Does melatonin only prevent hair loss or also help it grow new hair?

Melatonin is a hormone primarily produced by the pineal gland in response to darkness, regulating sleep-wake cycles. Although its most well-known function is related to the circadian rhythm, recent research has explored its potential in various health fields, including dermatology and trichology. **Among the many areas being studied, hair health has attracted special interest due to melatonin’s possible role in preventing hair loss and potentially stimulating the growth of new hair follicles. ** Hair loss is a common concern that affects millions of people worldwide.

It is estimated that over 50% of men and about 40% of women will experience some degree of hair loss during their lifetime. This has led to a continuous search for effective solutions, from pharmaceutical treatments like minoxidil and finasteride to natural options that could complement these approaches.

Within this latter category, melatonin has emerged as an interesting candidate due to its antioxidant activity and its ability to modulate hair follicle cycles.

The big question is:

Does melatonin only prevent hair loss, or can it actually stimulate new hair growth?

To answer this, we will review the available scientific evidence.

Preventing hair loss or growing new hair? The key difference

Before analyzing the studies, it's crucial to distinguish between the two concepts.

Preventing hair loss means protecting active hair follicles so they do not prematurely enter the resting (telogen) phase and fall out. In contrast, growing new hair means stimulating the formation of new hair follicles or reactivating those that have already closed and stopped producing hair.

The problem is that in the advertising of hair loss products, these two ideas are often mixed. Many treatments are marketed with phrases like "stimulates hair growth" when, in reality, they only prevent accelerated loss. It is important to understand this difference to avoid creating false expectations about the use of melatonin or any other treatment.

Melatonin as a protector of the hair follicle

The hair follicle is a dynamic structure that goes through three main phases: anagen (growth), catagen (transition), and telogen (rest). Various factors can disrupt this natural cycle, accelerating hair loss. Among these, oxidative stress has been identified as a key trigger in androgenetic alopecia and other types of hair loss.

A study conducted in 2012 involved the daily topical application of a melatonin solution directly to the scalp. The research included a population of 40 women with mild to moderate androgenetic alopecia. Over six months, participants used the treatment as part of a consistent routine. Results were evaluated using techniques such as trichoscopy—an imaging method that allows an enlarged view of the scalp and hair follicles—and counting hairs in the anagen phase, which is the active hair growth stage.

The researchers found a significant reduction in hair loss and an improvement in hair density.

However, an important critique of the study is its small sample size, which limits the ability to generalize the results to a broader population. Moreover, the study did not include a direct comparison with other approved treatments, such as minoxidil or finasteride, which would have helped contextualize melatonin’s effectiveness. Another weakness is the lack of long-term follow-up, making it unclear whether the benefits are sustained over time after stopping treatment.

Other studies have reinforced this idea. An article published in 2016 in Experimental Dermatology (Randebrock et al.) indicated that melatonin can also influence the regulation of hormonal receptors in the scalp, reducing the action of androgens, which play a key role in androgenetic alopecia.

Melatonin for growing new hair?

The regeneration of new hair is a biologically more demanding process than simply preventing its loss. While preventing hair loss involves keeping existing follicles active and avoiding their transition to resting or falling phases, stimulating the growth of new hair requires the reactivation of stem cells located at the base of the hair follicle. These stem cells are responsible for initiating the hair growth cycle from scratch, involving a complex network of biochemical signals, interaction with the immune system, and activation of growth factors.

One of the most cited studies on melatonin's potential regenerative role was published in 2018 in the Journal of Pineal Research, led by Slominski and his team. This investigation was conducted in vitro, meaning in laboratory conditions outside the human body, using cultured human dermal papilla cells. These cells are located at the base of the hair follicle and play an essential role in its formation and development. **During the experiment, the cells were exposed to different concentrations of melatonin over a ten-day period. **

The goal was to analyze whether the hormone could induce changes in the expression of certain genes related to hair growth. At the end of the exposure period, there was an increase in the activity of several genes linked to the anagen phase (growth phase), suggesting a possible stimulating effect. However, since the study was not conducted in humans or living animals, its clinical applicability remains limited. Although the results are promising, applying these findings to real-life hair treatments requires further scientific validation.

Another relevant study was published in 2021 in Frontiers in Endocrinology, conducted by Wang and colleagues. In this case, the model was animal-based, specifically mice with hair loss induced by stress. They were given melatonin orally for several weeks. At the end of the treatment, researchers observed a reduction in hair loss and, more notably, a visible increase in follicle regeneration, particularly in areas where hair density had decreased. They measured the length of new hair, follicular density, and other molecular markers related to growth.

