Drug interactions
Clonidine + Thioridazine
Severity: Major
Clonidine and Thioridazine: major interaction.
Last updated Sources: US FDA label
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
Both lower blood pressure and cause sedation, so together they may produce additive hypotension and drowsiness. Clonidine-induced bradycardia may be particularly undesirable with thioridazine, which strongly prolongs the QT interval and carries torsades risk.
What this interaction means in plain words
Clonidine 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.
Clonidine belongs to Cardiovascular; Thioridazine belongs to Central Nervous System.
Why it happens
Additive hypotension and sedation; bradycardia from clonidine can increase QT-related arrhythmia risk with thioridazine.
What to do
Avoid if possible and choose an alternative antipsychotic or antihypertensive. If combined, monitor ECG, heart rate, blood pressure and electrolytes.
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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References
Other interactions of Clonidine
- Acebutolol + Clonidine Major
- Amifostine + Clonidine Major
- Amiodarone + Clonidine Major
- Amoxapine + Clonidine Major
- Atenolol-chlorthalidone + Clonidine Major
- Atenolol + Clonidine Major
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 Clonidine with Thioridazine?
MediHelp rates the interaction as major. Clonidine 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. Both lower blood pressure and cause sedation, so together they may produce additive hypotension and drowsiness. Clonidine-induced bradycardia may be particularly undesirable with thioridazine, which strongly prolongs the QT interval and carries torsades risk.
How serious is the interaction between Clonidine 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 if possible and choose an alternative antipsychotic or antihypertensive. If combined, monitor ECG, heart rate, blood pressure and electrolytes.
What other medicines interact with Clonidine?
MediHelp also lists interactions of Clonidine with, for example, Acebutolol, Amifostine, Amiodarone. The full list is on the Clonidine page.
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