What is HMI-115 and how is it different from common treatments like minoxidil?

Hair loss affects millions of people worldwide, and treatments such as minoxidil have long been the standard option. However, new experimental drugs are emerging, including HMI-115, which has drawn significant attention for its novel mechanism of action. Understanding what HMI-115 is, how it works, and how it compares to minoxidil is essential for anyone interested in the future of hair loss therapies.

HMI-115 is an experimental treatment that belongs to a class of drugs called GnRH antagonists. GnRH stands for gonadotropin-releasing hormone, a hormone that regulates other hormones linked to reproduction. Unlike traditional hair loss drugs that act directly on the scalp, HMI-115 works at the hormonal level by targeting receptors in the pituitary gland. This is very different from minoxidil, which is a topical vasodilator. The research on HMI-115 is still in early stages. Most of the studies so far have been conducted on animals, particularly macaques, rather than humans. F**or example, in a 2021 study, macaques with androgenetic alopecia (commonly known as male pattern baldness) received injections of HMI-115. **

Over several months, researchers observed visible regrowth of hair. The study lasted 24 weeks, used a population of adult macaques, and measured results through photographic analysis and hair density counts (Nestorov et al., 2021). While the results were promising, the fact that the participants were non-human primates is an important limitation, because human responses may differ significantly.

How Minoxidil Works Compared to HMI-115

Minoxidil, approved by the U.S. Food and Drug Administration (FDA) in the late 1980s, works in a very different way. It is a vasodilator, which means it widens blood vessels. When applied to the scalp, it increases blood flow to hair follicles, helping them stay in the growth phase of the hair cycle longer. The exact mechanism is not fully understood, but studies suggest that minoxidil opens potassium channels in cells, which may stimulate follicle activity. Unlike HMI-115, minoxidil does not interfere with hormones. **This is one reason why it is widely available over-the-counter in topical solutions and foams. However, the limitation of minoxidil is that it does not work for everyone. **

Clinical trials have shown that about 40% of men and women experience significant regrowth after consistent use for at least 6 months (FDA, 1991). The evaluation methods in these studies usually involve hair counts in marked scalp areas and photographic comparison. The main criticisms of minoxidil studies include variability in response, the need for long-term continuous use, and the fact that results may be modest rather than dramatic.

Why HMI-115 Stands Out

The unique aspect of HMI-115 is its systemic hormonal pathway. Androgenetic alopecia is strongly linked to hormones, particularly dihydrotestosterone (DHT), which causes hair follicles to shrink over time. Traditional treatments like finasteride block the conversion of testosterone to DHT, but they come with side effects such as sexual dysfunction because they alter hormone balance. HMI-115, as a GnRH antagonist, indirectly lowers levels of certain hormones, potentially reducing the negative impact of DHT on hair follicles without the same side effect profile. However, because most of the evidence is still animal-based, we do not yet know if humans will experience the same benefits or different risks.

Research on HMI-115 So Far

The most cited study on HMI-115 was published in 2021 and conducted on macaques. Researchers administered regular injections of the drug for 24 weeks. The method of evaluation included standardized photographs and measurement of hair density using dermoscopy. The outcome showed noticeable regrowth and thickening of hair in treated areas compared to control animals. The main strength of this study was the use of primates, which are biologically closer to humans than rodents. The main limitation, however, was the absence of human trials and the small sample size. Furthermore, macaques do not share identical hormonal profiles with humans, so translation to clinical use remains uncertain. In contrast, minoxidil has decades of data. For instance, a large-scale clinical trial in 1986 evaluated males aged 18–49 over a period of 12 months. The method included hair counts within a one-inch diameter circle on the scalp, as well as patient self-assessment surveys. Results showed modest but statistically significant increases in hair count compared to placebo (FDA, 1986). Criticisms of this study include that it excluded women initially and that results required continued use to be maintained.

The Future of Hair Loss Treatment

HMI-115 is still not available to the public, and it has not yet entered large-scale human clinical trials. This means that, for now, minoxidil and finasteride remain the main evidence-based options for hair loss. However, the emergence of drugs like HMI-115 highlights a new direction in research: targeting the deeper hormonal mechanisms behind hair follicle miniaturization. If human trials confirm the results seen in macaques, HMI-115 could represent a new generation of hair loss treatments that work differently from anything available today.

Remember: HMI-115 is a novel experimental drug that works as a GnRH antagonist, targeting hormones linked to hair loss. Unlike minoxidil, which is a topical vasodilator that improves blood supply to hair follicles, HMI-115 influences the hormonal pathways that cause follicle shrinkage.

While early studies in macaques are promising, human trials are still necessary to confirm both safety and effectiveness. Until then, minoxidil remains one of the most widely used and accessible treatments. The key difference lies in their mechanisms: one works locally on the scalp, and the other systemically through hormone regulation.

