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Haloperidol and Methadone: Drug Interaction Guide

Quick answer: This is a major interaction — avoid combining Haloperidol and Methadone unless specifically directed by your doctor.

Interaction severity: Major — avoid combination

How Haloperidol interacts with Methadone

Both drugs prolong the QT interval through blockade of cardiac potassium channels (hERG), additively increasing risk of torsades de pointes.

What you should do

Obtain baseline ECG and electrolytes; avoid combination if QTc >500 ms or in patients with other QT-prolonging risk factors. Monitor ECG periodically if used.

Key facts

Severity

Major — avoid combination

Mechanism

Both drugs prolong the QT interval through blockade of cardiac potassium channels (hERG), additively increasing risk of ...

Action

Obtain baseline ECG and electrolytes; avoid combination if QTc >500 ms or in patients with other QT-prolonging risk fact...

Important medical disclaimer: This page provides educational information about drug interactions for general reference. It is not a substitute for professional medical advice, diagnosis, or treatment. Always discuss your specific medications with a qualified healthcare provider before starting, stopping, or changing any treatment. About our editorial team.

Frequently asked questions

Can I take Haloperidol and Methadone together?

No — this combination should generally be avoided. Obtain baseline ECG and electrolytes; avoid combination if QTc >500 ms or in patients with other QT-prolonging risk factors. Monitor ECG periodically if used.

What is the severity of this interaction?

The interaction between Haloperidol and Methadone is classified as Major — avoid combination. Both drugs prolong the QT interval through blockade of cardiac potassium channels (hERG), additively increasing risk of torsades de pointes.

What should I do if I'm prescribed both?

Obtain baseline ECG and electrolytes; avoid combination if QTc >500 ms or in patients with other QT-prolonging risk factors. Monitor ECG periodically if used. Always consult your prescribing clinician — do not stop or change medications without medical guidance.

Last reviewed: by iMedic Medical Editorial Team. Our editorial process.