OCPs are widely available and advocated for use in the adolescent population. They work via several mechanisms of action, but the most important for providing contraception is estrogen-induced inhibition of the midcycle surge of gonadotropin secretion so that ovulation does not occur. Combination OCPs are potent in this regard, but progestin-only pills are not. Although, OCPs are widely available and used, they do carry some inherent risks. Contraindications include previous thromboembolic event, history of an estrogen-dependent tumor, liver disease, pregnancy, undiagnosed abnormal uterine bleeding, cerebral vascular or coronary artery disease, women older than 35 years who smoke heavily (>15 cigarettes/day).

It is imperative that one does not prescribe OCPs to females with undiagnosed vaginal bleeding. The patient may be pregnant in which case the hormonal therapy may induce bleeding or result in birth anomalies. Also, breakthrough bleeding is one of the best known side effects of OCPs. This occurs because the endometrial lining thins, becomes less stable on hormonal therapy (particularly combination estrogen-progesterone therapy), and becomes more prone to breakdown, with resultant bleeding. A systematic workup for abnormal uterine bleeding should be initiated on presentation. The first two steps of this include a pregnancy test and determining through history whether the bleeding is ovulatory or anovulatory in nature. Follicle-stimulating hormone and leuteinizing hormone levels may assist with this determination.