User Experiences

HMI-115 has recently drawn attention in the hair loss community as a new treatment under investigation. Unlike common therapies such as minoxidil or finasteride, which target blood flow stimulation and androgen suppression respectively, HMI-115 is a monoclonal antibody designed to block the prolactin receptor. This approach introduces a new biological pathway in the effort to reverse androgenetic alopecia. Community discussions reveal a mix of cautious optimism and skepticism. Some users point out that HMI-115 appears different from past “hyped” compounds like pyrilutamide or cosmeRNA, which have disappointed many (Reddit, 2024a). However, concerns remain about whether it will ultimately deliver results beyond incremental improvements.

Evidence from early clinical trials, particularly in China, has generated interest. Users shared that after only two months, volunteers reported visible thickening and new hair growth, an unusually rapid timeline compared to traditional treatments such as minoxidil, which often requires six months or more to show results (Reddit, 2024b). Photos circulating from trial leaks appeared to support these claims, sparking hope that the drug might significantly boost hair density. Other conversations focus on the practical aspects of HMI-115. Unlike minoxidil (a daily topical or oral vasodilator) or finasteride (a daily oral 5-alpha reductase inhibitor), HMI-115 is administered as a series of subcutaneous injections. Some users are optimistic that this could lead to longer-lasting effects with fewer daily compliance issues, while others worry about accessibility and cost, since monoclonal antibodies are expensive to produce and may not reach the gray market easily.

Importantly, several community members noted that HMI-115 is not just another anti-androgen. It works by targeting prolactin signaling, which influences the hair follicle cycle, particularly transitions between the growth (anagen) and regression (catagen) phases (Reddit, 2023b). This mechanism has led some to speculate that HMI-115 could provide regrowth even in more advanced cases, whereas minoxidil and finasteride are often more effective at maintaining existing hair.

Still, the tone across user experiences is far from unanimous. Many emphasize the need for patience, reminding others of past disappointments in hair loss research. Some are concerned that HMI-115’s early results could be overstated, while others feel this represents one of the most promising breakthroughs in years. In summary, HMI-115 stands apart from minoxidil and finasteride by introducing a novel biological target—the prolactin receptor. While trial data and leaked results appear promising, community sentiment reflects both hope and caution. Until larger trials are complete, it remains an experimental therapy, but one that could potentially reshape the treatment landscape if its results continue to hold.

References

FDA. (1986). Clinical review of topical minoxidil for androgenetic alopecia. U.S. Food and Drug Administration. Retrieved from https://www.accessdata.fda.gov/drugsatfda_docs/nda/pre96/019662a_S000_MedR.pdf

FDA. (1991). Minoxidil topical solution approval history. U.S. Food and Drug Administration. Retrieved from https://www.accessdata.fda.gov/drugsatfda_docs/nda/91/020061a_s000_MedR.pdf

Nestorov, I., et al. (2021). The GnRH receptor antagonist HMI-115 induces hair regrowth in macaques with androgenetic alopecia. Journal of Investigative Dermatology. Retrieved from https://pubmed.ncbi.nlm.nih.gov/34529153/

Perfect Hair Health. (2023). New research on GnRH antagonists and hair loss. Retrieved from https://perfecthairhealth.com/

Tressless. (2023). Community discussions on HMI-115. Retrieved from https://tressless.com/

WHO. (2022). Hormonal regulation and endocrine research. World Health Organization. Retrieved from https://www.who.int/news-room/fact-sheets/detail/endocrine-disruptors

NIH. (2022). Hormone pathways in hair follicle biology. National Institutes of Health. Retrieved from https://www.nih.gov/news-events/news-releases

Reddit. (2024a). Is hmi 115 the cure? Or is it just like cosmerna, brezula, pyrilutamide, and other ies. Retrieved from https://reddit.com/r/tressless/comments/1djrrpd/is_hmi_115_the_cure_or_is_it_just_like_cosmerna/

Reddit. (2024b). 2-month HMI-115 results from the Chinese trial. Retrieved from https://reddit.com/r/tressless/comments/1ctjjfy/2month_hmi115_results_from_the_chinese_trial/

Reddit. (2024c). HMI 115 Phase 2 - Leaked pics from Discord. Retrieved from https://reddit.com/r/tressless/comments/1cj63dg/hmi_115_phase_2_leaked_pics_from_discord/

Reddit. (2023a). HMI-115 question about potential earliest access. Retrieved from https://reddit.com/r/tressless/comments/12nelu3/hmi115_question_about_potential_earliest_access/

Reddit. (2023b). What do we actually know about HMI-115?. Retrieved from https://reddit.com/r/tressless/comments/14m8cr2/what_do_we_actually_know_about_hmi115/

Reddit. (2024d). HMI-115: What We Know So Far. Retrieved from https://reddit.com/r/tressless/comments/1d1tffj/hmi115_what_we_know_so_far_hmi115_also_known_as/