Amitriptyline and Pimozide: 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
Pimozide
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.
These two medicines are not meant to be taken together. Both amitriptyline (Elavil) and pimozide can affect the electrical timing of your heartbeat, something doctors call the QT interval. When you take both, that effect adds up and can raise the risk of a dangerous, irregular heart rhythm.
Because of this, combining them is considered off-limits. The good news is that your care team has safe options. Please don't stop either medicine on your own, but do reach out to your pharmacist or doctor soon so they can review your list and find a safer plan for you.
Contraindicated combination. Both agents prolong the QT interval, so the mechanism is additive QTc prolongation, increasing the risk of torsades de pointes and serious ventricular arrhythmias. This is a pharmacodynamic interaction; neither drug's metabolism is the driver here.
- Direction: additive effect, heightened arrhythmia risk
- Evidence: probable
- Onset: unspecified
Pimozide labeling contraindicates concomitant use with other QT-prolonging drugs and use in patients with hypokalemia or hypomagnesemia. Avoid the combination; select a non-QT-prolonging alternative. If unavoidable, correct electrolytes and obtain ECG monitoring, though avoidance is preferred.
What happens
An increased risk of QT interval prolongation
Interaction Deep Dive
Giving pimozide together with agents known to prolong the QT interval is contraindicated, since such combined use may heighten the likelihood of QT interval prolongation along with serious ventricular arrhythmias. This contraindication likewise applies to patients receiving other medications that prolong the echocardiogram's QT interval, as well as to those with recognized hypokalemia or hypomagnesemia2.
Why it happens (mechanism)
Additive QT interval prolongation
How to manage this interaction
This pairing is generally avoided. Because both drugs can lengthen the QT interval, the usual approach is to not use them together and to choose a safer alternative for one of them.
- Keep taking both exactly as prescribed until you speak with your prescriber. Do not stop suddenly on your own.
- Ask your pharmacist or doctor to review the combination promptly; they may switch one medicine.
- Low potassium or magnesium raises the risk, so your team may check and correct these.
- Report fainting, dizziness, or a racing or irregular heartbeat right away.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
4 reports — tap to read
a) In a controlled study, a single 2 mg dose of pimozide administered together with racemic citalopram 40 mg once daily over 11 days produced a mean rise in QTc values of roughly 10 msec relative to pimozide given by itself. Racemic citalopram did not change the mean AUC or Cmax of pimozide. The mechanism underlying this pharmacodynamic interaction has not been established 2.
b) Case-control studies showed a link between serious ventricular arrhythmias and sudden cardiac death, especially with domperidone doses exceeding 30 mg/day and with domperidone use in patients over 60 years of age 3.
c) In experimental studies involving conditions other than Tourette's Disorder, sudden, unexpected deaths have been reported in patients taking pimozide at doses around 1 mg per kg. A potential mechanism for these deaths is prolongation of the QT interval, which may predispose patients to ventricular arrhythmia. Obtain an electrocardiogram before starting pimozide therapy and at intervals afterward, particularly during the period of dose adjustment 2.
d) Sultopride may cause prolongation of the QT interval and ventricular arrhythmias, including torsades de pointes, after therapeutic or toxic doses 145.
Common questions
Can I take Amitriptyline and Pimozide together?
Amitriptyline and pimozide together can dangerously add to QT prolongation and heart rhythm problems, so this combination is contraindicated. Keep taking both as prescribed for now, but contact your pharmacist or doctor promptly to find a safer option. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Amitriptyline and Pimozide interaction?
It is rated contraindicated. These should generally not be used together.
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 Pimozide interaction managed?
This pairing is generally avoided. Because both drugs can lengthen the QT interval, the usual approach is to not use them together and to choose a safer alternative for one of them. Keep taking both exactly as prescribed until you speak with your prescriber. Do not stop suddenly on your own. Ask your pharmacist or doctor to review the combination promptly; they may switch one medicine. Low potassi… Management is individual — always follow your own care team's guidance.
How strong is the evidence for this interaction?
The evidence is graded "probable". Good supporting evidence, though not definitively proven.
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 Pimozide 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 (5)
- Lande G, Drouin E, Gauthier C, et al: Arrhythmogenic effects of sultopride chlorhydrate: clinical and cellular electrophysiological correlation. Ann Fr Anesth Reanim 1992; 11:629-635.
- Product Information: Pimozide oral tablet, pimozide oral tablet. Endo USA, Inc (per DailyMed), Malvern, PA, 2017. DailyMed
- Teva Canada Limited: Dear Healthcare Professional letter for domperidone maleate. Teva Canada Limited. Toronto, Canada. 2012.
- Montaz L, Varache N, Harry P, et al: Torsades de pointes during sultopride poisoning. J Toxicol Clin Exp 1992; 12:481-496.
- Harry P: Acute poisoning by new psychotropic drugs. Rev Prat 1997; 47:731-735.
Keep reading about Amitriptyline
Keep reading about Pimozide
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