Abstract
<jats:title>Abstract</jats:title> <jats:p>COCs prevent ovulation and also reduce sperm penetrability of cervical mucus. Highly effective in consistent users, they remove the normal menstrual cycle and replace with a cycle which is user-produced, so the withdrawal bleeding has minimal medical significance, can be deliberately made infrequent, and, if it fails to occur, once pregnancy is excluded, poses no problem. The pill-free interval is the contraception-deficient time, which has great relevance to the advice if tablets are missed. The numerous non-contraceptive benefits of COCs are often overlooked, yet may sometimes provide the principal indication for COC-use. They include protection against cancer of the ovary, endometrium, colon, and rectum, hence balancing the possible promotion of other cancers—in some circumstances only and reassuringly with no sustained effect in ex-users. Venous thromboembolism and arterial disease risks can be minimized by careful selection of users, taking account of WHO eligibility criteria, interacting diseases and known risk factors such as obesity and migraine with aura. Interacting drugs can affect efficacy or be themselves affected. There should be forewarning about recognized side effects, whether hormonal or ‘breakthrough’ bleeding, and after checking against the ‘D-Checklist’ for the latter, appropriate management during follow-up: usually by substituting a different formulation or a different contraceptive. Once stabilized, COC-takers need an annual review of blood pressure, headache history, and any new risks or side effects, though they should know they can return any time for advice. Some women prefer transdermal and transvaginal combined hormonal methods (EvraR, NuvaRingR) which are very similar but avoid taking daily tablets.</jats:p>