High doses of estrogens, with or without a progestin, have been used for many years to prevent pregnancy after unprotected coitus (Medical Letter, 31:93, 1989). Now the FDA has approved marketing of the Preven Emergency Contraceptive Kit (Gynetics, Inc.) for this indication. The kit, which will require a prescription, includes four tablets, each containing 50 g of ethinyl estradiol and 0.25 mg of levonorgestrel, and a pregnancy test to rule out a pre-existing pregnancy, which would be a contraindication to taking the hormones.

Two types of oral contraceptives are available in the USA: combination oral contraceptives that contain both an estrogen and a progestin, and progestin-only contraceptives, or "mini-pills."Used as directed, all oral contraceptives marketed in the USA are similarly effective in preventing pregnancy.