At this time 3 triphasics are widely used in the US: Ortho-Novum 7/7/7, Tri-Norinyl, and Triphasil. Ethinyl estradiol is the preferred estrogenic agent for the triphasic products. Torethindrone and levonorgestrel were chosen as the progestins for the triphasic products. It is the combined effects of estrogen and progestin in the triphasics that provide their contraceptive action. Triphasil increases both the estrogen and the progestin at midcycle; Tri-Norinyl and Ortho-Novum 7/7/7 elevate the progestin only. The midcycle surges of estrogen and luteinizing hormone are dampened, and ovulation is inhibited. The triphasics represent a 98.7% reduction in total steroid content since oral contraceptives (OCs) were introduced. An estrogen dose of 30-50 mcg will inhibit ovulation, and side effects with such a dose are considered tolerable. The triphasic OCs are in this range. An estrogen dose of 20 mcg has been tested but is slightly less effective and is not recommended. Contraceptive failures have occurred with the triphasic products. In 1486 women studied, 6 pregnancies have occurred. Of these failures, one may have been because of a drug interaction with a barbituate. 1 pregnancy was due to patient failure; 3 consecutive pills were missed. Only 2 pregnancies were certain drug failures. Because of the gentle suppression of ovarian function, it has been observed that the menstrual flow is less affected than by standard OCs. Due to the fact that less total steroid is delivered and more endometrial shedding occurs, it is hoped that the triphasic preparations will have less of a "lingering" effect on the return to functional fertility. Most of the published data on side effects is available from the UK, North America, and Europe on the formulation known in the US as Triphasil. Nausea, vomiting, breakthrough bleeding, weight gain, and breast tenderness appear to be the most common side effects. The major medical reasons for triphasic discontinuation include breast tenderness, weight gain, breakthrough bleeding, nausea and vomiting, headache, and increased bleeding during the 1 week of withdrawal. Rifampin and phenobarbital are examples of drugs found to decrease pill efficiency, including triphasics. Also, a triphasic may interfere with the action of another drug. The new triphasics are appropriate when starting new patients on OCs. Patient counseling is essential. Due to the low margin of error as a consequence of lesser suppression of ovarian function, the patient needs to be well instructed in how to take the pill and advised of the consequences of missed tables.