What the FDA labels say about taking them together
Phenelzine and venlafaxine
Phenelzine's FDA label of June 6, 2025 names venlafaxine in its contraindications section; venlafaxine's label does not name phenelzine itself but warns about its class (MAO inhibitors).
Check it at the source: the phenelzine FDA label on DailyMed (effective June 6, 2025, Parke-Davis Div of Pfizer Inc); the venlafaxine FDA label on DailyMed (effective August 15, 2023, Viatris Specialty LLC).
What does the phenelzine label say about venlafaxine?
Phenelzine label, contraindicationsThere 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.
Phenelzine label, drug interactionsDrug 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.
Source: FDA drug label (Nardil), Parke-Davis Div of Pfizer Inc, effective June 6, 2025 (SPL set 513a41d0-37d4-4355-8a6d-a2c643bce6fa), via openFDA; the full label on DailyMed
What does the venlafaxine label say about phenelzine?
Venlafaxine's label does not name phenelzine itself; it warns about its class (MAO inhibitors):
Venlafaxine label, contraindicationsCONTRAINDICATIONS Venlafaxine Extended-Release Tablets are contraindicated in patients: with known hypersensitivity to venlafaxine besylate, venlafaxine hydrochloride, desvenlafaxine succinate or to any excipients in Venlafaxine Extended-Release Tablets [see Adverse Reactions ( 6.2 )]. taking, or within 14 days of stopping, MAOIs (including the MAOIs linezolid and intravenous methylene blue) because of increased risk of serotonin syndrome [see Dosage and Administration ( 2.9 ), Warnings and Precautions ( 5.2 ) …
Venlafaxine label, contraindicationsInhibitors (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.
Source: FDA drug label (Effexor XR), NDA020699 (Upjohn), as published by Viatris Specialty LLC, effective August 15, 2023 (SPL set c848a5d8-ba94-4c84-80e3-0bf35fb8e32e), via openFDA; the full label on DailyMed
These are the labels' own sentences. PlainMeds does not grade interactions; a pharmacist or prescriber can say what they mean for one person's medicines.
Both medicines on the record
| Phenelzine | Venlafaxine | |
|---|---|---|
| Labeled for | n/a | Depression, Anxiety |
| Boxed warning | Yes | Yes |
| Pharmacy cost (NADAC) | $0.586 per tablet 15 mg tablet | $0.0799 per capsule 75 mg capsule |
| Shortage now | No current entry | No current entry |
Source: FDA NDC Directory, CMS NADAC of October 7, 2026 and the FDA Drug Shortage Database (FDA files October 8, 2026)
What next?
- Check more medicines together
- up to five at once