Phenylephrine and Tranylcypromine Interaction
Drug interaction information between Phenylephrine and Tranylcypromine.
Phenylephrine and Tranylcypromine have a documented major interaction in FDA labeling.
FDA drug labeling documents a major-severity interaction between Phenylephrine and Tranylcypromine. Major interactions are generally avoided, moderate ones may need monitoring or a dose adjustment, and minor ones are usually low-risk. This page shows the documented mechanism and guidance. Label-documented interactions are not a complete safety review, so always confirm your own medications with a pharmacist or doctor. Educational information, not medical advice.
How They Interact
Tranylcypromine blocks the enzyme that normally processes phenylephrine, leading to an extreme and unsafe increase in blood pressure.
What To Do
Do not use these medicines together. Always check with your pharmacist before taking any over-the-counter cold or allergy medicines while on tranylcypromine.
FDA Label Information
Excessive reduction of blood glucose (additive effect) [See Warnings and Precautions (5.14)] ; CNS depressant agents (including opioids, alcohol, sedatives, hypnotics) Use with caution Increased CNS depression Dietary supplements containing sympathomimetics Contraindicated Antidepressants including but not limited to: • Other MAOIs (e.g., linezolid, intravenous methylene blue, selective MAOIs) • Selective serotonin reuptake inhibitors (SSRIs) and serotonin and norepinephrine reuptake inhibitors (SNRIs) • Tricyclic antidepressants • Amoxapine, bupropion, maprotiline, nefazodone, trazodone,...
Tranylcypromine Also Interacts With
- Bupropion major
- Linezolid major
- Vilazodone major
- Epinephrine major
- Norepinephrine major
Frequently Asked Questions
Can I take Phenylephrine and Tranylcypromine together?
This is a major interaction. Do not use these medicines together. Always check with your pharmacist before taking any over-the-counter cold or allergy medicines while on tranylcypromine.
How serious is the interaction between Phenylephrine and Tranylcypromine?
This interaction is classified as "major" severity by the FDA. Major interactions may be life-threatening or cause serious side effects.
Why do Phenylephrine and Tranylcypromine interact?
Tranylcypromine blocks the enzyme that normally processes phenylephrine, leading to an extreme and unsafe increase in blood pressure.
Understanding the Phenylephrine and Tranylcypromine Interaction
FDA-approved prescribing information for these two drugs flags their combination as a major-severity interaction. Phenylephrine belongs to the Alpha-1 Agonist class and Tranylcypromine belongs to the Monoamine Oxidase Inhibitor (MAOI) class - two categories that can collide when co-prescribed. The mechanism described in FDA labeling is: Tranylcypromine blocks the enzyme that normally processes phenylephrine, leading to an extreme and unsafe increase in blood pressure. Severity tiers matter: major flags generally advise avoidance, moderate flags often require monitoring or dose adjustment, and minor flags may only call for awareness.
Context around a specific patient determines real-world impact. Phenylephrine has 2 total documented interactions on file in this dataset, and Tranylcypromine has 42. Each additional medication compounds the interaction surface, which is why pharmacists run full-profile checks rather than evaluating one pair at a time. FDA-derived guidance for this pair is: Do not use these medicines together. Timing of doses, renal and hepatic function, age, and other concurrent prescriptions all shape whether a labeled interaction matters clinically.
An interaction flag is not a verdict. A large share of labeled interactions are managed routinely in clinical practice, the fix may be as simple as spacing doses or adding a monitoring test. Others require the prescriber to choose a different medication entirely. This page surfaces FDA-sourced labeling and openFDA data for educational purposes only; it is not medical advice and cannot account for your full clinical picture. Never start, stop, or adjust either Phenylephrine or Tranylcypromine based on a web page, speak with your prescriber or pharmacist before making any change.
Sources: FDA Drug Labels (SPL) via openFDA (2026). This is for informational purposes only and is not medical advice. Always consult your healthcare provider about drug interactions.
Read our methodology - how this data is sourced, computed, and verified.