Drug interactions
Doxepin + Moxifloxacin
Severity: Major
Doxepin and Moxifloxacin: major interaction.
Last updated Sources: UK SmPC
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
Doxepin can prolong the QT interval, particularly at antidepressant doses or in overdose, and moxifloxacin has a similar effect. Together they increase the risk of torsades de pointes.
What this interaction means in plain words
Doxepin and Moxifloxacin 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; Moxifloxacin belongs to Anti Bacterial.
Why it happens
Additive pharmacodynamic QT prolongation.
What to do
Prefer a non-QT-prolonging antibiotic. If the combination is needed, monitor ECG and electrolytes, especially with higher doxepin doses.
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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References
- Avelox 400 mg film-coated tablets - SmPC sections 4.3/4.5 (class statement: tricyclic antidepressive agents; "tricyclic antidepressive agents") — electronic medicines compendium (UK SmPC)
Other interactions of Moxifloxacin
- Amiodarone + Moxifloxacin Contraindicated
- Arsenic trioxide + Moxifloxacin Contraindicated
- Disopyramide + Moxifloxacin Contraindicated
- Dofetilide + Moxifloxacin Contraindicated
- Dronedarone + Moxifloxacin Contraindicated
- Droperidol + Moxifloxacin 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 Moxifloxacin?
MediHelp rates the interaction as major. Doxepin and Moxifloxacin 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 can prolong the QT interval, particularly at antidepressant doses or in overdose, and moxifloxacin has a similar effect. Together they increase the risk of torsades de pointes.
How serious is the interaction between Doxepin and Moxifloxacin?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Prefer a non-QT-prolonging antibiotic. If the combination is needed, monitor ECG and electrolytes, especially with higher doxepin doses.
What other medicines interact with Moxifloxacin?
MediHelp also lists interactions of Moxifloxacin with, for example, Amiodarone, Arsenic trioxide, Disopyramide. The full list is on the Moxifloxacin page.
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