Drug interactions
Itraconazole + Theophylline
Severity: Moderate
Itraconazole and Theophylline: moderate interaction.
Last updated
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
Itraconazole is a strong CYP3A4 inhibitor, but theophylline is mainly cleared by CYP1A2, with CYP3A4 as a minor pathway. Reports suggest a small to modest rise in theophylline levels in some patients, which matters because theophylline has a narrow therapeutic index.
What this interaction means in plain words
Itraconazole 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.
Itraconazole belongs to Anti Fungals; Theophylline belongs to Respiratory.
Why it happens
Inhibition of minor CYP3A4-mediated theophylline metabolism by itraconazole.
What to do
Measure theophylline serum concentration after starting or stopping itraconazole and reduce the dose if levels rise or toxicity signs such as tachycardia, tremor or nausea 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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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 Itraconazole
- Alfuzosin + Itraconazole Contraindicated
- Alprazolam + Itraconazole Contraindicated
- Avanafil + Itraconazole Contraindicated
- Conivaptan + Itraconazole Contraindicated
- Dihydroergotamine intranasal + Itraconazole Contraindicated
- Dihydroergotamine + Itraconazole Contraindicated
Frequently asked questions
Can I take Itraconazole with Theophylline?
MediHelp rates the interaction as moderate. Itraconazole 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. Itraconazole is a strong CYP3A4 inhibitor, but theophylline is mainly cleared by CYP1A2, with CYP3A4 as a minor pathway. Reports suggest a small to modest rise in theophylline levels in some patients, which matters because theophylline has a narrow therapeutic index.
How serious is the interaction between Itraconazole 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: Measure theophylline serum concentration after starting or stopping itraconazole and reduce the dose if levels rise or toxicity signs such as tachycardia, tremor or nausea 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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