Femilon is a low-dose combined oral contraceptive pill containing desogestrel (0.02mg) and ethinyl estradiol (0.02mg) that prevents pregnancy by stopping ovulation, thickening cervical mucus, and thinning the uterine lining. As one of the lowest-dose birth control pills available, it's often recommended for women who experience side effects with higher-dose pills, and it may also help regulate periods, reduce menstrual cramps, and improve acne.