Lamotrigine and Valproate: Drug Interaction Guide
Quick answer: This is a major interaction — avoid combining Lamotrigine and Valproate unless specifically directed by your doctor.
How Lamotrigine interacts with Valproate
Valproate inhibits UGT1A4-mediated glucuronidation of lamotrigine, more than doubling its plasma levels and substantially increasing risk of severe rash including Stevens-Johnson syndrome.
What you should do
Use halved lamotrigine starting dose (12.5-25 mg every other day) and slower titration when combined with valproate; counsel on rash.
Key facts
Severity
Major — avoid combination
Mechanism
Valproate inhibits UGT1A4-mediated glucuronidation of lamotrigine, more than doubling its plasma levels and substantiall...
Action
Use halved lamotrigine starting dose (12.5-25 mg every other day) and slower titration when combined with valproate; cou...
Frequently asked questions
Can I take Lamotrigine and Valproate together?
No — this combination should generally be avoided. Use halved lamotrigine starting dose (12.5-25 mg every other day) and slower titration when combined with valproate; counsel on rash.
What is the severity of this interaction?
The interaction between Lamotrigine and Valproate is classified as Major — avoid combination. Valproate inhibits UGT1A4-mediated glucuronidation of lamotrigine, more than doubling its plasma levels and substantially increasing risk of severe rash including Stevens-Johnson syndrome.
What should I do if I'm prescribed both?
Use halved lamotrigine starting dose (12.5-25 mg every other day) and slower titration when combined with valproate; counsel on rash. Always consult your prescribing clinician — do not stop or change medications without medical guidance.
Last reviewed: by iMedic Medical Editorial Team. Our editorial process.