Drug interactions
Phendimetrazine + Thioridazine
Severity: Moderate
Phendimetrazine and Thioridazine: 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
Phendimetrazine is a sympathomimetic stimulant that can raise heart rate and blood pressure, and thioridazine prolongs the QT interval. Together they may increase the risk of ventricular arrhythmias, and the stimulant opposes the sedation caused by thioridazine.
What this interaction means in plain words
Phendimetrazine and Thioridazine 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.
Why it happens
Pharmacodynamic opposition and additive proarrhythmic effects of sympathomimetic stimulation with QT prolongation.
What to do
Avoid in patients with cardiac disease, QT prolongation or electrolyte disturbances. Otherwise monitor heart rate, blood pressure and ECG.
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 Thioridazine
- Abiraterone + Thioridazine Contraindicated
- Adagrasib + Thioridazine Contraindicated
- Amiodarone + Thioridazine Contraindicated
- Amisulpride + Thioridazine Contraindicated
- Amitriptyline + Thioridazine Contraindicated
- Amoxapine + Thioridazine Contraindicated
Frequently asked questions
Can I take Phendimetrazine with Thioridazine?
MediHelp rates the interaction as moderate. Phendimetrazine and Thioridazine 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. Phendimetrazine is a sympathomimetic stimulant that can raise heart rate and blood pressure, and thioridazine prolongs the QT interval. Together they may increase the risk of ventricular arrhythmias, and the stimulant opposes the sedation caused by thioridazine.
How serious is the interaction between Phendimetrazine and Thioridazine?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid in patients with cardiac disease, QT prolongation or electrolyte disturbances. Otherwise monitor heart rate, blood pressure and ECG.
What other medicines interact with Thioridazine?
MediHelp also lists interactions of Thioridazine with, for example, Abiraterone, Adagrasib, Amiodarone. The full list is on the Thioridazine page.
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