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Contraception - Management
What advice should I give regarding potential drug interactions with the progestogen-only pill (POP)?

  • Interactions:
    • Liver enzyme–inducing drugs can affect the efficacy of the progestogen-only pill (POP). Commonly encountered liver enzyme–inducing drugs are:
      • Antibiotics: rifampicin and rifabutin.
      • Anticonvulsants: carbamazepine, oxcarbazepine, phenytoin, phenobarbital, primidone, topiramate.
      • Herbal remedies: St John's wort.
      • Antiretrovirals: drug interactions between certain antiretroviral agents and hormonal contraceptives could alter the safety and effectiveness of both the hormonal contraceptives and the antiretroviral agents. See antiretrovirals.
    • Antibiotics that do not induce liver enzymes (i.e. all antibiotics except rifampicin and rifamycin) do not reduce the effectiveness of POPs.
  • Precautions:
    • The woman should check with a healthcare professional whether a drug interaction could be problematic before she starts using any drug or herbal remedy.
    • The woman may choose to continue with the POP if she is receiving a short course of an interacting drug, but she should use additional contraception (e.g. condoms) whilst taking the drug and for 4 weeks after finishing the course.
    • Women receiving long-term courses of drugs that continue to interact with hormonal contraception should consider an alternative contraceptive method for which interaction is not a problem:
    • Emergency contraception should be considered if sexual intercourse has taken place in the past 5 days and the efficacy of the POP is doubtful. See the CKS topic on Contraception - emergency.
Clarification / Additional information
Basis for recommendation
  • This advice is based on guidelines from the Faculty of Sexual and Reproductive Healthcare (FSRH), formerly the Faculty of Family Planning and Reproductive Healthcare (FFPRHC) [FFPRHC, 2005d; FFPRHC, 2006a; FSRH, 2010a].
    • Although the interaction of rifampicin or certain anticonvulsants with progestogen-only pills (POPs) is not harmful to women, it is likely to reduce the effectiveness of POPs.
    • Evidence is insufficient to be certain that increasing the hormone dose of POPs will ensure effective contraception with long-term use of liver enzyme–inducing drugs.
    • Limited data suggest that potential drug interactions between many antiretroviral agents and hormonal contraceptives may alter the safety and effectiveness of both the hormonal contraceptives and the antiretroviral agents.
    • There is evidence that progestogen-only methods are not affected by lamotrigine.

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