Drug interactions
Granisetron + Phenelzine
Severity: Major
Granisetron and Phenelzine: 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
Serotonin syndrome has been reported with 5-HT3 antagonists given with serotonergic agents. Phenelzine is a nonselective MAO inhibitor that markedly increases serotonin availability, so adding granisetron may raise the risk of toxicity. The risk is likely small but the outcome can be severe.
What this interaction means in plain words
Granisetron and Phenelzine 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.
Granisetron belongs to Gastrointestinal Tract; Phenelzine belongs to Central Nervous System.
Why it happens
Additive serotonergic pharmacodynamic effect on top of irreversible MAO inhibition.
What to do
Use a non-serotonergic antiemetic where possible. If granisetron is needed, monitor closely for neuromuscular excitability, autonomic instability and altered mental state, and stop it if symptoms appear.
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 Granisetron
- Apomorphine + Granisetron Contraindicated
- Amiodarone + Granisetron Major
- Amisulpride + Granisetron Major
- Arsenic trioxide + Granisetron Major
- Artemether / lumefantrine + Granisetron Major
- Artemether + Granisetron Major
Other interactions of Phenelzine
- 5-HTP + Phenelzine Contraindicated
- Amitriptyline + Phenelzine Contraindicated
- Amoxapine + Phenelzine Contraindicated
- Atomoxetine + Phenelzine Contraindicated
- Benzphetamine + Phenelzine Contraindicated
- Brimonidine + Phenelzine Contraindicated
Frequently asked questions
Can I take Granisetron with Phenelzine?
MediHelp rates the interaction as major. Granisetron and Phenelzine 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. Serotonin syndrome has been reported with 5-HT3 antagonists given with serotonergic agents. Phenelzine is a nonselective MAO inhibitor that markedly increases serotonin availability, so adding granisetron may raise the risk of toxicity. The risk is likely small but the outcome can be severe.
How serious is the interaction between Granisetron and Phenelzine?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Use a non-serotonergic antiemetic where possible. If granisetron is needed, monitor closely for neuromuscular excitability, autonomic instability and altered mental state, and stop it if symptoms appear.
What other medicines interact with Granisetron?
MediHelp also lists interactions of Granisetron with, for example, Apomorphine, Amiodarone, Amisulpride. The full list is on the Granisetron page.
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