Theophylline and Ofloxacin: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Theophylline
Ofloxacin
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
An increased risk of elevated theophylline concentrations
Interaction Deep Dive
The concurrent use of theophylline and ofloxacin may result in an increase in theophylline steady-state levels. Although the clinical significance of this interaction is unclear, theophylline levels should be closely monitored in patients receiving ofloxacin and theophylline doses should be adjusted accordingly. In addition, adverse reactions, including seizures, may occur with or without a corresponding elevation in the serum theophylline levels5.
Why it happens (mechanism)
Inhibition of hepatic clearance of theophylline
Literature reports
4 reports — tap to read
a) Concomitant administration of oral ofloxacin 200 mg twice a day and intravenous theophylline (4.3 mg/kg as a single dose) resulted in no effect on the clearance, half-life, or volume of distribution of the theophylline for seven healthy volunteers 1.
b) Oral ofloxacin treatment for four days caused a mild but statistically significant decrease (12.1%) in theophylline clearance following a single oral theophylline dose in 15 healthy volunteers 2. Also of significance were an increased area under the plasma concentration-time curve (AUC) (9.9%) and an increase in average steady-state plasma concentrations (10.3%). These changes in theophylline pharmacokinetics were considered minor and probably of limited clinical importance.
c) No interaction was observed when oral ofloxacin was given concurrently with aminophylline. Five healthy volunteers were given intravenous infusions of aminophylline 250 mg (theophylline 200 mg) after 200 mg doses of ofloxacin given every eight hours for three consecutive days. In addition, a control period was initiated prior to antibiotic dosing where a single infusion of theophylline was given. Hepatic enzyme activity was evaluated in each subject and no differences were observed between the control period and the active treatment regimens 3.
d) Of the available quinolone antibiotics, enoxacin appears to be the most potent inhibitor of the hepatic clearance of theophylline. Enoxacin consistently decreases theophylline clearance by greater than 50%, while pefloxacin and ciprofloxacin reduce theophylline clearance by 20% to 30%. Only minimal effects on theophylline clearance have been observed with norfloxacin, ofloxacin, and nalidixic acid 4.
Common questions
Can I take Theophylline and Ofloxacin together?
An increased risk of elevated theophylline concentrations Always confirm with your pharmacist or prescriber before making any change.
How serious is the Theophylline and Ofloxacin interaction?
It is rated minor. Usually limited clinical impact.
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 "probable". Good supporting evidence, though not definitively proven.
Questions for your pharmacist
- Does my dose of Theophylline or Ofloxacin 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 anything you'd monitor while I'm on both?
References (5)
- Al-Turk WA, Shaheen OM, Othman S, et al: Effect of ofloxacin on the pharmacokinetics of a single intravenous theophylline dose. Ther Drug Monit 1988; 10:160-163. PubMed
- Gregoire SL, Grasela TH Jr, Freer JP, et al: Inhibition of theophylline clearance by coadministered ofloxacin without alteration of theophylline effects. Antimicrob Agents Chemother 1987; 31:375-378. PubMed
- Sano M, Kawakatsu K, Ohkita C, et al: Effects of enoxacin, ofloxacin and norfloxacin on theophylline disposition in humans. Eur J Clin Pharmacol 1988; 35:161-165. DOI
- Edwards DJ, Bowles SK, Svensson CK, et al: Inhibition of drug metabolism by quinolone antibiotics. Clin Pharmacokinet 1988; 15:194-204. PubMed
- Product Information: Floxin(R), ofloxacin. Ortho-McNeil Pharmaceutical, Inc. aritan, NJ, 2000. DailyMed
Keep reading about Theophylline
Keep reading about Ofloxacin
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