a person's head.
Human studies
Human data on NMN for hair are very limited. The closest is a 2025 study of oral NMN in middle-aged women, which reported improvements in some measures of hair growth and cuticle condition. It is important to be clear about what this study was: 15 women, everyone took NMN, there was no placebo group, it ran for three months, and it was funded by a company that sells the ingredient, with several of its authors employed by that company. The authors themselves note that, without a placebo group, the results cannot tell you whether NMN caused the changes rather than the season, expectation or normal variation. That is not a criticism smuggled in from outside; it is the study's own conclusion. So the honest summary is that one small, uncontrolled, industry-funded pilot has reported encouraging signs, and that this is a long way from proof.
This also puts the 'before and after' photos you will see online in context. A single arm of before-and-after pictures, with no comparison group and no blinding, cannot separate a real effect from timing, better grooming, or the simple fact that people photograph their hair when they are hopeful about it. It is exactly the kind of evidence that controlled trials exist to replace.
Can NMN reverse grey hair?
Reversing grey hair is one of the most searched claims about NMN, and it is where the gap between marketing and evidence is widest. Grey hair happens when the pigment-producing cells in the follicle gradually fail: they make less pigment, and over time the follicle's reserve of pigment stem cells becomes depleted. Oxidative stress, the same kind of cellular wear that NAD+ biology is concerned with, is thought to be an important driver. Crucially, a detailed review of the biology of human greying concludes that once that stem-cell reserve is exhausted, greying is largely irreversible. That is the theoretical hook the marketing hangs on: NMN supports NAD+ and NAD+ helps cells cope with oxidative stress, so perhaps it could protect the pigment cells. But a plausible mechanism is not a demonstrated effect. There is no good human evidence that NMN restores colour to hair that has already gone grey, and the 'before and after' images circulated online are testimonials, not controlled data. If keeping your natural colour longer matters to you, the honest position today is that no supplement, NMN included, has been shown to reverse human greying.
Is NMN safe, and its regulatory status
In the short human studies done so far, NMN has generally been reported as well tolerated, with only mild effects such as occasional digestive upset or headache. The important caveat is that these studies are mostly small and short, so good long-term safety data are limited, and 'well tolerated in a three-month trial' is not the same as 'proven safe over years'. As with any supplement, if you take other medicines or have a health condition, it is worth checking with a pharmacist or doctor first.
The regulatory position on NMN has also been unsettled and is worth knowing. In the United States, the FDA said in November 2022 that NMN could not be sold as a dietary supplement, because it had by then been investigated as a drug. In September 2025 the FDA reversed that position, concluding that NMN is not excluded from the definition of a dietary supplement, though companies must still notify it as a new dietary ingredient. In the UK, NMN is sold as a food supplement. This is an area that has changed more than once, so treat the position as accurate at the time of this review rather than fixed.
If you are having a hair transplant or any other surgery, tell your surgeon and clinic about every supplement you take, including NMN, and follow the pre-operative instructions they give you. Clinics differ in what they ask you to stop and when, so the safe course is to disclose it and follow your own clinic's guidance rather than a general rule from an article.
What actually has evidence for hair loss
For pattern hair loss, the treatments with a genuine evidence base are minoxidil, applied to the scalp, and, for men, finasteride, a tablet that lowers DHT. Neither is a cure, both work only for as long as they are used, and finasteride is a decision to make with a doctor because of its side-effect profile and because it is not suitable for women. None of this makes NMN harmful, but it does put it in perspective: it is not in the same category as treatments that have been through proper trials. Whether any treatment is right for you is a question for a medical professional who can assess you.
The bottom line
NMN rests on real, well-documented biology: it feeds NAD+, which every cell needs, and NAD+ falls with age. What is missing is the step that matters most: good, independent human evidence that taking NMN grows scalp hair, slows pattern hair loss, or reverses grey hair. On the current evidence it is best seen as an interesting longevity supplement with a plausible but unproven story for hair, not a treatment. If your hair loss or greying is bothering you, the most useful next step is an assessment by a medical professional who can tell you what is actually driving it and which options are worth your time and money.
Frequently asked questions
Does NMN help hair growth?
There is no strong human evidence that it does. The encouraging findings are mostly from laboratory cells and from NMN applied to the skin of mice, and the one human study to date was small, uncontrolled and funded by a company that sells the ingredient. No large, independent, placebo-controlled trial has shown that NMN grows scalp hair, so it should not be relied on as a proven treatment for hair loss.
Can NMN reverse grey hair?
There is no good evidence that it can. Grey hair is the result of the follicle's pigment cells failing and its pigment stem-cell reserve becoming depleted, and once that reserve is exhausted greying is largely irreversible. NMN has a plausible theoretical link through NAD+ and oxidative stress, but a plausible mechanism is not a demonstrated effect, and the before-and-after photos online are testimonials rather than controlled evidence. No supplement, NMN included, has been shown to restore colour to grey human hair.
Can NMN cause hair loss?
There is no evidence that NMN causes hair loss. In the short studies done so far it has generally been well tolerated. As with any supplement, long-term data are limited, so if you notice increased shedding after starting anything new it is worth speaking to a doctor, who can look for the more common causes of hair loss rather than assuming a supplement is to blame.
Is NMN the same as NAD+?
No, but they are closely linked. NMN is a precursor: the body absorbs it and uses it to make NAD+, the coenzyme that actually powers cellular energy and DNA repair. You cannot usefully take NAD+ directly by mouth, which is why supplements provide a precursor such as NMN instead. When people take NMN for its supposed anti-ageing effects, the goal is to raise NAD+.
What actually works for hair loss instead?
For pattern hair loss, the treatments with a real evidence base are minoxidil for men and women and finasteride for men, both of which have been through controlled trials. They are not cures and only work while they are used, and finasteride is a decision to make with a doctor. Where hair has already been lost, a hair transplant is the surgical option. The right step is an assessment by a medical professional who can tell you what is driving your hair loss and which options fit your situation.
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