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Contraception - Management
What should I advise a woman regarding potential drug interactions with combined oral contraceptives (COCs)?

  • For a woman who is planning to use a combined oral contraceptive (COC):
    • Inform her that some drugs (including antibiotics) can reduce the efficacy of the COC, and vice versa:
      • These can be prescription drugs or those bought over the counter, as well as natural or herbal remedies that are widely available without restriction.
    • Advise the woman to check with a healthcare professional the possibility of drug interaction before starting any drug therapy (including herbal remedies).
    • Provide her with verbal and written instruction on additional contraceptive measures to use (e.g. condoms) if the contraceptive effect of COC could be compromised.
Clarification / Additional information
  • Drugs that may impair the efficacy of the combined oral contraceptive (COC) include:
  • Other significant drug interactions include:
    • Lamotrigine — see Lamotrigine.
    • Orlistat:
      • Although no interactions between COCs and orlistat have been demonstrated in specific studies, orlistat may indirectly reduce the availability of COCs and lead to unexpected pregnancies in some cases [ABPI Medicines Compendium, 2005].
      • An additional contraceptive method is recommended if the woman has severe diarrhoea whilst taking orlistat.
  • COCs can alter (increase or decrease) serum concentrations of other drugs, such as theophylline and ciclosporin.
  • For more information on drug interactions with COCs, see the British National Formulary [BNF 53, 2007].
Basis for recommendation
  • These recommendations are based on guidelines published by the Faculty of Sexual and Reproductive Healthcare (FSRH), formerly the Faculty of Family Planning and Reproductive Healthcare (FFPRHC) [FFPRHC, 2005d; FFPRHC, 2007b; FSRH, 2009b].

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