This study has a very small sample size, and it appearaed in an herbalist journal. I don't believe it is conclusive.
Antihirsutism activity of Fennel (fruits of Foeniculum vulgare) extract. A double-blind placebo controlled study.
Phytomedicine 2003;10(6-7):455-8 (ISSN: 0944-7113)
Javidnia K; Dastgheib L; Mohammadi Samani S; Nasiri A
Faculty of Pharmacy, Shiraz University of Medical Sciences, Shiraz, Iran. firstname.lastname@example.org.
Idiopathic hirsutism is defined as the occurrence of excessive male pattern hair growth in women who have a normal ovulatory menstrual cycle and normal levels of serum androgens. It may be a disorder of peripheral androgen
In this study we evaluated the clinical response of idiopathic hirsutism to topical Fennel extract. Fennel, Foeniculum vulgare, is a plant, which has been used as an estrogenic agent. The ethanolic extract of Fennel was obtained by using a soxhlete apparatus.
In a double blind study, 38 patients were treated with creams containing 1%, 2% of Fennel extract and placebo. Hair diameter was measured and rate of growth was considered. The efficacy of treatment with the cream containing 2% Fennel is better than the cream containing 1% Fennel and these two were more potent than placebo. The mean values of hair diameter reduction was 7.8%, 18.3% and -0.5% for patients receiving the creams containing 1%, 2% and 0% (placebo) respectively.