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Many anticonvulsant medications interact with contraceptive hormones. Anticonvulsants are increasingly used for psychiatric illness, chronic pain, fibromyalgia, and migraine prevention (as well as seizures). Due to the risk of fetal anomalies with these medications, contraceptive counseling is particularly important for woman taking anticonvulsants.

Carbamazepine, oxcarbazepine, barbiturates, primidone, phenytoin, and topiramate trigger hepatic metabolism of estrogen and progestin, raising the risk of contraceptive failure. For this reason, estrogen/progestin pills, patch, and ring get a “3” rating from WHO/CDC, meaning that these methods should be selected only if another method is inappropriate. If a combination pill is the best choice, a higher-estrogen pill (containing 30 or 35 mcg estrogen) may help lower the risk of pregnancy. Because progestin-only pills and implants may be less effective for women taking non-lamotrigine anticonvulsants, these methods get a “3” and a “2” rating, respectively. Depo has a high enough progestin dose that its efficacy is not compromised by anticonvulsants. Women taking anticonvulsants may use progestin injection or an IUD without restrictions.

Lamotrigine is an exception to the general rule about anticonvulsants’ interactions with hormones. Oral contraceptive pills can lower lamotrigine concentrations, which may impair seizure control. For this reason, women taking lamotrigine alone for seizures should be steered away from estrogen/progestin pills, patch, and ring. Women who take lamotrigine alone for other purposes may find that they need to adjust their lamotrigine dose while on estrogen-containing contraceptives. However, for women taking lamotrigine and valproate, estrogen/progestin methods carry no extra caution. Women taking lamotrigine can use all non-estrogen contraceptives without restrictions. To prevent unintended pregnancy, fetal anomalies, and seizures, women taking anticonvulsants should get thorough and accurate contraceptive counseling.

Medical Eligibility Chart for Drug Interactions:

We appreciate your feedback! Please write to us at pearls@reproductiveaccess.org with any questions, comments or additional resources to add to our list.

Helpful Resources

Your Birth Control Choices 

Medical Eligibility for Initiating Contraception

Sources

Bonnema RA, McNamara MC, Spencer AL. Contraception choices in women with underlying medical conditions. American Academy of Family Physicians. Sep 2010. 82(6); 621-628. 

McDonagh M, Peterson K, Lee N, et al. Introduction. In: McDonagh M, Peterson K, Lee N, et al. Drug Class Review: Antiepileptic Drugs for Indications Other Than Epilepsy: Final Report Update 2: Oregon Health & Science University; Oct 2008.

Free CME Credit

To earn 1 free CME credit, all you have to do is take a short quiz based on the content in this month’s Contraceptive Pearl. Answer 2 of the 3 questions correctly, and you’ll receive a certificate documenting your CME credit. It’s that easy! CME granted by the American Academy of Family Physicians.

Just click on this CME Quiz and get started!

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The Reproductive Health Access Project does not accept funding from pharmaceutical companies. We do not promote specific brands of medication or contraception. The information in the Contraceptive Pearls is unbiased, based on science alone.