On the Contraceptive Effect of Castor Beans

Castor beans (Ricinus communis L., Euphorbiaceae) have been used traditionally by women in many countries for birth control. In order to verify the contraceptive effect of castor beans, adult female rabbits were treated orally with chunks of castor beans at the level of 7.5 mg/kg body weight daily for at least ten consecutive days. Mating with proven male rabbits was allowed after the last treatment. Treated and untreated (control) female rabbits were inspected for pregnancy, body weight, and any apparent side effects. The treatment resulted in a 4.3 fold decrease in pregnancy of treated female rabbits compared to the untreated control group. All treated female rabbits experienced transient mild diarrhea and loss of body weight. The inhibitory effect of castor beans on pregnancy was reversible. This observation was detected by remating four females who were treated with castor beans previously. Three of these rabbits became pregnant and delivered at term (after 32 days), whereas the fourth rabbit experienced midgestation abortion (day 16 of pregnancy). These results suggest a reversible contraceptive effect of castor bean in female rabbits.