Clarification: Although the interaction of rifampicin or rifabutin therapy with COCs, P, CVR or CICs is not harmful to women, it is likely to reduce the effectiveness of COCs, P, CVR or CICs. Use of other contraceptives should be encouraged for women who are long-term users of either of these drugs. When a COC is chosen, a preparation containing a minimum of 30 µg EE should be used.