Effectiveness of Minoxidil: Evidence and Explanation

Effectiveness of Minoxidil: Evidence and Explanation

Minoxidil is a vasodilator that is used as a medicine to treat hypertension and even hair loss. Its use in the specific realm of hair care has become popular among men and women suffering from specific types of hair loss such as androgenetic alopecia.

Nevertheless, for treating hair loss and promoting hair growth on the scalp or hair in other parts of the body such as the beard, minoxidil can be purchased as a topical over-the-counter product without a prescription or as an oral medication with a prescription.

Understanding Why Minoxidil is Effective: Evidence and Explanation from Science

Evidence According to Studies

Topical minoxidil is effective for treating hair loss due to androgenetic alopecia regardless of sex. This means that it can help men suffering from male-pattern hair loss and women with female-pattern hair loss.

It is also prescribed in people with other non-scarring causes of hair loss such as due to chronic stress. An oral formulation of this medication is sometimes prescribed to individuals who are not responding to topical products.

There is a wealth of documented evidence attesting to the effectiveness of minoxidil. The following are some notable studies and conclusions demonstrating the evidence of the effectiveness of minoxidil in treating hair loss:

• Researchers A. K. Gupta and A. Charrette did a systematic review and meta-analysis of previous studies involving men with androgenic alopecia or male pattern hair loss. Their findings showed that topical minoxidil is more effective than a placebo in promoting total and nonvellus or thicker and coarser hair.

• Findings from another study by Anne W. Luck et al. revealed that topical minoxidil was effective for women with androgenetic alopecia of female pattern hair loss. Participants who used a 5 percent solution demonstrated positive change in nonvellus hair count, overall hair growth, and scalp coverage after 48 weeks.

• Several studies, including an expansive literature review from P. Suchonwanit, S. Thammarucha, and K. Leerunyakul, showed that a topical solution of 5 percent was more effective in treating men and women with androgenetic alopecia than a solution containing 2 percent minoxidil and placebo treatment.

• Another research by A. K. Gupta concluded that a 5-milligram dose of oral minoxidil was significantly more efficacious than 5 percent and 2 percent solutions of topical minoxidil and other oral dihydrotestosterone or DHT reductase inhibitors or DHT blockers such as a 1-milligram dose of finasteride at 24 weeks.

Possible Scientific Explanations

Remember that minoxidil is a vasodilator. A vasodilator is a drug that promotes vasodilation or the widening of blood vessels due to the relaxation of smooth muscles within the vessel walls.

Most experts believe that the aforementioned vasodilating effect is the reason why minoxidil is effective against hair loss or for promoting hair growth.

However, the full and exact mechanism behind its hair-growing effect remains not understood. The following are the possible scientific explanations:

• One of the possible explanations behind the effectiveness of minoxidil in treating hair loss and promoting hair growth is that it is a potassium channel opener because it is sensitive to adenosine triphosphate. This theoretically allows the hyperpolarization of cell membranes and stimulates or supports hair growth by allowing more blood, oxygen, and nutrients to the hair follicles.

• The medication also contains a nitric oxide moiety and may act as a nitric oxide agonist. This theoretically causes the hair follicles in the dormant or telogen phase to shed and then enter a new growth or anagen phase which results in denser hair growth. Hair strands that shed are replaced by thicker hair strands.

• Several in vitro effects of minoxidil has been observed and described in monocultures of different skin and hair follicle cell types. These include the stimulation of cell proliferation, inhibition of collagen synthesis, and stimulation of vascular endothelial growth factor, prostaglandin synthesis, and leukotriene B4 expression

• Minoxidil also activates uncoupled sulfonylurea receptor on the plasma membrane of dermal papilla cells and upregulates the expression of genes responsible for growth factors such as VEGF, HGF, and IGF-1 while also enhancing the actions of these cell growth factors. The medication can stimulate the growth of hair follicle cells and this results in hair growth and an improvement in the overall health of the hair.

The aforementioned possible explanations describe three possible mechanisms behind the effectiveness of minoxidil. These include working as a vasodilator that widens the blood vessels and improves blood flow to the hair follicles, inducing and prolonging the anagen phase of the hair growth cycle, and stimulating the growth of healthier hair follicle cells.

Notable Limitations of Minoxidil: Instances and Specific Cases of Ineffectiveness

However, despite the aforementioned evidence from studies and explanations about the effectiveness of minoxidil, it is important to highlight the fact that this medication does not address all types and causes of hair loss. The following are its limitations:

• Some people have a negative reaction characterized by localized irritation to a typical water-based minoxidil solution containing ethanol and propylene glycol. These two ingredients enhance solubility and drug delivery into the hair follicles. An irritated scalp or skin can inflame and damage the hair follicles and result in hair loss.

• A foam-based formulation that does not contain ethanol and propylene glycol was developed to address the problems with a water-based solution. It is also important to underscore the fact that studies showed that the foam-based variant of topical minoxidil improves targeted drug delivery and its easier penetration with less irritation.

• Researchers D. T. Scow, R. S. Nolte, and A. F. Shaughnessy noted that is less effective when the area of hair loss is large. It also seems to be more effective among younger individuals who have experienced hair loss for less than 5 years and those individuals who are losing hair on top of their scalp.

• It is also important to highlight the fact that minoxidil is effective in individuals suffering from androgenetic alopecia. There are other causes and types of hair loss. This medication is not effective against alopecia areata, which is an autoimmune disorder, and telogen effluvium, which is a multifactorial type of hair loss.


  • Gupta, A. K. and Charrette, A. 2015. “Topical Minoxidil: Systematic Review and Meta-Analysis of its Efficacy in Androgenetic Alopecia.” Skinmed. 13(3): 185-189. PMID: 26380504
  • Lucky, A. W., Piacquadio, D. J., Ditre, C. M., Dunlap, F., Kantor, I., Pandya, A. G., Savin, R. C., and Tharp, M. D. (2004). “A Randomized, Placebo-Controlled Trial of 5% and 2% Topical Minoxidil Solutions in the Treatment of Female Pattern Hair Loss. Journal of the American Academy of Dermatology. 30(4): 541-533. DOI: 1016/j.jaad.2003.06.014
  • Scow, D. T., Nolte, R. S., and Shaughnessy, A. F. 1999. “Medical Treatments for Balding Men.” American Family Physician. 59(8): 2189-2194. PMID: 10221304
  • Suchonwanit, P., Thammarucha, S., and Leerunyakul, K. 2019. “Minoxidil and Its Use in Hair Disorders: A Review.” Drug Design, Development, and Therapy. 13: 2777-2786. DOI: 2147/dddt.s214907
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