Drug & supplement interaction

N-methyltyramine + Phenylephrine

Phenylephrine brand names: Gilchew, AH Chew D, Gilchew IR, Sudafed PE, Biorphen.

Minor Interaction
Medically reviewed by · Updated September 2026
The bottom line Minor

N-methyltyramine has a minor interaction with Phenylephrine. N-methyltyramine is thought to have stimulant effects.

Read the full interaction report
SeverityMinor
LikelihoodPossible
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

N-methyltyramine and Phenylephrine

Here is the interaction we found between these two, with the evidence behind it.

Minor

STIMULANT DRUGS

Why this applies to Phenylephrine

Phenylephrine falls under STIMULANT DRUGS — the group N-methyltyramine interacts with.

N-methyltyramine is thought to have stimulant effects. However, this has not been shown in humans and laboratory research does not support the proposed stimulant effects of N-methyltyramine. Theoretically, taking N-methyltyramine with other stimulant drugs might increase the risk of hypertension and adverse cardiovascular effects. Until more is known, avoid taking N-methyltyramine with stimulant drugs.
Some stimulant drugs include amphetamine, caffeine, diethylpropion (Tenuate), methylphenidate, phentermine (Ionamin), pseudoephedrine (Sudafed, others), and many others.
Severity Minor Likelihood Possible Evidence D

Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the simple version. Phenylephrine is a decongestant that works by tightening the blood vessels in your nose, but it can also nudge up your heart rate and blood pressure. N-methyltyramine is thought to act as a mild stimulant too. So in theory, stacking the two could add up and make those stimulant-type effects stronger, things like a faster or pounding heartbeat, jitteriness, or a higher blood pressure reading.

I want to be honest with you, though: this is a theoretical concern. It hasn't actually been shown in people, and some lab work doesn't even back up the stimulant claim. The risk is rated minor. Still, if you have heart issues or high blood pressure, play it safe and check with your pharmacist or doctor before combining them.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Pawar RS, Grundel E. Overview of regulation of dietary supplements in the USA and issues of adulteration with phenethylamines (PEAs). Drug Test Anal 2017;9:500-517. PubMed
  2. Stohs SJ, Hartman MJ. A review of the receptor binding and pharmacological effects of N-methyltyramine. Phytother Res. 2015;29(1):14-6.

What These Ratings Mean

Every interaction above is graded three ways — here’s the key to each label.

Severity how clinically significant the interaction is
Major

Clinically significant. Avoid the combination, or use only under close professional supervision.

Moderate

Usually worth avoiding or managing — may need monitoring, a dose change, or timing apart.

Minor

Generally not serious. Be aware of it and mention it to your pharmacist.

Likelihood how strong the evidence is that the interaction actually happens in people
  • LikelyWell-controlled human studies have demonstrated the likely existence of this interaction.
  • ProbableInteraction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
  • PossibleInteraction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.
  • UnlikelyInteraction has been demonstrated in animal or in lab research but has been shown not to occur in humans.
Evidence the quality of the studies behind the rating (graded A–D)
  • AHigh-quality meta-analysis (quantitative systematic review).
  • BCase-control study.
  • CConsensus.
  • DAnecdotal evidence.

These ratings are for information only. Never start, stop, or otherwise change your therapy before speaking with your provider.

Keep it in perspective

N-methyltyramine Also Interacts With Other Medications

N-methyltyramine has 343 minor known drug interactions in our database — the Phenylephrine one above is one of them. If you take anything else, check it against the full list below.

Minor 343 No known interaction 2,487 (incl. Phenylephrine)
Taking anything else?

Check Another of Your Medications Against N-methyltyramine

Covers the 2,830 medications we’ve checked against N-methyltyramine. Pick one to open its full report.

From our Q&A

Questions About N-methyltyramine or Phenylephrine

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers N-methyltyramine or Phenylephrine, not necessarily both, but if one is close to what you were about to ask it will usually go further than a database entry can:

Not quite your question? Ask our pharmacists directly — it is free, there is no account required, and answers usually come back within 24 hours.

Everything else you take

See Every Supplement That Interacts With Phenylephrine

This page covers N-methyltyramine only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Phenylephrine page lists 81 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Ephedra (major), Lithium (major), Peyote (major) and Rauvolfia Vomitoria (major).

By severity: 6 major · 60 moderate · 15 minor.