Taken together, these studies open the door to future research, but are not sufficient to conclusively state that melatonin alone can generate new hair growth in humans. Robust clinical trials with larger numbers of participants and appropriate duration are still needed to validate its therapeutic use for that purpose.

The regeneration of new hair is a more complex process than simply preventing its loss. To achieve true growth of new follicles or reactivation of inactive ones, stem cells at the base of the follicle must be activated. This process is regulated by multiple biological signals, including growth factors and interactions with the immune system.

Clinical application: what we know so far

Current studies suggest that melatonin may play a protective role in hair health by reducing oxidative stress and prolonging the anagen phase. However, evidence that it can generate significant new hair growth remains limited and is largely based on in vitro or animal studies. Compared to approved treatments like minoxidil or finasteride, melatonin has yet to show comparable results in large-scale clinical trials. Nevertheless, its low side-effect profile and antioxidant potential make it an interesting candidate for future therapeutic combinations.

Conclusion

Melatonin has attracted interest in both clinical and cosmetic contexts due to its antioxidant properties and its potential to intervene in the hair growth cycle. Scientific evidence so far more clearly supports its ability to prevent hair loss, particularly in cases where oxidative stress or hormonal dysfunction compromises follicle health. In this sense, it acts more as a protector than a regenerator. Prevention occurs by maintaining the function of existing follicles and delaying their transition to resting or shedding phases.

On the other hand, the idea that melatonin can grow new hair remains a hypothesis with preliminary evidence. Although in vitro and animal studies show promising effects, these have not yet been robustly replicated in human clinical trials with representative samples and comparable methodologies. Therefore, while its role as an adjuvant in hair care is increasingly accepted, it is still not possible to assert with certainty that melatonin stimulates the creation of new hair follicles or growth in completely bald areas.

This article also highlights the importance of distinguishing between “preventing” and “growing” when discussing hair treatments. Many products use ambiguous advertising language that generates unrealistic expectations. In this context, understanding what has actually been scientifically proven allows people to make informed decisions based on real evidence.

User Experiences

Community feedback on Tressless regarding melatonin use for hair loss reveals a mix of cautious optimism and skepticism, with a number of users reporting personal experiences tied to its use as both a preventive and restorative treatment.

Several users who tried melatonin topically—usually in concentrations around 0.0033% to 0.1%—shared that they observed reduced hair shedding over the course of weeks to a few months. For example, one user applying topical melatonin reported less hair fall within a few weeks of use, particularly when used in combination with microneedling and ketoconazole shampoo. Others found that topical melatonin helped them maintain density but did not noticeably regrow lost hair.

Some community members also discussed using melatonin as a secondary or supportive agent. One post described melatonin as potentially useful when added to a broader routine that includes minoxidil or finasteride, especially for individuals experiencing shedding due to seasonal changes or hormonal imbalances. However, users were quick to point out that melatonin alone was unlikely to regrow significant amounts of hair in cases of advanced androgenic alopecia.

There was also discussion about melatonin being especially helpful for women or those with diffuse thinning. One female user noted that a 0.1% melatonin solution provided noticeable improvement in hair fullness, which she attributed more to its anti-inflammatory properties and DHT-lowering potential than to direct follicular stimulation. Another person said that applying melatonin at night improved scalp condition, which might contribute indirectly to healthier growth.

A few users warned of potential shedding during the early weeks of use, a reaction they suspected might be similar to what occurs when beginning minoxidil. Still, this shedding phase was often followed by stabilization. No one in the thread reported dramatic regrowth from melatonin alone, but its use as a stabilizer or maintenance option received moderate support.

In summary, the community perspective on melatonin suggests that while it may help prevent further loss and improve scalp health, evidence of consistent or significant regrowth is minimal. Its most praised effect appears to be in reducing shedding and supporting overall hair health when used alongside other proven treatments.

References

Fischer, T. W., Trueb, R. M., & Häsler, C. (2012). Melatonin as a potential agent for hair growth. International Journal of Trichology, 4(4), 236-243. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3518413/

Slominski, A., Zmijewski, M. A., Semak, I., Kim, T. K., Janjetovic, Z., & Sweatman, T. (2018). Melatonin and its metabolites regulate hair follicle biology. Journal of Pineal Research, 65(3), e12527. https://pubmed.ncbi.nlm.nih.gov/29893487/

Wang, X., Xu, L., Su, Y., et al. (2021). The effect of melatonin on hair follicle regeneration in stress-induced hair loss. Frontiers in Endocrinology, 12, 671482. https://www.frontiersin.org/articles/10.3389/fendo.2021.671482