Drug interactions
Metronidazole + Theophylline
Severity: Moderate
Metronidazole and Theophylline: moderate interaction.
Last updated Sources: US FDA label
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Metronidazole has been reported to increase theophylline concentrations in some patients, with a risk of toxicity. The effect is variable.
What this interaction means in plain words
Metronidazole and Theophylline can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Metronidazole belongs to Anti Parasitic; Theophylline belongs to Respiratory.
Why it happens
Metronidazole may inhibit hepatic metabolism of theophylline.
What to do
Monitor theophylline levels and toxicity signs during metronidazole treatment, and reduce the dose if concentrations rise.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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References
- Theophylline (Anhydrous) - FDA drug label (DailyMed) — openFDA / DailyMed
Other interactions of Theophylline
- Riociguat + Theophylline Contraindicated
- Adenosine + Theophylline Major
- Apalutamide + Theophylline Major
- Bupropion + Theophylline Major
- Carvedilol + Theophylline Major
- Cimetidine + Theophylline Major
Other interactions of Metronidazole
- Ethanol + Metronidazole Contraindicated
- Metronidazole + Pimozide Contraindicated
- Amiodarone + Metronidazole Major
- Disulfiram + Metronidazole Major
- Ergotamine + Metronidazole Major
- Lomitapide + Metronidazole Major
Frequently asked questions
Can I take Metronidazole with Theophylline?
MediHelp rates the interaction as moderate. Metronidazole and Theophylline can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Metronidazole has been reported to increase theophylline concentrations in some patients, with a risk of toxicity. The effect is variable.
How serious is the interaction between Metronidazole and Theophylline?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor theophylline levels and toxicity signs during metronidazole treatment, and reduce the dose if concentrations rise.
What other medicines interact with Theophylline?
MediHelp also lists interactions of Theophylline with, for example, Riociguat, Adenosine, Apalutamide. The full list is on the Theophylline page.
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