Nevirapine modestly reduces the
plasma concentrations of ethinylestradiol and norethisterone, which could reduce the
efficacy of contraception. The
efficacy of emergency hormonal
contraceptives and progestogen-only implants or injections may also be reduced by
nevirapine.
For general advice on the use of
enzyme inducers, such as
nevirapine, and
contraceptives, see
contraceptives. However, note that the manufactur- ers of
nevirapine recommend that combined hormonal
contraceptives should not be used as the sole method of contraception in women taking
nevirapine. They suggest that a barrier method (e.g. condoms) should also be used, and note that this is also advisable to reduce the risk of HIV
transmission. They also suggest that if combined hormonal
contraceptives are used for reasons other than contracep- tion (e.g. endometriosis), that the therapeutic effect should be monitored and the dose increased if necessary.