Phenelzine and Promethazine and codeine interaction
Phenelzine and Promethazine and codeine: both prescribing labels flag this combination with the strongest language, such as a contraindication, a boxed warning, or an instruction to avoid it.
Do not combine without a prescriber's guidance. The label language below is the strongest FDA uses.
What the FDA labels say
From the Phenelzine (phenelzine sulfate) label · effective 2026-05-21
Phenelzine sulfate should not be used in combination with dextromethorphan or with CNS depressants such as alcohol and certain narcotics.
From the Promethazine and codeine (Promethazine Hydrochloride and Codeine Phosphate) label · effective 2025-12-18
Concurrent use of monoamine oxidase inhibitors (MAOIs) or use of MAOIs within 14 days [ see Warnings and Precautions (5.16) , Drug Interactions (7.6) ].
Concurrent use of monoamine oxidase inhibitor (MAOI) therapy or within the last 14 days.
Co-administration with Monoamine Oxidase Inhibitors (MAOIs) Concurrent use of Promethazine HCl and Codeine Phosphate Oral Solution is contraindicated in patients receiving monoamine oxidase inhibitors (MAOIs) or within 14 days of stopping such therapy [ see Contraindications (4) ].
MAOIs may potentiate the effects of morphine, codeine’s active metabolite, including respiratory depression, coma, and confusion MAOIs [ see Drug Interactions (7.6) ].
Serotonergic Drugs : Concomitant use may result in serotonin syndrome.
Taking more than these two? Interactions stack. Check your whole list at once; it stays in your browser.
Open in the checkerNot medical advice. Interaction Checker quotes FDA label text and NIH fact sheets. Whether an interaction matters for you depends on doses, timing, kidney and liver function, and other conditions. Confirm with a pharmacist or prescriber.