Drug interactions
Doxepin + Nortriptyline
Severity: Major
Doxepin and Nortriptyline: major 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
Combining two tricyclic antidepressants increases additive anticholinergic, sedative, serotonergic and QT-prolonging effects. Doxepin is also metabolized by CYP2D6, and competition may increase concentrations of both.
What this interaction means in plain words
Doxepin and Nortriptyline 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; Nortriptyline belongs to Central Nervous System.
Why it happens
Additive pharmacodynamic effects and competition for CYP2D6 and CYP2C19 metabolism.
What to do
Avoid concurrent use of two tricyclics. If a switch is needed, taper and cross over with ECG and symptom monitoring.
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
Other interactions of Nortriptyline
- Disopyramide + Nortriptyline Contraindicated
- Dofetilide + Nortriptyline Contraindicated
- Dronedarone + Nortriptyline Contraindicated
- Ibutilide + Nortriptyline Contraindicated
- Isocarboxazid + Nortriptyline Contraindicated
- Methylene blue + Nortriptyline 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 Nortriptyline?
MediHelp rates the interaction as major. Doxepin and Nortriptyline 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. Combining two tricyclic antidepressants increases additive anticholinergic, sedative, serotonergic and QT-prolonging effects. Doxepin is also metabolized by CYP2D6, and competition may increase concentrations of both.
How serious is the interaction between Doxepin and Nortriptyline?
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 concurrent use of two tricyclics. If a switch is needed, taper and cross over with ECG and symptom monitoring.
What other medicines interact with Nortriptyline?
MediHelp also lists interactions of Nortriptyline with, for example, Disopyramide, Dofetilide, Dronedarone. The full list is on the Nortriptyline page.
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