Diltiazem and Carbamazepine Interaction
Drug interaction information between Diltiazem and Carbamazepine.
Diltiazem and Carbamazepine have a documented minor interaction in FDA labeling.
FDA drug labeling documents a minor-severity interaction between Diltiazem and Carbamazepine. 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
Diltiazem slows the liver's ability to process carbamazepine, which can cause the medication to build up to toxic levels.
FDA Label Information
Carbamazepine : Concomitant administration of diltiazem with carbamazepine has been reported to result in elevated serum levels of carbamazepine (40% to 72% increase), resulting in toxicity in some cases.
Diltiazem Also Interacts With
- Ezetimibe major
- Ezetimibe/Simvastatin major
- Simvastatin major
- Theophylline major
- Rifampin moderate
Carbamazepine Also Interacts With
- Nirmatrelvir/Ritonavir major
- Ranolazine major
- Risperidone major
- Lithium moderate
- Apixaban moderate
Frequently Asked Questions
What SPL severity band is on file for Diltiazem + Carbamazepine?
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?
Carbamazepine has 129 labeled pairs on file vs Diltiazem's 46. In the minor band specifically: Diltiazem has 35 (also Buspirone, Pravastatin, Lovastatin, Cyclosporine); Carbamazepine has 110 (also Omeprazole, Ibuprofen, Citalopram, Amitriptyline).
What mechanism field is on file for Diltiazem and Carbamazepine?
Diltiazem slows the liver's ability to process carbamazepine, which can cause the medication to build up to toxic levels.
Diltiazem carries more major-labeled pairs than Carbamazepine
SPL source-record counts only. This page's band is minor · classes on file: Diltiazem (Calcium Channel Blocker); Carbamazepine (Anticonvulsant).
Diltiazem has 4 major-labeled pairs vs Carbamazepine's 3. This page itself is in the minor band, not the major band.
4 major · 7 moderate · 35 minor · 46 total
- Other minor peers for Diltiazem
- Buspirone
- Pravastatin
- Lovastatin
- Cyclosporine
3 major · 16 moderate · 110 minor · 129 total
- Other minor peers for Carbamazepine
- Omeprazole
- Ibuprofen
- Citalopram
- 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.