Phenelzine and Venlafaxine interaction
Phenelzine and Venlafaxine: both prescribing labels flag this combination with the strongest language, such as a contraindication, a boxed warning, or an instruction to avoid it.
Do not combine without a prescriber's guidance. The label language below is the strongest FDA uses.
What the FDA labels say
From the Phenelzine (phenelzine sulfate) label · effective 2026-05-21
There have been reports of serious reactions (including hyperthermia, rigidity, myoclonic movements and death) when serotoninergic drugs (e.g., dexfenfluramine, fluoxetine, fluvoxamine, paroxetine, sertraline, citalopram, venlafaxine) have been combined with an MAO inhibitor.
Drug Interactions In patients receiving nonselective monoamine oxidase (MAO) inhibitors in combination with serotoninergic agents (e.g., dexfenfluramine, fluoxetine, fluvoxamine, paroxetine, sertraline, citalopram, venlafaxine) there have been reports of serious, sometimes fatal, reactions.
Anyone considering the use of phenelzine sulfate or any other antidepressant in a child, adolescent, or young adult must balance this risk with the clinical need.
At least 14 days should elapse between the discontinuation of phenelzine sulfate and the institution of another antidepressant or buspirone HCl, or the discontinuation of another MAO inhibitor and the institution of phenelzine sulfate.
Concomitant Use with Dibenzazepine Derivative Drugs If the decision is made to administer phenelzine sulfate concurrently with other antidepressant drugs, or within less than 10 days after discontinuation of antidepressant therapy, the patient should be cautioned by the physician regarding the possibility of adverse drug interaction.
From the Venlafaxine (Venlafaxine Hydrochloride) label · effective 2025-01-31
Anyone considering the use of Venlafaxine Extended Release Tablets or any other antidepressant in a child, adolescent, or young adult must balance this risk with the clinical need.
Serotonin Syndrome and MAOIs: Do not use MAOI’s intended to treat psychiatric disorders with Venlafaxine Extended Release Tablets or within 7 days of stopping treatment with Venlafaxine Extended Release Tablets.
Do not use Venlafaxine Extended Release Tablets within 14 days of stopping an MAOI intended to treat psychiatric disorders.
Monoamine Oxidase Inhibitors (MAOIs) The use of MAOI’s intended to treat psychiatric disorders with Venlafaxine Extended Release Tablets or within 7 days of stopping treatment with Venlafaxine Extended Release Tablets is contraindicated because of an increased risk of serotonin syndrome.
The use of Venlafaxine Extended Release Tablets within 14 days of stopping, an MAOI intended to treat psychiatric disorders is also contraindicated [see Dosage and Administration ( 2.6 ), and Warnings and Precautions ( 5.2 )] .
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Open in the checkerNot medical advice. Interaction Checker quotes FDA label text and NIH fact sheets. Whether an interaction matters for you depends on doses, timing, kidney and liver function, and other conditions. Confirm with a pharmacist or prescriber.