Hair loss is one of the most common cosmetic conditions. Over 98% of men will experience it to some degree in their lives (1).
Predictably, the market for hair loss treatments is very large. Companies sell a vast range of natural and alternative products that purport to treat it.
One such product is melatonin. This article will cover various topics, including:
- What melatonin is
- Its biological function
- The evidence on its hair growth properties
- Available forms
- Side effects
- If it is the right treatment for you
What Is Melatonin?
Melatonin is a hormone with a wide range of functions. The human body produces it from serotonin, primarily in the pineal gland of the brain (2). From there it is released into the bloodstream and reaches the entire body.
The pineal gland regulates its melatonin production based on visual signals. During the daytime, when there is light, melatonin production decreases. It then increases with nightfall.
In one way or another, melatonin regulates the following:
- Sleep and wakefulness
- Energy metabolism
- Endocrine functions
- Immune system
- Nervous system
- Antioxidant systems and many more
Melatonin binds to specific receptors on the cell membrane. In humans, these two receptors are called MTNR1A and MTNR1B.
Melatonin also affects various bodily functions in ways that do not involve these receptors. This happens through interaction with other proteins as well as its potent antioxidant activity (3).
A Ubiquitous Hormone
Melatonin is ubiquitous in nature. Most animals and plants synthesize it.
Aside from the well-known daily pattern, animals also vary their melatonin production according to season. Researchers now understand that melatonin regulates the seasonal fur growth, molting, and coloration in mammals.
In line with this, scientists have also discovered melatonin receptors in various parts of the animal and human hair follicles. It is also very active in the skin. The skin also acts as a secondary site of melatonin synthesis, in addition to the pineal gland.
Can Melatonin Promote Hair Growth?: In Vitro Results
Like in other mammals, human hair follicles synthesize melatonin. They also have melatonin receptors in abundance. This raises the theoretical possibility that melatonin can be used to promote hair growth and treat hair loss.
Researchers have examined the effects of melatonin on human hair follicles in vitro, in lab cell cultures. The results have been conflicting. One study found melatonin promotes hair follicle cell growth in lower concentrations and has the opposite effect in higher concentrations (4). Other studies have found no effect on hair cell cultures whatsoever (5).
Clinical Studies On Melatonin for Hair Growth
A handful of studies offer clinical data on how melatonin treatment affects human hair growth.
Clinical Studies: #1 – #5
A Swiss pharmaceutical company conducted a series of studies between 2003 and 2006. These looked at melatonin as a potential treatment for male and female androgenetic alopecia (AGA) (6). The topical was a liquid solution with 0.0033% melatonin.
The first study in France examined whether the repeated application of the topical disrupted endogenous melatonin production. The results showed that was not the case. The topical melatonin was well-tolerated.
The second study took place in Milan. Fifteen men and 15 women with AGA applied the solution once daily for a minimum of 90 days. According to the company’s report, there was a “significant reduction in the severity of alopecia” after only 30 days. There was a further reduction after the full 90 days. Unfortunately, it is not clear how this reduction was measured.
The third study was also in Milan. Thirty-five men with early-stage AGA applied the topical daily for six months. The researchers took hair counts in a prescribed area of balding scalp. After six months, 58% of the men had an increase in hair density. The average hair count increase was 42%.
The fourth study was conducted in the United States. It relied on the self-reports of women who used the topical. The women’s hairstylists were also questioned. The results were encouraging, but self-reports are notoriously unreliable.
The final study in the series was a large-scale, multi-center study across 200 dermatology centers in Milan. It recruited 901 balding men and 990 women. According to the medical investigators, two-thirds of patients (66%) improved after 90 days. This assessment was based chiefly on the hair pull test. This is a very simple test where the doctor takes a few strands of hair between his thumb and forefinger and gently but firmly pulls. If an excessive number of strands are removed, this suggests hair loss.
Clinical Study #6
Another study out of Switzerland with some of the same researchers used a different formula. This had 0.1% strength (7). The researchers recruited 40 women with diffuse or androgenetic alopecia. This was a double-blind, placebo-controlled trial. Treatment lasted six months.
Compared to placebo, the melatonin solution significantly increased the percentage of hairs in the anagen growth phase. In other words the percentage of hairs that were actively growing. For women with diffuse alopecia, this increase was significant in the frontal but not the occipital area (in the back of the head). For those with AGA, the reverse was the case; there was a significant anagen increase in the occipital but not frontal area. Overall the results were mixed and difficult to interpret.
Retailers sell melatonin in a wide range of preparations. Consumers have the option to supplement orally in the form of pills, capsules, and tablets. These typically range from one to 10mg in strength. There is also bulk powder and even gummies for children.
Unfortunately, for hair growth, the oral forms are unlikely to be helpful. Men and women with hair loss should turn to topical application of melatonin on the scalp.
The solution used in the Swiss studies is not available for sale. Topical melatonin solutions for hair loss are altogether rare. Some compounding pharmacies offer ready-made solutions. Other companies offer melatonin-based solutions that also combine other active ingredients. The consumer can try these out and evaluate the results.
Side Effects and Counterindications
Doctors generally consider oral melatonin a very safe supplement. Any side effects are typically mild. They may include headache, dizziness, nausea, and drowsiness (8).
If used topically, the evidence suggests the application will not interfere with endogenous melatonin production and distribution. Any side effects will likely be from the vehicle solution rather than the melatonin per se.
If you are taking prescription medication, you should ensure it will not interact with melatonin. Your doctor will be able to advise you on this.
The evidence for melatonin as a hair loss treatment is limited. That melatonin is involved in hair follicle regulation is certain. What we do not yet know is the biological mechanism through which it could act as a hair loss treatment.
When it comes to clinical data, a handful of research reports out of Switzerland are available. Most were not placebo-controlled and were not of the highest quality.
Also, the popularity of melatonin in the hair loss community is low. One way or another, effective treatments tend to become popular among hair loss losers. This happens even in the absence of published academic reports. In the case of melatonin, this did not happen.
All this suggests that melatonin may work, but its efficacy is likely limited. If used for hair loss, it should best be used as an adjunct, not the main treatment. It is a safe, low-cost, natural compound and will do no harm. Whether it will regrow many hairs is a different matter.