What the FDA labels say about taking them together
Fluoxetine and phenelzine
Phenelzine's FDA label of June 6, 2025 names fluoxetine in its contraindications section; fluoxetine's label does not name phenelzine itself but warns about its class (MAO inhibitors).
Check it at the source: the fluoxetine FDA label on DailyMed (effective January 8, 2026, Dista Products Company); the phenelzine FDA label on DailyMed (effective June 6, 2025, Parke-Davis Div of Pfizer Inc).
What does the fluoxetine label say about phenelzine?
Fluoxetine's label does not name phenelzine itself; it warns about its class (MAO inhibitors):
Fluoxetine label, contraindicationsInhibitors (MAOIs) The use of MAOIs intended to treat psychiatric disorders with PROZAC or within 5 weeks of stopping treatment with PROZAC is contraindicated because of an increased risk of serotonin syndrome.
Fluoxetine label, contraindicationsStarting PROZAC in a patient who is being treated with MAOIs such as linezolid or intravenous methylene blue is also contraindicated because of an increased risk of serotonin syndrome [see Dosage and Administration ( 2.10 ) and Warnings and Precautions ( 5.2 )].
Source: FDA drug label (Prozac), NDA018936 (Eli Lilly And Co), as published by Dista Products Company, effective January 8, 2026 (SPL set c88f33ed-6dfb-4c5e-bc01-d8e36dd97299), via openFDA; the full label on DailyMed
What does the phenelzine label say about fluoxetine?
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
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
| Fluoxetine | Phenelzine | |
|---|---|---|
| Labeled for | Depression, Anxiety, Bipolar disorder | n/a |
| Boxed warning | Yes | Yes |
| Pharmacy cost (NADAC) | $0.0519 per capsule 40 mg capsule | $0.586 per tablet 15 mg tablet |
| 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