Phenelzine and Pseudoephedrine interaction
Phenelzine and Pseudoephedrine: 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
The potentiation of sympathomimetic substances and related compounds by MAO inhibitors may result in hypertensive crises (see WARNINGS ).
Therefore, patients being treated with phenelzine sulfate should not take sympathomimetic drugs (including amphetamines, cocaine, methylphenidate, dopamine, epinephrine, and norepinephrine) or related compounds (including methyldopa, L-dopa, L-tryptophan, L-tyrosine, and phenylalanine).
Also, they should not be given cocaine or local anesthesia containing sympathomimetic vasoconstrictors.
OTC Medications To Avoid Cold and cough preparations (including those containing dextromethorphan) Nasal decongestants (tablets, drops, or spray) Hay-fever medications Sinus medications Asthma inhalant medications Antiappetite medicines Weight-reducing preparations "Pep" pills L-tryptophan containing preparations Also, certain prescription drugs should be avoided.
From the Pseudoephedrine (Pseudoephedrine hydrochloride) label · effective 2026-05-06
Warnings Do not use if you are now taking a prescription monoamine oxidase inhibitor (MAOI) (certain drugs for depression, psychiatric or emotional conditions, or Parkinson's disease), or for 2 weeks after stopping the MAOI drug.
If you do not know if your prescription drug contains an MAOI, ask a doctor or pharmacist before taking this product.
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.