Study Examines How Epilepsy Drugs May Affect Birth Control

A new study has found that nearly one-third of people with epilepsy prescribed certain hormonal contraceptives were also prescribed antiseizure medications that could reduce their effectiveness, potentially increasing the risk of unintended pregnancy.

Published October 7, 2026, in Neurology, the medical journal of the American Academy of Neurology, the study highlights the importance of understanding potential drug interactions when selecting contraception for people with epilepsy.

Researchers analysed medical records of 21,923 people with epilepsy who were prescribed hormonal contraceptives that can be affected by drug interactions alongside enzyme-inducing antiseizure medications.

The contraceptive methods included combined oral contraceptive pills, progestin-only pills, contraceptive patches, vaginal rings and subdermal implants. The antiseizure medications examined included carbamazepine, oxcarbazepine, phenobarbital, phenytoin and topiramate, among others.

The findings revealed that 7,154 people, representing 32.6% of participants, experienced at least one period of 14 days or longer during which prescriptions for these contraceptives and antiseizure medications overlapped. On average, the overlap lasted approximately seven months.

Certain antiseizure medications can accelerate the breakdown of hormones used in some contraceptive methods, potentially making them less effective.

Researchers highlighted that effective contraception is particularly important for people with epilepsy, as pregnancy may involve increased health risks for both the parent and baby. Some antiseizure medications have also been associated with risks to fetal development. Unplanned pregnancies may limit opportunities to adjust medications and begin folic acid supplementation before conception.

The researchers stressed that not all contraceptive methods are affected by these interactions. Greater awareness and informed contraceptive counselling could help people choose methods suited to their preferences and health needs.

The researchers called for further studies to understand the real-world impact of these overlapping prescriptions.

REFERENCE: Elizabeth Harrison, et al.; Contraceptive and Enzyme-Inducing Antiseizure Medication Coprescription Among US Medicaid Beneficiaries With Epilepsy; Neurology; 2026; https://doi.org/10.1212/WNL.0000000000218679