Print Print
CKS is no longer commissioned by the National Institute for Health and Clinical Excellence (NICE). NICE remains committed to providing a replacement service for CKS and is currently reviewing its options. In the meantime, although CKS content is now not being maintained, it still remains relevant and will continue to be made available. CKS content was generated under a programme of topic creation and update. To check if the topic you are viewing is current or out of date, please refer to the topic publication details by clicking on the 'How up-to-date is this topic?' link in the left hand menu on individual topic pages.

Contraception - Management
Drug interactions: what should be done?

  • The efficacy of the ring may be reduced by liver enzyme-inducing drugs, and non-liver enzyme-inducing antibiotics (excluding amoxicillin and doxycycline which do not appear to be affected).
    • If a woman is taking a liver enzyme-inducing drug, advise her to use additional barrier contraception for the duration of treatment and for 28 days after its discontinuation, or choose another method of contraception. If the drug treatment runs beyond the 3 weeks of her cycle, advise her to insert the next ring immediately without a ring-free week.
    • If a woman is taking non-liver enzyme-inducing antibiotics (excluding amoxicillin and doxycycline), advise her to use additional barrier contraception for the duration of treatment and for 7 days after their discontinuation. If the drug treatment runs beyond the 3 weeks of her cycle, advise her to insert the next ring immediately without a ring-free week.
  • Specifically relating to the vaginal ring:
    • Vaginally administered spermicide has no effect on the efficacy or safety of the ring.
    • Antifungal drugs do not appear to affect the efficacy of the ring, but miconazole may cause increased release of ethinylestradiol and etonogestrel from the ring, resulting in higher serum levels of these hormones.
    • Antifungal ovules may increase the risk of ring breakage.
  • For more information on potential drug interactions, see:
Basis for recommendation
  • These recommendations are based on the Summary of Product Characteristics (SPC) for NuvaRing® combined vaginal ring, and a Faculty of Sexual and Reproductive Healthcare review [ABPI Medicines Compendium, 2009b; FSRH, 2009a; FSRH, 2010a].
    • Ethinylestradiol and etonogestrel are metabolized in the liver, so drugs that induce liver enzymes may reduce the contraceptive efficacy of the ring.
    • In clinical trials, use of the ring with amoxicillin and doxycycline did not significantly affect the pharmacokinetics of ethinylestradiol and etonogestrel. Evidence is lacking for other antibiotics, therefore the SPC recommends the use of additional barrier contraception when using non-liver enzyme-inducing antibiotics (except amoxicillin and doxycycline) and for 7 days after their discontinuation.

© NHS Institute for Innovation and Improvement