10/7/2026
A University of Pittsburgh-led study found nearly one-third of Medicaid beneficiaries with epilepsy had overlapping prescriptions that could lower contraceptive effectiveness.
PITTSBURGH — 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 Oct. 7, 2026, in Neurology, the medical journal of the American Academy of Neurology.
Key Takeaways
- A University of Pittsburgh-led study of 110,976 Medicaid beneficiaries with epilepsy found nearly 1 in 5 were prescribed a hormonal contraceptive that could be affected by enzyme-inducing antiseizure medications between 2018 and 2021.
- Among those with a susceptible contraceptive prescription, nearly one-third had at least one overlap of 14 days or longer with an enzyme-inducing antiseizure medication, with a median overlap duration of 218 days.
- People with intellectual disabilities had more than twice the odds of experiencing this prescription overlap, and those with drug-resistant epilepsy or who were age 35 and older also had higher odds and longer overlap periods.
- The study, published in Neurology, was led by senior author Page B. Pennell, M.D., and corresponding author Laura Kirkpatrick, M.D., M.S., both of the University of Pittsburgh School of Medicine, with co-authors from the University of Virginia, Beth Israel Deaconess Medical Center, Harvard University and the University of Michigan.
- Researchers noted that IUDs (intrauterine devices), including hormonal and copper types, are not affected by enzyme-inducing antiseizure medications and may be an option for some patients.
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. 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.
How enzyme-inducing epilepsy drugs can lower birth control effectiveness
Enzyme-inducing antiseizure medications speed up how quickly the body breaks down certain hormones, including those in some contraceptives. That faster breakdown can lower hormone levels enough to reduce how well the birth control method works.
"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."
Medicaid data show months-long prescription overlaps affecting nearly one-third of patients
Using U.S. Medicaid claims data, 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.
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. The median overlap lasted 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."
Which birth control methods may be affected, and which are not
Contraceptive methods that may be affected by enzyme-inducing antiseizure medications include combined birth control pills, progestin-only pills, contraceptive patches, vaginal rings and subdermal implants.
Methods not affected by these medications include hormonal and copper IUDs (intrauterine devices). Co-use of an interacting medication combination may also be appropriate in some circumstances when a patient understands the potential risks and benefits.
This study examined how antiseizure medications may affect contraceptive hormone levels. Separate research has also looked at how some hormonal contraceptives can affect antiseizure medication levels in the opposite direction.
People with intellectual disability faced more than twice the risk of overlapping prescriptions
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. These disparities point to populations that may benefit most from proactive, individualized contraceptive counseling.
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.
Researchers plan to study pregnancy outcomes and ways to flag risky prescription overlaps
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.
Frequently Asked Questions
Q: Can epilepsy medication make birth control less effective?
A: Yes. Certain antiseizure medications, known as enzyme-inducing antiseizure medications, speed up the body's breakdown of contraceptive hormones, which can lower how well some birth control methods work.
Q: Which birth control methods are not affected by epilepsy medication?
A: Hormonal and copper IUDs (intrauterine devices) are not affected by enzyme-inducing antiseizure medications, according to the researchers.
Q: Who is most at risk for this medication overlap?
A: The study found people with intellectual disability had more than twice the odds of experiencing overlapping prescriptions, and those with drug-resistant epilepsy or age who were age 35 and older also had higher odds and longer overlap periods.
Additional Resources
- Contraceptive and Enzyme-Inducing Antiseizure Medication Coprescription Among US Medicaid Beneficiaries With Epilepsy | Neurology
- Common epilepsy medication and birth control combinations may reduce contraceptive effectiveness | EurekAlert!
- UPMC Comprehensive Epilepsy Center: Expert Seizure Care
- Epilepsy | Department of Neurology
- Press contacts: Liz Reid (ReidE4@upmc.edu), Kaleigh Connors (ConnorsKA3@upmc.edu)
Authors and Funding
Authors: Page B. Pennell, M.D., chair of the Department of Neurology at the University of Pittsburgh School of Medicine (senior author); Laura Kirkpatrick, M.D., M.S., assistant professor of pediatrics and neurology at the University of Pittsburgh School of Medicine (corresponding author); 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.
Funding and Disclosures: 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.