From our pharmacist’s overview on the Phenylephrine page

“If you take phenylephrine (Sudafed PE, Biorphen) for congestion, treat this list as one that needs real attention, since six of its 81 entries carry a major rating. Phenylephrine tightens blood vessels to clear your nose, and more than half of the interactions here come from stimulant ingredients, ephedra above all, that can push blood…”

Reviewed by 2 · Jul 18, 2026

Open the Phenylephrine interaction page

One more smart check

Taking N-methyltyramine as Part of a Dietary Supplement Product? Check It for Interactions

We hold 213 real supplement products containing N-methyltyramine, each one broken down to its full ingredient list — and combination products often carry several ingredients besides N-methyltyramine. Your product may carry other ingredients that interact with Phenylephrine too, on top of N-methyltyramine — and those would not show on this page. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where N-methyltyramine and Phenylephrine Sit Against Everything Else

Out of every supplement and medication people look up on HelloPharmacist, here is where these two land this week — and which way each has been moving.

Supplement N-methyltyramine
Top half

#482 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Phenylephrine
Top 25%

#639 of 2,830 medications looked up here in the last 7 days

29 days ago today

Position among everything looked up on this site, not a measure of how commonly either one is used or how important it is. A supplement can climb this list because of a news story. It counts every request to the page, automated ones included, and nothing here identifies anyone.

Supplement

About N-methyltyramine

What is N-methyltyramine?

  • Weight loss and fat burning
  • Energy and pre-workout supplements
  • Sports performance
  • Appetite control

N-methyltyramine is a natural compound related to tyramine that is found in bitter orange, barley, and other plants, and it is often added to weight-loss and pre-workout supplements. Solid human research on its safety and effectiveness is very limited, and because it may stimulate the body like other amines, people with heart problems or high blood pressure should be especially careful. Talk to a pharmacist or doctor before using any product that contains it.

Read the full N-methyltyramine monograph & all interactions
Medication

About Phenylephrine

What Is Phenylephrine Used For?

Brand names: Gilchew, AH Chew D, Gilchew IR, Sudafed PE, Biorphen

Phenylephrine is used in a number of different forms for different purposes. Intravenous (IV) phenylephrine — including products like Biorphen and Immphentiv — is given in hospital settings to raise blood pressure in adults when it drops dangerously low due to blood vessel widening (vasodilation), such as during anesthesia. Phenylephrine Hydrochloride Injection 10 mg/mL is also approved for use in septic shock (a life-threatening infection that causes a severe drop in blood pressure).

Nasal spray and drop products (such as Neo-Synephrine and Equate Nasal) temporarily relieve nasal congestion from colds, hay fever, or upper respiratory allergies. Ophthalmic (eye drop) solutions dilate the pupil for eye exams. Rectal suppository products (such as Preparation H and ReVIVOL-XR) help relieve itching, burning, and discomfort associated with hemorrhoids.

See full Phenylephrine drug information
Keep checking

Other Drugs & N-methyltyramine

Browse every other medication we’ve checked against N-methyltyramine — both the ones with a known interaction and the ones without. Select any drug for the full detail.

0Major
0Moderate
343Minor
2,486No known interaction
343 Minor 2,486 No interaction
Minor

343 interactions

Showing 60 of 343 minor interactions — see all 343 on the N-methyltyramine page.

No interaction 2,486 drugs checked — show the list

We also checked N-methyltyramine against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 2,486 medications checked with no known interaction — see the full N-methyltyramine list.

See the full N-methyltyramine interactions page
See every supplement checked against Phenylephrine, ranked by severity
Sources

Sources & How We Checked

Interaction details are evidence-graded and sourced from the Natural Medicines database. The medication overview comes from MedlinePlus.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

Parts of this content are provided by the Therapeutic Research Center, LLC.

DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

© 2021 Therapeutic Research Center, LLC

Keep exploring
N-methyltyramine monograph › Uses, safety, and every drug interaction in one place Phenylephrine supplement interactions › Every supplement checked against Phenylephrine, ranked by severity Phenylephrine drug information › The full plain-English guide to this medication Supplement interaction checker › Check any supplement or product against your medications Browse medications A–Z › Every drug we've checked against herbs & supplements Ask a pharmacist › Free, personal answer from our licensed team
Pharmacist Counseling Corner

Taking N-methyltyramine and Phenylephrine Together: Common Questions

Can you take N-methyltyramine with Phenylephrine?
There is only a minor interaction, which is usually not serious. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the N-methyltyramine and Phenylephrine interaction?
We rate it Minor. This interaction is generally not clinically significant, but it remains worth noting and discussing with your pharmacist.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

Still Have a Question About Phenylephrine and N-methyltyramine?

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This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.