New contraceptive interaction advice

The Faculty of Sexual and Reproductive Healthcare (FSRH) Clinical Effectiveness Unit has reviewed its guidance on drug interactions with hormonal contraception. The updated guidance includes new advice on the interaction between antibiotics and enzyme-inducing agents.

For many drugs there is a paucity of good quality, robust evidence on their interaction with hormonal contraception | SCIENCE PHOTO LIBRARY
For many drugs there is a paucity of good quality, robust evidence on their interaction with hormonal contraception | SCIENCE PHOTO LIBRARY

The guidance now states that patients treated with non-enzyme inducing antibiotics are not required to take additional contraceptive precautions during or after the course of antibiotic treatment unless vomiting or diarrhoea occurs (as a result of the treatment or infection). Women should be reminded about the importance of managing their contraception during periods of illness.

For women starting enzyme-inducing agents, a contraceptive method unaffected by these drugs should be chosen (eg, progestogen-only injections, copper IUDs or the levonorgestrel-releasing IUS). Alternatively, if an enzyme inducer is being used only short-term, women may opt to continue with a combined oral contraceptive (COC) containing at least 30 microgram ethinylestradiol (EE), the patch or ring, with the use of additional contraception (eg condoms) during and for 28 days after stopping treatment. An extended or tricycling regimen should be used with a hormone-free interval of 4 days.

For women who are on long-term treatment with an enzyme-inducing drug (except the very potent inducers rifampicin and rifabutin) or who do not wish to use additional contraception, the dose of COC may be increased to at least 50 microgram EE (maximum 70 microgram) during and for 28 days after treatment. Use of an extended or tricycling regimen, with a pill-free interval of 4 days, is recommended.

Women using the progestogen-only pill (POP) or implant while on short-term treatment with an enzyme inducer may opt to continue the method, with the use of additional contraceptive precautions during and for 28 days after stopping the drug.

Women requiring emergency contraception should be advised that additional precautions are required for 14 days after taking ulipristal acetate (9 days for the POP, 16 days for estradiol valerate + dienogest). This recommendation is outside the product licence.

Women requiring contraception should always be asked about their current and previous medication use including prescription, OTC, herbal and recreational drugs and dietary supplements, and informed that they should consult a healthcare professional before starting any new medication.

FSRH guidance on drug interactions with hormonal contraception

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