Nearly one in three people with epilepsy who were prescribed certain hormonal contraceptives were also prescribed antiseizure medications that can make those contraceptives less effective, according to a University of Pittsburgh-led study published October 7 in Neurology, the journal of the American Academy of Neurology, and reported by News-Medical and MedicalXpress.
Using United States Medicaid claims data from 2018 to 2021, 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. The methods included combined and progestin-only pills, contraceptive patches, vaginal rings and subdermal implants.
The interaction is well established in pharmacology but, the study suggests, easy to miss in busy practice. A subset of antiseizure medications speeds up the activity of liver enzymes that clear steroid hormones from the body. When those drugs are taken alongside hormonal contraceptives that depend on sustained hormone levels, the contraceptive hormones are broken down faster, blood levels fall, and protection against pregnancy can be reduced without any obvious warning sign.
The stakes are higher than a routine prescribing clash. People with epilepsy can face additional risks during pregnancy, and some antiseizure medications have been linked to risks for a developing baby. An unplanned pregnancy can also remove the chance to adjust medications in advance and to begin folic acid supplementation before conception, steps that require planning. Study author Laura Kirkpatrick of the University of Pittsburgh School of Medicine said the findings suggest many people may be prescribed combinations that could raise the risk of unintended pregnancy.
Senior author Page B. Pennell, chair of neurology at Pitts School of Medicine, said patients may not realize that some antiseizure medications can interact with some forms of hormonal contraception. The researchers emphasized coordinated conversations among neurologists, reproductive health clinicians, pharmacists and patients so that medication and contraceptive choices reflect each persons health needs and reproductive goals.
The study examined prescribing records, not pregnancy outcomes, so it shows how often the risky combination was prescribed rather than how often contraception actually failed. Even so, the authors say the scale of the overlap makes it worth addressing in routine care. This report is general information about published research, not medical advice. Anyone who uses antiseizure medication and hormonal contraception and is concerned about an interaction should not stop either medication on their own and should raise the question promptly with their prescribing clinician or pharmacist.
The gap the study exposes is partly a communication problem built into modern care. A neurologist managing seizures, a primary care clinician renewing contraception and a pharmacist dispensing both may each see only part of the picture, and electronic records do not always flag this particular interaction with the urgency it deserves. The researchers found the overlap across pills, patches, rings and implants, which means counseling has to cover the full menu of hormonal options rather than a single product.
Alternatives exist, including contraceptive methods that are not meaningfully affected by enzyme-inducing medications and antiseizure drugs that do not induce those enzymes, but choosing among them involves seizure history, side effects, cost and personal preference. That trade-off is exactly why the authors call for shared decision-making rather than a blanket rule. Their point is not that any individual prescription was wrong, but that nearly one in three overlapping prescriptions represents a conversation the system should make routine: what each drug does to the other, what the plan is if pregnancy is desired later, and who checks again when either medication changes.
