Neem has been shown to be a powerful, relatively inexpensive birth control agent for both men and women. In the first century B.C., Charaka, the Indian physician, gave a detailed method for using neem for contraception. Cotton soaked in neem oil was kept in the vagina for fifteen minutes before intercourse. This killed the sperm.
In both India and the United States, trials show neem extract reduces fertility in male monkeys without in hiting libido or sperm production. Also, in other Indian studies, neem leaf tablets taken for one month produced reversible male infertility but did not affect sperm production or libido. This shows promise as the first male birth control pill.
In another study, members of the Indian Army were tested with neems birth control effects. Twenty married men took daily oral doses of several drops of neem seed oil in gelatin capsules. To become 100 percent effective, the effect took six weeks, but it remained effective during the entire year of the trial, and was only reversed six weeks after a man no longer took the capsules. The men experienced no adverse side effects and retained their normal capabilities and desires. No women became pregnant during this period. This product is now offered in stores under the name Sensal.
Neems contraceptive uses for women are even more varied. Even the leaves are said to be effective. Many women in Madagascar chew a handful of neem leaves every day, which according to their statements prevents pregnancies. In the case of unwanted pregnancies, neem is said to be capable of inducing a miscarriage.
Neem oil based vaginal creams and suppositories are extremely popular in India. Nonirritating and easy to use, they are almost 100 percent effective. When tested against human sperm, neem extract (sodium nimbidinate) at 1,000mg was able to kill all sperm in five minutes and required only 30 minutes at a lower, 250 mg level. It is suggested that these creams and suppositories also prevent vaginal and sexually transmitted diseases.
Oddly, neem oil has also been taken internally by ascetics who wish to diminish their sexual desire.