Mexiletine and Theophylline Interaction
Drug interaction information between Mexiletine and Theophylline.
Mexiletine and Theophylline have a documented minor interaction in FDA labeling.
FDA drug labeling documents a minor-severity interaction between Mexiletine and Theophylline. 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
Mexiletine can slow down the removal of theophylline from your body, which makes the amount of theophylline in your blood go up.
FDA Label Information
Concurrent use of mexiletine and theophylline may lead to increased plasma theophylline levels. One controlled study in eight normal subjects showed a 72% mean increase (range 35 to 136%) in plasma theophylline levels. Theophylline plasma levels returned to pre-mexiletine values within 48 hours after discontinuing mexiletine.
Mexiletine Also Interacts With
- Lidocaine Topical moderate
- Propranolol minor
- Digoxin minor
- Propafenone minor
- Cimetidine minor
Theophylline Also Interacts With
- Metoprolol major
- Albuterol major
- Omeprazole major
- Amoxicillin major
- Famotidine major
Frequently Asked Questions
What SPL severity band is on file for Mexiletine + Theophylline?
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?
Theophylline has 86 labeled pairs on file vs Mexiletine's 14. In the minor band specifically: Mexiletine has 13 (also Propranolol, Digoxin, Propafenone, Cimetidine); Theophylline has 54 (also Propranolol, Methotrexate, Diazepam, Lithium).
What mechanism field is on file for Mexiletine and Theophylline?
Mexiletine can slow down the removal of theophylline from your body, which makes the amount of theophylline in your blood go up.
Theophylline carries more major-labeled pairs than Mexiletine
SPL source-record counts only. This page's band is minor · classes on file: Mexiletine (Class IB Antiarrhythmic); Theophylline (Methylxanthine Bronchodilator).
Theophylline has 27 major-labeled pairs vs Mexiletine's 0. This page itself is in the minor band, not the major band.
0 major · 1 moderate · 13 minor · 14 total
- Other minor peers for Mexiletine
- Propranolol
- Digoxin
- Propafenone
- Cimetidine
27 major · 5 moderate · 54 minor · 86 total
- Other minor peers for Theophylline
- Propranolol
- Methotrexate
- Diazepam
- Lithium
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.