Drug interactions
Doxepin + Ketoconazole
Severity: Major
Doxepin and Ketoconazole: major 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
Both drugs can prolong the QT interval, and ketoconazole may also raise doxepin levels through enzyme inhibition. Together they increase the risk of torsades de pointes and anticholinergic or sedative toxicity.
What this interaction means in plain words
Doxepin and Ketoconazole can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Doxepin belongs to Dermatology; Ketoconazole belongs to Anti Fungals.
Why it happens
Additive QT prolongation with ketoconazole inhibition of CYP3A4 and CYP2C19 metabolism of doxepin.
What to do
Avoid if possible; otherwise obtain a baseline ECG, correct potassium and magnesium, and monitor QTc. Use a lower doxepin dose.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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Other interactions of Ketoconazole
- Alfuzosin + Ketoconazole Contraindicated
- Alprazolam + Ketoconazole Contraindicated
- Avanafil + Ketoconazole Contraindicated
- Conivaptan + Ketoconazole Contraindicated
- Dihydroergotamine intranasal + Ketoconazole Contraindicated
- Dihydroergotamine + Ketoconazole Contraindicated
Other interactions of Doxepin
- Doxepin + Isocarboxazid Contraindicated
- Doxepin + Phenelzine Contraindicated
- Doxepin + Procarbazine Contraindicated
- Doxepin + Safinamide Contraindicated
- Doxepin + Selegiline Contraindicated
- Doxepin + Tranylcypromine Contraindicated
Frequently asked questions
Can I take Doxepin with Ketoconazole?
MediHelp rates the interaction as major. Doxepin and Ketoconazole can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Both drugs can prolong the QT interval, and ketoconazole may also raise doxepin levels through enzyme inhibition. Together they increase the risk of torsades de pointes and anticholinergic or sedative toxicity.
How serious is the interaction between Doxepin and Ketoconazole?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid if possible; otherwise obtain a baseline ECG, correct potassium and magnesium, and monitor QTc. Use a lower doxepin dose.
What other medicines interact with Ketoconazole?
MediHelp also lists interactions of Ketoconazole with, for example, Alfuzosin, Alprazolam, Avanafil. The full list is on the Ketoconazole page.
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