What the FDA labels say about taking them together
Fluoxetine and isocarboxazid
Isocarboxazid's FDA label of April 21, 2026 names fluoxetine in its contraindications section; fluoxetine's label does not name isocarboxazid 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 isocarboxazid FDA label on DailyMed (effective April 21, 2026, Lifsa Drugs LLC).
What does the fluoxetine label say about isocarboxazid?
Fluoxetine's label does not name isocarboxazid 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 isocarboxazid label say about fluoxetine?
Isocarboxazid label, contraindicationsThere have been reports of serious, sometimes fatal, reactions (including hyperthermia, rigidity, myoclonus, autonomic instability with possible rapid fluctuations of vital signs, and mental status changes that include extreme agitation and confusion progressing to delirium and coma) in patients receiving fluoxetine (Prozac ® , Lilly) in combination with a monoamine oxidase inhibitor (MAOI), and in patients who have recently discontinued fluoxetine and are then started on a MAOI.
Source: FDA drug label (MARPLAN), Lifsa Drugs LLC, effective April 21, 2026 (SPL set 95fde749-44ad-4668-86c4-0ff17bca0074), 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 | Isocarboxazid | |
|---|---|---|
| Labeled for | Depression, Anxiety, Bipolar disorder | Depression |
| Boxed warning | Yes | Yes |
| Pharmacy cost (NADAC) | $0.0519 per capsule 40 mg capsule | n/a |
| Shortage now | No current entry | In shortage |
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