What the FDA labels say about taking them together
Morphine and phenelzine
Morphine's FDA label of July 13, 2026 names phenelzine in its drug interactions section; the phenelzine label PlainMeds reads does not name morphine. The morphine label: “MAOI interactions with opioids may manifest as serotonin syndrome or opioid toxicity.”
Check it at the source: the morphine FDA label on DailyMed (effective July 13, 2026, Bryant Ranch Prepack); the phenelzine FDA label on DailyMed (effective June 6, 2025, Parke-Davis Div of Pfizer Inc).
What does the morphine label say about phenelzine?
Morphine label, drug interactionsMonoamine Oxidase Inhibitors (MAOIs) Clinical Impact: MAOI interactions with opioids may manifest as serotonin syndrome or opioid toxicity (…). Intervention: Do not use morphine sulfate in patients taking MAOIs or within 14 days of stopping such treatment. Examples: phenelzine, tranylcypromine, linezolid
Morphine Sulfate label (Fresenius Kabi, USA LLC, August 31, 2026), drug interactionsMonoamine Oxidase Inhibitors (MAOIs) Clinical Impact: MAOI interactions with opioids may manifest as serotonin syndrome or opioid toxicity (…). … while closely monitoring blood pressure and signs and symptoms of CNS and respiratory depression. Examples: phenelzine, tranylcypromine, linezolid
Source: FDA drug label (Ms Contin, NDA019516), Rhodes Pharmaceuticals LLC, effective August 14, 2026 (SPL set c354b3bf-86c0-4bb8-8b1f-be2164942698), via openFDA
Source: FDA drug label (Morphine Sulfate, NDA204223), Fresenius Kabi, USA LLC, effective August 31, 2026 (SPL set 1f53de80-efc8-4930-b3e3-fba0d026af05), via openFDA
Source: FDA drug label (Morphine Sulfate, NDA022195), Hikma Pharmaceuticals USA Inc., effective February 3, 2026 (SPL set ca359246-4674-4b32-b8b2-673d32b7112f), via openFDA
Source: FDA drug label (Morphine sulfate), ANDA078761 (Sun Pharm Inds Ltd), as published by Bryant Ranch Prepack, effective July 13, 2026 (SPL set 595243fe-a4b1-479a-99d6-a084a4181891), via openFDA; the full label on DailyMed
What does the phenelzine label say about morphine?
Phenelzine's label (effective June 6, 2025) does not name morphine in these sections. A label lists what its studies and reports found; it is not a complete list.
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
| Morphine | Phenelzine | |
|---|---|---|
| Labeled for | Pain | n/a |
| Boxed warning | Yes | Yes |
| Pharmacy cost (NADAC) | $0.226 per tablet 15 mg tablet | $0.586 per tablet 15 mg tablet |
| Shortage now | In shortage | 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