Amitriptyline and Astemizole: Interaction Details
AI-assisted, pharmacist-reviewed · AI content regenerated Jul 11, 2026 · Source data updated Jul 2, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Amitriptyline
Astemizole
No brand names on record
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
Both amitriptyline (Elavil) and astemizole can affect your heart's electrical rhythm. Each one can stretch out a part of the heartbeat called the QT interval. When you take them together, that effect can add up, which raises the small chance of a dangerous irregular heartbeat.
I want to be honest with you: this concern is based on how these drugs work rather than on studies that tested them together. Still, because the heart is involved, it is taken seriously and combining them is generally not recommended. Please don't change anything on your own. Just talk with your pharmacist or doctor, who can pick a safer option or keep a close eye on your heart.
Effect: Additive QTc prolongation with amitriptyline plus astemizole, increasing risk of torsades de pointes, cardiac arrest.
- Mechanism: Additive pharmacodynamic cardiac effects; both agents delay cardiac repolarization. Neither is a prodrug relevant to this interaction.
- Direction: Increased proarrhythmic risk (additive PD).
- Magnitude/Onset: Not quantified; onset unspecified.
- Evidence: Theoretical; no formal interaction studies. TCAs prolong QTc at therapeutic doses.
- Management: Coadministration not recommended. If unavoidable, use lowest effective dose, correct electrolytes (K+, Mg2+), and monitor ECG/QTc. Prefer an alternative agent.
What happens
An increased risk of cardiotoxicity (QT prolongation, torsades de pointes, cardiac arrest)
Interaction Deep Dive
At the doses recommended for therapy, tricyclic antidepressants are known to lengthen the QTc interval. Although formal studies examining drug interactions have not been conducted, using astemizole together with tricyclic antidepressants or other agents recognized to prolong the QTc interval is not advised23.
Why it happens (mechanism)
Additive cardiac effects
How to manage this interaction
Because both drugs can affect heart rhythm, using them together is generally not recommended. Here is what usually happens and what you can do:
- Your care team may choose a different medication for one of them instead of combining the two.
- If both are truly needed, they may monitor you more closely, including checking your heart with an ECG and reviewing your dose so it can be individualized.
- Keep taking both exactly as prescribed until you have spoken with your prescriber or pharmacist.
- Report fainting, dizziness, or a fluttering/racing heartbeat right away.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
1 report — tap to read
a) A thorough review of how tricyclic antidepressants affect the cardiovascular system has been published 1. In patients taking therapeutic doses of tricyclic antidepressants, the electrocardiogram changes described include a faster heart rate, a lengthened PR interval, delays in intraventricular conduction, a longer corrected QT interval (QTc), and flattened T waves.
Common questions
Can I take Amitriptyline and Astemizole together?
Combining amitriptyline and astemizole can add up their effects on heart rhythm, so this pairing is generally avoided. Don't stop either drug on your own; ask your pharmacist or doctor about a safer alternative or closer heart monitoring. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Amitriptyline and Astemizole interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "unspecified". The timing of this interaction is not well characterized.
How is the Amitriptyline and Astemizole interaction managed?
Because both drugs can affect heart rhythm, using them together is generally not recommended. Here is what usually happens and what you can do: Your care team may choose a different medication for one of them instead of combining the two. If both are truly needed, they may monitor you more closely, including checking your heart with an ECG and reviewing your dose so it can be individualized. Keep… Management is individual — always follow your own care team's guidance.
How strong is the evidence for this interaction?
The evidence is graded "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.
From our Q&A
Real reader questions about these medications, each personally answered by our pharmacist:
Questions for your pharmacist
- Does my dose of Amitriptyline or Astemizole need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there a safer alternative to one of these medications for me?
References (3)
- Marshall JB & Forker AD: Cardiovascular effects of tricyclic antidepressant drugs: therapeutic usage, overdose, and management of complications. Am Heart J 1982; 103:401-414. PubMed
- Product Information: Elavil(R), amitriptyline. Merck & Co, Inc, West Point, PA, 1999. DailyMed
- Product Information: Hismanal(R), astemizole. Janssen Pharmaceutica, Inc. Titusville, NJ, 1996.
Keep reading about Amitriptyline
Keep reading about Astemizole
These medications also interact with supplements
Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:
major · moderate · minor — check everything you take with our drug–supplement interaction checker.
Check another combination
Our instant two-drug interaction checker is almost here.
Still have questions about this combination?
Every question gets a real answer from a licensed pharmacist — free, and usually within a day.
Ask the pharmacist