Is Metformin Used Topically for Hair Loss, or Only as an Oral Tablet?

Metformin, a drug widely known for treating type 2 diabetes, has recently become the subject of speculation in the field of hair loss research. The question often arises: can it be used topically on the scalp to promote hair growth, or is it limited to oral use? While the oral form remains the only FDA-approved option, emerging evidence suggests that topical metformin is being experimentally tested for hair disorders, though the data remains limited and inconclusive.

What Metformin Does — And Why Researchers Are Interested in the Scalp

Metformin primarily acts on the liver and peripheral tissues to lower blood sugar levels. It reduces hepatic glucose production and improves the body’s sensitivity to insulin. Beyond its metabolic role, scientists have discovered that metformin activates a cellular pathway known as AMP-activated protein kinase (AMPK). AMPK is a key regulator of energy balance in cells, and its activation can influence inflammation, fibrosis (the formation of scar-like tissue), and cellular stress — all processes that are relevant to hair follicle health.

Hair follicles are metabolically active structures, requiring high energy for continuous cell division and hair fiber production. Chronic inflammation, fibrosis, and hormonal imbalances can disrupt this cycle and cause various types of hair loss, from androgenetic alopecia (pattern baldness) to cicatricial (scarring) alopecias. Because metformin influences the same cellular stress and inflammatory pathways that damage follicles, researchers began testing whether it might restore follicular function when applied directly to the scalp.

From Diabetes to Dermatology: How the Research Started

The earliest clues came from laboratory and animal studies. In 2021, researchers in Japan exposed dermal papilla cells — the specialized cells at the base of hair follicles — to metformin in a three-dimensional culture system. Over several days, they observed that metformin increased the expression of genes associated with hair induction and follicle regeneration (Hamada et al., 2021). The study was conducted in vitro, meaning outside the body, in a controlled environment of cultured cells. While promising, such experiments can only show biological potential, not real-world results.

In 2025, a team of scientists in China tested a topical metformin nanosystem in mice. Over several weeks, mice treated with metformin-loaded nanoparticles showed accelerated hair growth compared to untreated animals (Zhang et al., 2025). The researchers evaluated regrowth through photographic assessment and microscopic examination of new follicles. Yet, despite these results, mouse skin differs substantially from human scalp tissue, and animal models often exaggerate potential benefits.

What Human Studies Tell Us (and What They Don’t)

Human evidence for topical metformin is sparse and mainly composed of case reports or small pilot studies. In 2019, dermatologists documented two women with central centrifugal cicatricial alopecia (CCCA) — a scarring form of hair loss — who experienced partial regrowth after applying a 10% compounded topical metformin cream for several months (Ross et al., 2019). The evaluation relied on clinical observation and photographic comparison, and both patients were using other treatments, such as corticosteroids. Without controls, it is impossible to attribute results solely to metformin.

In 2024, another case report described topical metformin as an adjuvant (additional) treatment alongside oral antibiotics and topical minoxidil. After ten months, the patient exhibited mild improvement in hair density (Williams & Kirby, 2024). This again highlights the difficulty of isolating effects when several therapies are used simultaneously.

A more structured attempt came from a 2024 observational study published in JAMA Dermatology, which examined nine patients with CCCA treated with low-dose topical metformin. After six months, participants reported reduced scalp pain and itching, and biopsy samples revealed decreased inflammatory and fibrotic gene expression (Bao et al., 2024). However, without a randomized control group, causality cannot be confirmed. The small sample size and subjective outcome measures limit its reliability.

Overall, human data remain preliminary. The number of participants is low, treatment durations are short, and evaluation methods vary. While early findings suggest metformin may improve inflammation and fibrosis in scalp tissue, no large-scale or blinded clinical trial has yet confirmed its effectiveness for hair regrowth.

Oral Metformin: Does It Influence Hair?

Since oral metformin is widely used for metabolic disorders, it has indirectly been studied in relation to hair health. In individuals with polycystic ovary syndrome (PCOS), who often experience hormonal imbalance and hair thinning, oral metformin can lower androgen levels and improve insulin sensitivity, which in turn may reduce androgen-related hair loss. However, this effect is indirect and inconsistent across studies. The FDA label for metformin does not include hair loss or hair regrowth as recognized side effects or indications. Large clinical datasets have not shown metformin to cause or reverse baldness.

In other words, oral metformin may help certain patients indirectly through hormonal regulation, but it is not a targeted hair loss therapy.

The Current Scientific Position

As of today, metformin is used almost exclusively in oral form, and its topical use for hair loss remains experimental. Laboratory and mouse studies have provided a biological rationale, but human evidence is not yet strong enough to support its inclusion in dermatological practice. There are no FDA-approved topical metformin formulations for hair loss, and most reports stem from off-label compounding or individual trials. The safety of long-term topical use — particularly the risk of systemic absorption and potential metabolic effects — also remains insufficiently explored.

What We Need to Know Moving Forward

For those of us following this research, the key question is not whether topical metformin can theoretically influence hair growth, but whether it can do so safely, reproducibly, and better than existing options like minoxidil or finasteride. To answer this, randomized, double-blind clinical trials must evaluate its efficacy, optimal concentration, vehicle formulation, duration of use, and systemic absorption profile. Until such studies are completed, topical metformin should be viewed as an intriguing but unproven idea — a scientific hypothesis, not an established treatment.

References

Bao, Y., Craiglow, B. G., Damsky, W., & Christiano, A. M. (2024). Low-dose metformin improves symptoms and gene expression in central centrifugal cicatricial alopecia. JAMA Dermatology. Retrieved from https://jamanetwork.com/journals/jamadermatology/fullarticle/2822779

Hamada, K., Soga, M., Iwata, C., & Nishimura, E. K. (2021). Metformin promotes the hair-inductive activity of three-dimensional cultured dermal papilla cells. Scientific Reports, 11(1), 23700. Retrieved from https://pubmed.ncbi.nlm.nih.gov/34883492/

Ross, E. V., & St. Surin-Lord, S. (2019). Treatment of central centrifugal cicatricial alopecia with topical metformin: A report of two cases. JAAD Case Reports, 5(12), 1042–1045. Retrieved from https://www.jaadcasereports.org/article/S2352-5126(19)30735-0/fulltext

Williams, J., & Kirby, J. (2024). Adjuvant use of topical metformin with standard therapies in hair loss. JAAD Case Reports, 41, 9–12. Retrieved from https://www.jaadcasereports.org/article/S2352-5126(24)00515-0/fulltext

Zhang, X., Zhao, J., Chen, Z., & Li, H. (2025). Low-dose metformin nanosystem promotes hair growth in mice. Research, 8(1), 780. Retrieved from https://spj.science.org/doi/10.34133/research.0780