It has been suggested that rosemary oil increases hair growth by improving blood circulation in the scalp. One study tested the application of rosemary oil against 2% Minoxidil solution and after 6 months both groups in the test showed significant improvement in hair growth and similar levels.
A clinical trial was conducted by Hay et al (1998) to investigate if pharmacologically active stimulants for hair growth are present in rosemary and whether they have a therapeutic effect. In this study, 86 patients diagnosed with alopecia areata (a hair loss condition) were divided into 2 groups – control group and essential oils group.
The essential oils group rubbed rosemary, cedarwood, thyme and lavender mixed in jojoba oil and grapeseed oil daily while the control group used just jojoba oil and grapeseed oil. At the end of the trial period (7 months), 44% of patients in the essential oils group showed improvements in hair regrowth whereas in the control group, only 15% had improvement. The success of treatment in this study compares well with that of standard treatment practices used conventionally (Bedi, 2002).
Figure 1: A patient showing an excellent response to essential oil therapy (Hay et al, 1998)
Kazunya et al (2013) conducted a study on mice to verify if rosemary leaf extract promotes hair growth. They topically applied the leaf extract on mice whose hair growth had been interrupted intentionally and observed an improvement in hair regrowth. In the same study, improved hair regrowth was also noted in mice whose dorsal areas had been shaved. They concluded that rosemary leaf extract was a crude drug of interest for hair growth.
In addition to the positive results in the above studies, Begum et al (2013), Al-Sereiti et al (1999) and Edwards et al (2015) all cite rosemary oil as a hair growth promoter. However, trials to investigate uses of rosemary on specific conditions are very few (Fugh-Berman, 2003). Consequently, the promotion of hair growth by rosemary oil alone in humans is still not fully substantiated scientifically. Hence, despite it being known traditionally as a hair growth promoter, it does not appear on the FDA list of approved medications for hair loss. The list is only limited to two, Rogaine® and Propecia® (Rogers, 2013).