Drug interactions
Ethinylestradiol + Lamotrigine
Severity: Major
Ethinylestradiol and Lamotrigine: major interaction.
Last updated Sources: US FDA label
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Ethinylestradiol-containing contraceptives markedly lower lamotrigine concentrations, which may cause breakthrough seizures or mood relapse. Levels can rise during the hormone-free interval and after the contraceptive is stopped, causing toxicity.
What this interaction means in plain words
Ethinylestradiol and Lamotrigine can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Why it happens
Ethinylestradiol induces UGT-mediated glucuronidation of lamotrigine, increasing its clearance.
What to do
Monitor lamotrigine response or levels and increase the dose as needed when starting the contraceptive. Reduce the dose when the contraceptive is stopped, and consider a non-estrogen contraceptive method.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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References
Other interactions of Lamotrigine
Frequently asked questions
Can I take Ethinylestradiol with Lamotrigine?
MediHelp rates the interaction as major. Ethinylestradiol and Lamotrigine can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Ethinylestradiol-containing contraceptives markedly lower lamotrigine concentrations, which may cause breakthrough seizures or mood relapse. Levels can rise during the hormone-free interval and after the contraceptive is stopped, causing toxicity.
How serious is the interaction between Ethinylestradiol and Lamotrigine?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor lamotrigine response or levels and increase the dose as needed when starting the contraceptive. Reduce the dose when the contraceptive is stopped, and consider a non-estrogen contraceptive method.
What other medicines interact with Lamotrigine?
MediHelp also lists interactions of Lamotrigine with, for example, Desogestrel-ethinyl estradiol, Divalproex, Dofetilide. The full list is on the Lamotrigine page.
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