Overview of choice of combined oral contraceptive

Formulations of combined oral contraceptives (COCs) available in Australia are listed in Formulations of combined hormonal contraception available in Australia. COCs are primarily differentiated by estrogen dose and whether the dose changes throughout the cycle (monophasic, triphasic or quadriphasic). Formulations also vary in the type of estrogen and progestogen contained, and the number of inactive pills per cycle. See Dose and type of estrogen and type of progestogen for implications for choice of formulation.

There are few head-to-head trials to guide the choice of COC formulation. Some COC formulations have specific indications in addition to contraception (eg acne); however, this does not indicate superiority to other formulations (in which trials to examine effect on acne have not been undertaken).

Triphasic COCs contain pills with varying doses of hormones (within the standard range for estrogen). They were developed in the 1980s to try to minimise adverse effects seen with monophasic COCs. They are no longer commonly used because there is no evidence that varying the dose of hormones is beneficial, and they are generally not used for extended or continuous use because there is a chance of breakthrough bleeding when switching doses.

A quadriphasic pill containing estradiol valerate and dienogest in an estrogen step-down and progestogen step-up sequence (Qlaira) aims to reduce blood loss; it is indicated for heavy menstrual bleeding as well as contraception. It is not available on the PBS and has complex instructions for managing a missed pill.