Hair loss is a distressing condition that is associated with a multitude of natural, medical, or nutritional conditions. For example, androgenetic alopecia in men, or male pattern baldness, is increasingly recognized as a physically and psychologically serious medical condition that often requires a professional care by generalist clinicians.

The only products sanctioned by the US FDA for hair loss treatment are oral finasteride (Proscar®) and topical minoxidil (Rogaine®). Minoxidil was originally created as a hypertension medication by Upjohn Pharmaceuticals . Upjohn itself has warned of possible negative side effects from the medication including increased heart rate, difficulty breathing, rapid weight gain, edema, seborrheic dermatitis, scalp itching, and scaling .

Traditional plant remedies have been used for centuries in the treatment for hair loss, but only a few have been scientifically evaluated.Peppermint (Mentha piperita) extracted from peppermint leaves is generally regarded as an excellent carminative and gastric stimulant, and also has been used in cosmetic formulations as a fragrance component and a general skin conditioning agent. The principal ingredient of peppermint oil, menthol, is primarily responsible for its beneficial effects .In vitro, peppermint has been reported to show anti-inflammatory, antimicrobial, and antifungal activities as well as strong antioxidant activity, and antiallergenic and antitumor actions . Several clinical trials examining the effects of peppermint oil (PEO) on irritable bowel syndrome have been reported . However, experimental trial of PEO in its hair growth activity has not been fully reported. The aim of this study was to address the therapeutic potential of PEO for hair loss via the comparative analysis between PEO and minoxidil.

The drugs for alopecia treatment have been developed to maintain or induce the anagen stage of hair cycle. ALP activity was particularly detected in the dermal papilla. ALP activity in the dermal papilla was moderate in very early anagen, reached a maximal level in early anagen, and was kept at a low level during .The bulbar dermal sheath showed intense ALP activity only in early anagen .Although results from clinical trials vary, the majority of the evidence indicates that there is a direct correlation between the hair follicle depth and the level of ALP activity. In this NIH study,  study, PEO induced significantly high ALP activity at week 2, even greater than MXD. This study demonstrates that PEO stimulates both dermal papilla and ALP activity, which promotes blood circulation by relaxing vascular smooth muscle .

To better understand the influence of the endocrine system in hair growth, researchers analyzed the mRNA expression of IGF-1 gene. It is a potent mitogen supporting cell growth and survival  and also plays a role to increase hair thickness .In this study, PEO showed remarkably increased IGF-1 mRNA expression at week 2, whereas MXD at week 4.

In conclusion, the researchers experimental data suggested that a 3% PEO  facilitates hair growth by promoting the conservation of vascularization of hair dermal papilla, which may contribute to the induction of early anagen stage. In addition, PEO effectively stimulated hair growth in an animal model via several mechanisms and thus could be used as a therapeutic or preventive alternative medicine for hair loss in humans.