Lamotrigine and Valproate Interaction
Drug interaction information between Lamotrigine and Valproate.
Lamotrigine and Valproate have a documented minor interaction in FDA labeling.
FDA drug labeling documents a minor-severity interaction between Lamotrigine and Valproate. This page displays the available source-record category and label text. The category is not an individual risk estimate or medication-combination direction.
How They Interact
Valproate slows down the process your body uses to get rid of lamotrigine, which causes the amount of lamotrigine in your blood to more than double.
FDA Label Information
Valproate ↑ lamotrigine ? valproate Increased lamotrigine concentrations slightly more than 2-fold. There are conflicting study results regarding effect of lamotrigine on valproate concentrations: 1) a mean 25% decrease in valproate concentrations in healthy volunteers, 2) no change in valproate concentrations in controlled clinical trials in patients with epilepsy.
Lamotrigine Also Interacts With
- Dofetilide moderate
- Desmopressin moderate
- Carbamazepine minor
- Rifampin minor
- Phenytoin minor
Valproate Also Interacts With
- Ranitidine major
- Cimetidine major
- Clarithromycin moderate
- Lidocaine Topical moderate
- Risperidone moderate
Frequently Asked Questions
What SPL severity band is on file for Lamotrigine + Valproate?
Compiled FDA labeling labels this pair minor. That is a source-record field, not an individual medication-combination decision.
Which drug in this pair has the larger labeled-interaction portfolio?
Valproate has 41 labeled pairs on file vs Lamotrigine's 24. In the minor band specifically: Lamotrigine has 22 (also Carbamazepine, Rifampin, Phenytoin, Phenobarbital); Valproate has 36 (also Aspirin, Clonazepam, Topiramate, Amitriptyline).
What mechanism field is on file for Lamotrigine and Valproate?
Valproate slows down the process your body uses to get rid of lamotrigine, which causes the amount of lamotrigine in your blood to more than double.
Valproate carries more major-labeled pairs than Lamotrigine
SPL source-record counts only. This page's band is minor · classes on file: Lamotrigine (Anticonvulsant); Valproate (Anticonvulsant / Mood Stabilizer).
Valproate has 2 major-labeled pairs vs Lamotrigine's 0. This page itself is in the minor band, not the major band.
0 major · 2 moderate · 22 minor · 24 total
- Other minor peers for Lamotrigine
- Carbamazepine
- Rifampin
- Phenytoin
- Phenobarbital
2 major · 3 moderate · 36 minor · 41 total
- Other minor peers for Valproate
- Aspirin
- Clonazepam
- Topiramate
- Amitriptyline
Sources: FDA Drug Labels (SPL) via openFDA (2026). This is for informational purposes only and is not medical advice. This registry does not provide individual medication-combination directions.
Read our methodology - how this data is sourced, computed, and verified.