Androgenetic alopecia (AGA), also known as congenital hair loss, is characterized by the progressive thinning and subsequent loss of hair on the head. AGA usually occurs around the age of 20; by the age of 50, almost 50% of all men are affected. This widespread dermatological phenomenon affects both men and women and usually has a negative impact on the quality of life of those affected.

Currently available active ingredients against congenital hair loss are mainly oral finasteride (butyl-3-oxo-4-aza-5α-androst-1-en-17β-carbamide) and locally applied minoxidil (6-piperidin-1-ylpyrimidine-2,4-diamine 3-oxide). The pyrimidine derivative minoxidil is also used to treat high blood pressure, although its exact mechanism of action on hair growth is still unclear. Finasteride is also used against benign hyperplasia of the prostate and is a synthetic 5-alpha-reductase inhibitor. However, use against hair loss is often accompanied by various side effects, such as itching due to eczema formation, increased heart rate, breathing difficulties, sudden weight gain, edema formation and skin inflammation or, in the case of finasteride, reduced libido, impotence and reduced ejaculate volume.

In the underlying study, the hair growth-promoting effects of a 3% minoxidil solution were compared with those of peppermint oil.

Over a period of four weeks, C57BL/6 mice were divided into four groups; each group contained either a saline solution, jojoba oil, a 3% minoxidil solution or peppermint oil. In each group, the assigned substance was applied topically over a period of four weeks.

The hair growth-promoting effect was evaluated in the course of the study. In addition to determining the hair growth rate and histological examinations, this also included the evaluation of various known biomarkers for increased hair growth, such as the enzymatic activity of alkaline phosphatase (ALP) and the expression of the growth factor IGF-1. In addition, the data obtained was statistically analyzed.

Of the four experimental groups, the peppermint oil group showed the most outstanding hair growth effects, namely a significant increase in dermal thickness, follicle number and follicle depth.

In the third week of the study, peppermint oil showed remarkable results and was the active ingredient that caused the most hair regrowth. In the fourth week, peppermint oil showed a hair regrowth score of about 92%, whereas the 3% minoxidil solution was only about 55%.

The histological analysis showed that a four-week topical application of peppermint oil caused very thick and long hair growth and promoted the elongation of the hair follicles from the dermis to the subcutis. These results show that the hair follicles in the peppermint oil group of the study were in the anagen phase in the fourth week of the study. In addition, an increase in epidermal thickness was noted in the peppermint oil group.

Conclusion

The study proved that peppermint oil increases hair growth remarkably strongly and even faster than a 3% minoxidil solution.

Underlying study:

Oh, J. et al: Peppermint Oil Promotes Hair Growth without Toxic Signs; in: Toxicological Research 2014 Dec; 30(4): 297-304.