Drug interactions
Doxepin + Levothyroxine
Severity: Moderate
Doxepin and Levothyroxine: 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
Thyroid hormone raises sensitivity to catecholamines, and doxepin, a tricyclic antidepressant, may add to this. The result can be more CNS stimulation and a greater risk of cardiac arrhythmias.
What this interaction means in plain words
Doxepin and Levothyroxine 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.
Doxepin belongs to Dermatology; Levothyroxine belongs to Endocrine.
Why it happens
Thyroid hormone increases adrenergic receptor sensitivity, adding to the noradrenergic effects of the tricyclic antidepressant.
What to do
Monitor heart rate, rhythm and mood when starting or adjusting levothyroxine. Avoid over-replacement of thyroid hormone.
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 Levothyroxine
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 Levothyroxine?
MediHelp rates the interaction as moderate. Doxepin and Levothyroxine 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. Thyroid hormone raises sensitivity to catecholamines, and doxepin, a tricyclic antidepressant, may add to this. The result can be more CNS stimulation and a greater risk of cardiac arrhythmias.
How serious is the interaction between Doxepin and Levothyroxine?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor heart rate, rhythm and mood when starting or adjusting levothyroxine. Avoid over-replacement of thyroid hormone.
What other medicines interact with Levothyroxine?
MediHelp also lists interactions of Levothyroxine with, for example, Cholestyramine, Sodium iodide i-131, Tiratricol. The full list is on the Levothyroxine page.
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