Drug interactions
Epinephrine + Thioridazine
Severity: Major
Epinephrine and Thioridazine: major interaction.
Last updated Sources: Health Canada product monograph
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 has alpha-adrenergic blocking activity and can prolong the QT interval, while epinephrine is arrhythmogenic. Together they may produce unopposed beta-mediated vasodilation with hypotension and raise the risk of ventricular arrhythmias.
What this interaction means in plain words
Epinephrine 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.
Epinephrine belongs to Endocrine; Thioridazine belongs to Central Nervous System.
Why it happens
Additive proarrhythmic and QT effects combined with thioridazine alpha-blockade that reverses the pressor effect of epinephrine.
What to do
Avoid combining where possible, and for anaphylaxis use epinephrine as needed with continuous ECG and blood pressure monitoring. If hypotension persists, use a pure vasoconstrictor such as norepinephrine or phenylephrine rather than more epinephrine.
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 Thioridazine
- Abiraterone + Thioridazine Contraindicated
- Adagrasib + Thioridazine Contraindicated
- Amiodarone + Thioridazine Contraindicated
- Amisulpride + Thioridazine Contraindicated
- Amitriptyline + Thioridazine Contraindicated
- Amoxapine + Thioridazine Contraindicated
Other interactions of Epinephrine
- Epinephrine + Isocarboxazid Contraindicated
- Epinephrine + Phenelzine Contraindicated
- Epinephrine + Tranylcypromine Contraindicated
- Acebutolol + Epinephrine Major
- Amitriptyline + Epinephrine Major
- Amoxapine + Epinephrine Major
Frequently asked questions
Can I take Epinephrine with Thioridazine?
MediHelp rates the interaction as major. Epinephrine 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 has alpha-adrenergic blocking activity and can prolong the QT interval, while epinephrine is arrhythmogenic. Together they may produce unopposed beta-mediated vasodilation with hypotension and raise the risk of ventricular arrhythmias.
How serious is the interaction between Epinephrine 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 combining where possible, and for anaphylaxis use epinephrine as needed with continuous ECG and blood pressure monitoring. If hypotension persists, use a pure vasoconstrictor such as norepinephrine or phenylephrine rather than more epinephrine.
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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