Dosing Lamotrigine with Birth Control

Key Interactions Between Lamotrigine and Contraceptives

When lamotrigine is used with combined hormonal contraceptives (CHCs), the lamotrigine dose will likely need to be increased by approximately 50-100% due to significant reduction in lamotrigine plasma levels caused by CHCs, as recommended by the U.S. Medical Eligibility Criteria for Contraceptive Use 1
The U.S. Medical Eligibility Criteria for Contraceptive Use classifies the interaction between lamotrigine and CHCs as Category 3 (risks generally outweigh benefits), with a significant reduction in lamotrigine plasma levels by >50% requiring dose adjustments 1, 2, 3
Pharmacokinetic studies show lamotrigine levels decrease significantly during CHC use, potentially leading to increased seizure activity, with the American College of Obstetricians and Gynecologists recommending close monitoring 1
This interaction occurs only with lamotrigine monotherapy; combinations with non-enzyme-inducing antiepileptics (like sodium valproate) may not have the same interaction, according to the American Academy of Neurology 1

Progestin-only pills (POPs), depot medroxyprogesterone acetate (DMPA), and implants do not significantly interact with lamotrigine, and are classified as Category 1 (no restrictions) for use with lamotrigine by the U.S. Medical Eligibility Criteria for Contraceptive Use 4
Copper IUDs and levonorgestrel IUDs are classified as Category 1 (no restrictions) for use with lamotrigine, with no reported interactions, as stated by the American College of Obstetricians and Gynecologists 4, 5
The Centers for Disease Control and Prevention recommends considering these non-CHC methods to avoid complex dosing adjustments and potential seizure breakthrough or mood destabilization that can occur with CHC-lamotrigine interactions 4

The Centers for Disease Control and Prevention (CDC) explicitly classifies lamotrigine as Category 1 (no restrictions) for use with all barrier methods, fertility awareness methods, and when no contraception is used, indicating that lamotrigine poses no health risks related to contraceptive status 6, 7
The CDC also notes that lamotrigine does not interact with progestin-only contraceptives, DMPA injections, or implants, and no drug interactions have been reported with copper IUDs or levonorgestrel IUDs, demonstrating the drug's safety profile is independent of hormonal contraceptive use 6
If a patient on lamotrigine later decides to start combined hormonal contraceptives, the combined hormonal contraceptives will reduce lamotrigine plasma levels by more than 50%, requiring a 50-100% dose increase of lamotrigine, according to the CDC 8

The American College of Obstetricians and Gynecologists and the CDC recommend that patients on lamotrigine be counseled about the potential interaction with combined hormonal contraceptives, and that lamotrigine dosing may need adjustment and close monitoring for efficacy if combined hormonal contraceptives are initiated 6, 7