Dapsone Topical and Trimethoprim Interaction
Drug interaction information between Dapsone Topical and Trimethoprim.
Dapsone Topical and Trimethoprim have a documented minor interaction in FDA labeling.
FDA drug labeling documents a minor-severity interaction between Dapsone Topical and Trimethoprim. 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
Trimethoprim can cause dapsone to build up in your body by slowing down how it is cleared out.
FDA Label Information
Trimethoprim/sulfamethoxazole (TMP/SMX) increases the systemic level of dapsone and its metabolites ( 7.1 ). 7.1 Trimethoprim-Sulfamethoxazole A drug-drug interaction study evaluated the effect of the use of dapsone gel, 5% in combination with double strength (160 mg/800 mg) trimethoprim-sulfamethoxazole (TMP/SMX).
Dapsone Topical Also Interacts With
- Acetaminophen moderate
- Nitrofurantoin moderate
- Chloroquine moderate
- Nitroglycerin moderate
- Phenytoin moderate
Trimethoprim Also Interacts With
- Theophylline major
- Prenatal Multivitamin moderate
- Spironolactone moderate
- Spironolactone (Acne) moderate
- Metformin minor
Frequently Asked Questions
What SPL severity band is on file for Dapsone Topical + Trimethoprim?
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?
Trimethoprim has 22 labeled pairs on file vs Dapsone Topical's 10. In the minor band specifically: Dapsone Topical has 4 (also Folic Acid, Rifampin, Benzoyl Peroxide); Trimethoprim has 18 (also Metformin, Glipizide, Warfarin, Methotrexate).
What mechanism field is on file for Dapsone Topical and Trimethoprim?
Trimethoprim can cause dapsone to build up in your body by slowing down how it is cleared out.
Trimethoprim carries more major-labeled pairs than Dapsone Topical
SPL source-record counts only. This page's band is minor · classes on file: Dapsone Topical (Topical Anti-Inflammatory); Trimethoprim (Dihydrofolate Reductase Inhibitor).
Trimethoprim has 1 major-labeled pair vs Dapsone Topical's 0. This page itself is in the minor band, not the major band.
0 major · 6 moderate · 4 minor · 10 total
- Other minor peers for Dapsone Topical
- Folic Acid
- Rifampin
- Benzoyl Peroxide
1 major · 3 moderate · 18 minor · 22 total
- Other minor peers for Trimethoprim
- Metformin
- Glipizide
- Warfarin
- Methotrexate
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.