Drug interactions
Lisdexamfetamine + Thioridazine
Severity: Major
Lisdexamfetamine and Thioridazine: major 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
Thioridazine strongly prolongs the QT interval and can cause torsades de pointes, while amphetamines cause tachycardia and sympathetic stimulation that may further raise arrhythmic risk. Dopamine blockade by thioridazine also opposes stimulant effects.
What this interaction means in plain words
Lisdexamfetamine and Thioridazine can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Lisdexamfetamine belongs to Central Nervous System; Thioridazine belongs to Central Nervous System.
Why it happens
Additive cardiac risk from thioridazine QT prolongation and amphetamine sympathomimetic effects, plus opposing dopaminergic actions.
What to do
Avoid the combination where possible and choose alternatives with less QT effect. If unavoidable, monitor ECG, electrolytes and heart rate.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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Other interactions of Lisdexamfetamine
- Isocarboxazid + Lisdexamfetamine Contraindicated
- Linezolid + Lisdexamfetamine Contraindicated
- Lisdexamfetamine + Phenelzine Contraindicated
- Lisdexamfetamine + Procarbazine Contraindicated
- Lisdexamfetamine + Rasagiline Contraindicated
- Lisdexamfetamine + Safinamide Contraindicated
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 Lisdexamfetamine with Thioridazine?
MediHelp rates the interaction as major. Lisdexamfetamine and Thioridazine can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Thioridazine strongly prolongs the QT interval and can cause torsades de pointes, while amphetamines cause tachycardia and sympathetic stimulation that may further raise arrhythmic risk. Dopamine blockade by thioridazine also opposes stimulant effects.
How serious is the interaction between Lisdexamfetamine and Thioridazine?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid the combination where possible and choose alternatives with less QT effect. If unavoidable, monitor ECG, electrolytes and heart rate.
What other medicines interact with Lisdexamfetamine?
MediHelp also lists interactions of Lisdexamfetamine with, for example, Isocarboxazid, Linezolid, Phenelzine. The full list is on the Lisdexamfetamine page.
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