Nearly one-third of people with epilepsy who were prescribed certain hormonal contraceptives also received antiseizure medications that may make those contraceptives less effective, according to a University of Pittsburgh-led study published today in Neurology , the medical journal of the American Academy of Neurology .
Some epilepsy medications may harm a developing fetus, so the findings point to a need for greater awareness of interactions between enzyme-inducing antiseizure medications and some hormonal contraceptives. These medications can accelerate the breakdown of contraceptive hormones in the body, potentially reducing protection against an unplanned pregnancy. The researchers emphasize the importance of informed counseling and shared decision-making so that people with epilepsy can choose medication and contraceptive options that reflect their health needs and preferences.
“Pregnancy planning is especially important for people with epilepsy, but patients may not realize that some antiseizure medications can interact with some forms of hormonal contraception,” said senior author Page B. Pennell, M.D., chair of the Department of Neurology at Pitt’s School of Medicine. “This study highlights an opportunity for neurologists, reproductive health clinicians, pharmacists and patients to have more coordinated conversations about medications, contraception and reproductive goals.”
Using U.S. Medicaid claims data, the researchers identified 110,976 people with epilepsy of childbearing potential who were receiving antiseizure medications. Nearly 1 in 5 had received a hormonal contraceptive that could be affected by enzyme-inducing antiseizure medications between 2018 and 2021. The contraceptive methods included combined and progestin-only pills, contraceptive patches, vaginal rings and subdermal implants.
Among those individuals, nearly one-third experienced at least one period of 14 days or longer when prescriptions for a susceptible contraceptive and an enzyme-inducing antiseizure medication overlapped. Among people with an overlap, the median duration was 218 days, or just over seven months.
“These were not simply brief or isolated prescription overlaps,” said corresponding author Laura Kirkpatrick, M.D., M.S., assistant professor of pediatrics and neurology at the University of Pittsburgh School of Medicine. “For many people, the overlap continued for months. Clinicians should routinely consider potential drug interactions and make sure patients understand their options, including contraceptive methods that are not affected by enzyme-inducing antiseizure medications.”
Certain groups were more likely to experience potentially reduced contraceptive effectiveness. People with intellectual disability had more than twice the odds of experiencing an overlap compared with people without intellectual disability. Those with drug-resistant epilepsy and those age 35 or older also had higher odds of overlap and longer periods of concurrent prescriptions.
Effective contraception can be particularly important for people with epilepsy because pregnancy can bring additional health considerations. Some antiseizure medications have been associated with risks to a developing fetus, as have uncontrolled seizures. An unplanned pregnancy may provide less opportunity to adjust medications to ones that are proven to be safe for both the mother and developing child.
The researchers noted that not all contraceptive methods are affected by these interactions. Intrauterine devices, including hormonal and copper devices, are not affected by enzyme-inducing antiseizure medications and may be discussed as an option when consistent with a patient’s preferences. Co-use of an interacting medication combination may also be appropriate in some circumstances when a patient understands the potential risks and benefits.
Future research will examine pregnancy rates among people who received overlapping prescriptions and explore why these medication combinations are prescribed. The authors also call for research into interventions such as electronic health record alerts, pharmacist review and patient- and clinician-facing education to improve awareness and support shared decision-making.
Additional authors were Elizabeth I. Harrison, M.D., of the University of Virginia; Caryn Dutton, M.D., of Beth Israel Deaconess Medical Center and Harvard University; Wesley T. Kerr, M.D., Ph.D., and Scott D. Rothenberger, Ph.D., of Pitt; and Samuel W. Terman, M.D., M.S., of the University of Michigan.
The research received support from the National Institute of Neurological Disorders and Stroke 5K12NS098482-07, NIH K23NS135134, K23NS124656, R25NS089450, U24NS107158), the National Institute on Aging (K23 AG081463), the American Epilepsy Society, the Epilepsy Foundation, the American Academy of Neurology, the American Brain Foundation, the Epilepsy Study Consortium and the UPMC Competitive Medical Research Fund.
Explore the full study and related resources:
Neurology
Contraceptive and Enzyme-Inducing Antiseizure Medication Co-Prescription Among U.S. Medicaid Beneficiaries with Epilepsy
7-Oct-2026