Epilepsy Meds Can Reduce Birth Control Effectiveness, Increasing Risk Of Unintended Pregnancy

THURSDAY, Oct. 8, 2026 (HealthDay News) — Women with epilepsy, be warned — your antiseizure medications could be interfering with your birth control.

About 1 in 3 women with epilepsy on hormonal birth control have been prescribed an antiseizure drug that can make those contraceptives less effective, researchers reported Oct. 7 in the journal Neurology.

“These were not simply brief or isolated prescription overlaps,” researcher Dr. Laura Kirkpatrick, an assistant professor of pediatrics and neurology at the University of Pittsburgh School of Medicine, said in a news release. “For many people, the overlap continued for months.”

Unintended pregnancies could result from this drug interaction — a concern because pregnancy complications are more common among people with epilepsy, and some epilepsy meds can be harmful to a developing fetus, researchers said.

“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,” senior researcher Dr. Page Pennell, chair of neurology at Pitt’s School of Medicine, said in a news release.

The problem involves enzyme-inducing antiseizure medications, which can accelerate the breakdown of contraceptive hormones and potentially reduce protection against pregnancy, researchers said.

Drugs in this class include carbamazepine, oxcarbazepine, phenobarbital, phenytoin and topiramate, researchers said.

For the new study, researchers dug into U.S. Medicaid claims data to identify nearly 111,000 women of childbearing age who had epilepsy.

Nearly 1 in 5 of the women — around 22,000 — had been prescribed both hormonal birth control and an antiseizure med that could interact with their contraception. Methods of contraception included the pill, patches, vaginal rings and implants.

Results showed that nearly 33% had at least one stretch of 14 days or more when a contraceptive overlapped with an antiseizure drug. These overlaps lasted a median of about seven months, meaning half were longer, half shorter in duration.

Women suffering from an intellectual disability were more than twice as likely to be prescribed such an overlap compared to women without such a disability, researchers found.

Women with drug-resistant epilepsy and those 35 or older also had higher odds of an overlap that could result in pregnancy, researchers found.

Researchers emphasized that women with epilepsy do have birth control options that aren't affected by antiseizure medications.

For example, either hormonal or copper IUDs are not affected by the drugs and should be considered as an option, researchers said.

“It is important for people with epilepsy to know that not all forms of contraception are affected by these medication interactions," Kirkpatrick said. "With informed counseling, people can choose a contraceptive method that aligns with their preferences and health needs.”

The team also noted that their study did not calculate how many unintended pregnancies resulted from these drug interactions.

“Our study did not look at pregnancy outcomes or determine whether participants experienced contraceptive failure, so more research is needed to better understand the real-world impact of these overlapping prescriptions,” Kirkpatrick said.

More information

The Cleveland Clinic has more about antiseizure drugs.

SOURCES: American Academy of Neurology, news release, Oct. 7, 2026; University of Pittsburgh, news release, Oct. 7, 2026