Clinical FeaturesWomen’s Health

Contraceptive Choice in Women on Antiepileptic Drugs (AEDs)

Written by Sarah Cullen, (Pharmacy Intern, NMH) & Benedetta Soldati, (Sr. Pharmacist, NMH)


It is crucial to counsel all women of childbearing age about future pregnancies, since half of all pregnancies happen to be unplanned. This recommendation becomes even more important for women with epilepsy, where all pregnancies should be planned and preconception advice should be sought. Considering that 25% of people with epilepsy in Ireland are child-bearing women, this amounts to about 10,000 people who we must consider the use of contraceptives for.

What does contraception involve for a woman with epilepsy?

Contraception can be divided into three main types: natural, barrier and hormonal methods. As natural methods are not appropriate for women of child-bearing age with epilepsy, they will not be discussed further.

Barrier methods include condoms, femidoms, diaphragms and the copper coil. The copper coil is a good alternative for women searching for a long-term contraceptive solution without the hormonal effects. Condoms alone are not strongly recommended because of the risk of failure.

Hormonal methods include the following: combined contraceptive pill (COC), progesterone only pill (mini-pill), contraceptive implant, patch, depot injection, hormonal coil and the vaginal ring. Hormonal contraceptive methods are the most commonly chosen by women, including women with epilepsy.

Enzyme-inducing AEDs and contraception

Enzyme-inducing AEDs can interact with hormonal contraceptives. Interaction types vary: some AEDs may affect the efficacy of contraceptives while some contraceptives affect the efficacy of AEDs (see table below). As a consequence, the rate of oral contraceptive failure is expected to be much higher in women taking enzyme-inducing AEDs compared to the general population. For women on enzyme inducing AEDs, the World Health Organisation (WHO) recommends against the use of the combined hormonal contraception (pill, patch, ring) or progesterone only contraception (implant, mini-pill). The copper IUD, levonorgestrel IUD and the medroxyprogesterone acetatedepot injection (DMPA) are not attenuated by drug interactions, and are therefore the suggested alternative for women on enzymeinducing AEDs.

Emergency contraception choices while taking enzyme-inducing AEDs

Levonorgestrel and ulipristal acetate are the two types of emergency hormonal contraception (EHC). These are both heavily impacted by enzymeinducing medications. The copper coil is a non-hormonal form of emergency contraception (EC) and, as such, it is not affected by enzyme-inducing medications.

As women may present in need of EC, it is strongly recommended that, if EC is necessary, they are referred to their doctor to avail of the copper coil, as this is the safest and most effective form of emergency contraception in those taking enzyme-inducing medications. If it is not possible for a patient to get in touch with their doctor, or if they do not wish to avail of the copper coil, levonorgestrel can be given at double the usual dose (3mg). There is no evidence to recommend the use of ulipristal acetate for patients on enzyme-inducing medications.

Lamotrigine and Sodium Valproate

Lamotrigine levels are decreased by combined hormonal contraception. For women who are taking the COC alongside lamotrigine, this may result in a reduced efficacy of lamotrigine during the pill cycle and an increase in lamotrigine levels during the pill free break. This means women may be more likely to experience loss in seizure control during the pill cycle and experience lamotrigine toxicity on their pill-free interval.

Sodium valproate has caused birth defects in babies whose mothers had taken the drug during pregnancy and, therefore, it is not recommended for the treatment of epilepsy in women of child-bearing age. It is only to be considered if there is no alternative and it must be used in conjunction with the ‘Valproate Pregnancy Prevention Programme’. As a result, it is rarely used in women with childbearing potential. However, it is important to highlight that ethinylestradiol can modestly reduce its levels.


In conclusion, the prevalence of women with epilepsy who are of childbearing age means it is important for healthcare professional to be aware of the considerations of contraception.

Furthermore, women taking AEDs may present looking for preconception advice. Healthcare professionals should advise women who wish to become pregnant while on AEDs to engage with their consultants to optimise their medications and begin a course of folic acid. It is recommended that women on AEDs begin taking 5mg of folic acid at least three months prior to conception and remain on this dose throughout the pregnancy. The HSE National Clinical Programme for epilepsy recommends that women with epilepsy who are considering becoming pregnant engage with preconception planning 12 months before conception.

Though this article focused on women of child-bearing age, it is important to remember that hormonal replacement therapy (HRT) can also interact with AEDs. Common medications used in HRT such as estradiol and dydrogesterone have similar effects to COCs, and while there is no longer a concern of pregnancy, the efficacy of both the HRT and the AED must be considered.

References available on request

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