Drug interactions
Doxepin + Haloperidol
Severity: Major
Doxepin and Haloperidol: 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
Both drugs can prolong the QT interval, and haloperidol may raise doxepin levels through CYP2D6 inhibition. This increases the risk of arrhythmia, sedation and anticholinergic effects.
What this interaction means in plain words
Doxepin and Haloperidol 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; Haloperidol belongs to Central Nervous System.
Why it happens
Additive QT prolongation, with haloperidol inhibition of CYP2D6 reducing doxepin clearance.
What to do
Avoid the combination where possible, or use a low doxepin dose. Monitor ECG, electrolytes and sedation.
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
- HALDOL 2 mg/ml oral solution - SmPC sections 4.3/4.5 (class statement: tricyclic antidepressants; "Haloperidol inhibits the metabolism of tricyclic antidepressants (e.g. imipramine, desipramine), thereby increasing plasma concentrations of these medicinal pro") — electronic medicines compendium (UK SmPC)
Other interactions of Haloperidol
- Dofetilide + Haloperidol Contraindicated
- Dronedarone + Haloperidol Contraindicated
- Haloperidol + Ibutilide Contraindicated
- Haloperidol + Levoketoconazole Contraindicated
- Haloperidol + Panobinostat Contraindicated
- Haloperidol + Pimozide 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 Haloperidol?
MediHelp rates the interaction as major. Doxepin and Haloperidol 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 haloperidol may raise doxepin levels through CYP2D6 inhibition. This increases the risk of arrhythmia, sedation and anticholinergic effects.
How serious is the interaction between Doxepin and Haloperidol?
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 the combination where possible, or use a low doxepin dose. Monitor ECG, electrolytes and sedation.
What other medicines interact with Haloperidol?
MediHelp also lists interactions of Haloperidol with, for example, Dofetilide, Dronedarone, Ibutilide. The full list is on the Haloperidol page.
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