Drug interactions
Ketoconazole + Theophylline
Severity: Moderate
Ketoconazole 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
Ketoconazole may modestly raise theophylline levels, although some studies show little change. Theophylline toxicity may occur in susceptible patients.
What this interaction means in plain words
Ketoconazole 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.
Ketoconazole belongs to Anti Fungals; Theophylline belongs to Respiratory.
Why it happens
Ketoconazole inhibits CYP3A4, a minor pathway of theophylline metabolism.
What to do
Monitor serum theophylline concentrations when starting or stopping ketoconazole. Reduce the theophylline dose if levels rise or toxicity symptoms appear.
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 Ketoconazole
- Alfuzosin + Ketoconazole Contraindicated
- Alprazolam + Ketoconazole Contraindicated
- Avanafil + Ketoconazole Contraindicated
- Conivaptan + Ketoconazole Contraindicated
- Dihydroergotamine intranasal + Ketoconazole Contraindicated
- Dihydroergotamine + Ketoconazole Contraindicated
Frequently asked questions
Can I take Ketoconazole with Theophylline?
MediHelp rates the interaction as moderate. Ketoconazole 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. Ketoconazole may modestly raise theophylline levels, although some studies show little change. Theophylline toxicity may occur in susceptible patients.
How serious is the interaction between Ketoconazole 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 serum theophylline concentrations when starting or stopping ketoconazole. Reduce the theophylline dose if levels rise or toxicity symptoms appear.
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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