Levofloxacin and Theophylline: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Theophylline
Levofloxacin
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
What happens
Theophylline toxicity (nausea, vomiting, palpitations, seizures)
Interaction Deep Dive
Levofloxacin did not have a significant effect on the plasma concentrations, area under the plasma concentration-time curve (AUC), and other disposition parameters for theophylline in a study involving 14 healthy volunteers. No effect of theophylline on levofloxacin absorption and disposition was observed. Other quinolones, however, have resulted in prolonged theophylline elimination half-life, elevated serum theophylline levels, and an increase in the risk of theophylline related adverse reactions. Therefore, theophylline levels should be closely monitored and appropriate dosage adjustments made when levofloxacin is coadministered. Adverse reactions including seizures, may occur with or without an elevation in serum theophylline levels1.
Why it happens (mechanism)
Decreased clearance of theophylline
Common questions
Can I take Levofloxacin and Theophylline together?
Theophylline toxicity (nausea, vomiting, palpitations, seizures) Always confirm with your pharmacist or prescriber before making any change.
How serious is the Levofloxacin and Theophylline interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "delayed". Effects tend to build up gradually over days to weeks.
How strong is the evidence for this interaction?
The evidence is graded "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.
Questions for your pharmacist
- Does my dose of Levofloxacin or Theophylline need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there a safer alternative to one of these medications for me?
References (1)
- Product Information: Levaquin(R), levofloxacin. Ortho-McNeil Pharmaceutical, Inc. Raritan, NJ, 2003. DailyMed
Keep reading about Theophylline
Keep reading about Levofloxacin
These medications also interact with supplements
Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:
major · moderate · minor — check everything you take with our drug–supplement interaction checker.
Check another combination
Our instant two-drug interaction checker is almost here.
Still have questions about this combination?
Every question gets a real answer from a licensed pharmacist — free, and usually within a day.
Ask the pharmacist