Does Lamotrigine Interact With Valproic Acid?

Use this combination with caution. Your prescriber may monitor you more closely or adjust doses.

Interactions like this one can happen when two medicines have overlapping effects, or when one changes how the other is absorbed, broken down, or cleared from the body. Lamotrigine is a anticonvulsant / mood stabilizer and Valproic Acid is a anticonvulsant / mood stabilizer; together they are documented as a moderate interaction. How much this matters depends on your dose, your other medications, and your overall health.

If you have been prescribed both Lamotrigine and Valproic Acid, do not start, stop, or change either medication on your own — some medicines are unsafe to stop suddenly. Tell your prescriber and pharmacist that you take both so they can decide whether the combination is right for you, adjust the dose, monitor you more closely, or suggest an alternative.

In addition to age, factors that may increase the risk of occurrence or the severity of rash caused by lamotrigine include (1) coadministration of lamotrigine with valproate (includes valproic acid and divalproex sodium), (2) exceeding the recommended initial dose of lamotrigine, (3) exceeding the recommended dose escalation for lamotrigine, or (4) the presence of the HLA-B*1502 allele However, cases have occurred in the absence of these factors.

Source: FDA structured product labeling (set_id 003663e5-c0c7-4fc1-a64d-313f2a5b10d2).