Histopathological studies on rats' vagina, cervix, and uterus showed no ill effects of neem oil in these tissues. In contrast, nonyl-phenoxy polyethoxy ethanol, a popular vaginal contraceptive cream, showed signs of severe irritant reaction in these tissues. Radioisotope studies indicated that neem oil was not absorbed from the vagina; it thus ruled out its possible systemic effects.
Results of the present study indicate than neem oil is an "ideal" female contraceptive, being easily available, cheap, and nontoxic. Therefore, its mass acceptance is anticipated.
N.L. Sadre, Vibhavari Y. Deshpande, K.N. Mendulkar, and D.H. Nandal. 1983. Male antifertility activity of Azadirachta indica in different species. Pages 473-482 in H. Schmutterer and K.R.S. Ascher, eds. 1984. Natural Pesticides from the Neem Tree (Azadirachta indica A. Juss.) and other tropical plants. Deutsche Gesellschaft für Technische Zusammenarbeit (GTZ), Eschborn, Germany.
Male antifertility activity of neem (Azadirachta indica A. Juss) was studied in mice, rats, rabbits, and guinea pigs by daily oral feeding of a cold-water extract of fresh green neem leaves. The infertility effect was seen in treated male rats, as there was a 66.7 percent reduction in fertility after 6 weeks, 80 percent after 9 weeks, and 100 percent after 11 weeks. There was no inhibition of spermatogenesis. During this period there was no decrease in body weight and no other manifestation of toxicity were observed. There was a marked decrease in the motility of spermatozoa. The infertility in rats was not associated with loss of libido or with impotence and the animals maintained normal mating behavior. The male antifertility activity was reversible in 4 to 6 weeks and the active principle from the extract was observed to be thermostable. Neem extract also shows reversible male antifertility activity in mice without inhibition of spermatogenesis. In guinea pigs and rabbits, however, it exhibited toxicity, as demonstrated by 66.6 percent and 74.9 percent mortality in guinea pigs and 80 percent and 90 percent mortality in rabbits at the end of 4 and 6 weeks, respectively.