Drug interactions
Amitriptyline + Levothyroxine
Severity: Moderate
Amitriptyline 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 may increase sensitivity to the effects of tricyclic antidepressants, and combined use has been associated with tachycardia and arrhythmias. Antidepressant response may also be accelerated, but toxicity may emerge more readily, particularly in patients with excess thyroid hormone.
What this interaction means in plain words
Amitriptyline 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.
Amitriptyline belongs to Central Nervous System; Levothyroxine belongs to Endocrine.
Why it happens
Thyroid hormone increases beta-adrenergic receptor sensitivity, adding to tricyclic noradrenergic and cardiac effects.
What to do
Monitor heart rate, rhythm and thyroid function, and avoid over-replacement with levothyroxine. Watch for tricyclic toxicity and ECG changes in patients with cardiac disease.
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?
Pro+ members
Unlock the full page
Create an account and start a Pro+ trial to unlock the full management advice for Amitriptyline and Levothyroxine, the additional notes, the evidence detail and the whole-prescription interaction checker.
- Full clinical management advice
- Additional notes
- Evidence detail
- Interaction checker for a whole prescription
Try Pro+ free for 14 days on the web. No card needed.
Other interactions of Amitriptyline
- Amitriptyline + Isocarboxazid Contraindicated
- Amitriptyline + Methylene blue Contraindicated
- Amitriptyline + Phenelzine Contraindicated
- Amitriptyline + Pimozide Contraindicated
- Amitriptyline + Procarbazine Contraindicated
- Amitriptyline + Safinamide Contraindicated
Other interactions of Levothyroxine
Frequently asked questions
Can I take Amitriptyline with Levothyroxine?
MediHelp rates the interaction as moderate. Amitriptyline 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 may increase sensitivity to the effects of tricyclic antidepressants, and combined use has been associated with tachycardia and arrhythmias. Antidepressant response may also be accelerated, but toxicity may emerge more readily, particularly in patients with excess thyroid hormone.
How serious is the interaction between Amitriptyline 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 thyroid function, and avoid over-replacement with levothyroxine. Watch for tricyclic toxicity and ECG changes in patients with cardiac disease.
What other medicines interact with Amitriptyline?
MediHelp also lists interactions of Amitriptyline with, for example, Isocarboxazid, Methylene blue, Phenelzine. The full list is on the Amitriptyline page.
Full monographs, dosing and an interaction checker in the MediHelp app
Open the complete reference, check multi-drug interactions and use dosing tools in the MediHelp app.
