What the FDA labels say about taking them together
Codeine and phenelzine
Codeine's FDA label of December 22, 2025 names phenelzine in its drug interactions section; the phenelzine label PlainMeds reads does not name codeine. The codeine label: “MAOI interactions with opioids may manifest as serotonin syndrome or opioid toxicity.”
Check it at the source: the codeine FDA label on DailyMed (effective December 22, 2025, Hikma Pharmaceuticals USA Inc.); the phenelzine FDA label on DailyMed (effective June 6, 2025, Parke-Davis Div of Pfizer Inc).
What does the codeine label say about phenelzine?
Codeine label, 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 (Codeine sulfate), Hikma Pharmaceuticals USA Inc., effective December 22, 2025 (SPL set 010905f9-3bcb-4b50-9fe8-a3ad0010f14c), via openFDA; the full label on DailyMed
What does the phenelzine label say about codeine?
Phenelzine's label (effective June 6, 2025) does not name codeine 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
| Codeine | Phenelzine | |
|---|---|---|
| Labeled for | Pain | n/a |
| Boxed warning | Yes | Yes |
| Pharmacy cost (NADAC) | $0.726 per tablet 30 mg tablet | $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