Drug & supplement interaction

Phenethylamine (pea) + Phenylephrine

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

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

Phenethylamine (pea) has a moderate interaction with Phenylephrine. Theoretically, combining serotonergic drugs with phenethylamine might increase the risk of serotonergic adverse effects.

Read the full interaction report
SeverityModerate
LikelihoodPossible
EvidenceD
What do Severity, Likelihood & Evidence mean?
Know someone taking this? Share
Facebook Post Reddit Email
On this page
Interaction report

Phenethylamine (pea) and Phenylephrine

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

Moderate

SEROTONERGIC DRUGS

Why this applies to Phenylephrine

Phenylephrine falls under SEROTONERGIC DRUGS — the group Phenethylamine (pea) interacts with.

Theoretically, combining serotonergic drugs with phenethylamine might increase the risk of serotonergic adverse effects.
Animal research shows that phenethylamine increases levels of serotonin, norepinephrine, and dopamine. Theoretically, combining serotonergic drugs with phenethylamine might increase the risk of additive serotonergic adverse effects, including serotonin syndrome and cerebral vasoconstrictive disorders. However, low-quality clinical research has used phenethylamine with selegiline, a monoamine oxidase inhibitor (MAOI), with apparent safety.
Severity Moderate 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 thing to keep in mind: both phenylephrine and PEA can nudge your body's adrenaline-type signals in the same direction. Phenylephrine works by tightening blood vessels (that's how it clears a stuffy nose), and PEA may boost messengers like norepinephrine. Stacking them together could, in theory, add up to higher blood pressure, a faster or pounding heartbeat, headache, or jitteriness.

Now, the honest part: this concern comes from animal and lab studies, not solid human research, so it's more of a caution than a proven problem. Still, if you have heart issues or high blood pressure, or you're taking other stimulant-like products, it's worth a quick chat with your pharmacist or doctor before combining them.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Singhal AB, Caviness VS, Begleiter AF, et al. Cerebral vasoconstriction and stroke after use of serotonergic drugs. Neurology 2002;58:130-3. PubMed
  2. Sabelli H, Fink P, Fawcett J, et al. Sustained antidepressant effect of PEA replacement. J Neuropsychiatry Clin Neurosci. 1996;8(2):168-71.
  3. Xie Z, Miller G. Beta-phenylehtylamine alters monoamine transporter function via trace amine-associated receptor 1: implication for modulatory roles of trace amines in brain. J Pharmacol Exp Ther. 2008;325(2):617-28.
  4. Nakamura M, Ishii A, Nakahara D. Characterization of beta-phenyltheylamine-induced monoamine release in rat nucleus accumbens: a microdialysis study. Eur J Pharmacol. 1998;349(2-3):163-9.
  5. Bailey B, Philips S, Boulton A. In vivo release of endogenous dopamine, 5-hydroxytryptamine and some of their metabolites from rat caudate nucleus by phenylethylamine. Neurochem Res. 1987;12(2):173-8. PubMed

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

Phenethylamine (pea) Also Interacts With Other Medications

Phenethylamine (pea) has 186 moderate 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.

Moderate 186 No known interaction 2,644 (incl. Phenylephrine)
Taking anything else?

Check Another of Your Medications Against Phenethylamine (pea)

Covers the 2,830 medications we’ve checked against Phenethylamine (pea). Pick one to open its full report.

From our Q&A

Questions About Phenethylamine (pea) 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 Phenethylamine (pea) 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 Phenethylamine (pea) 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 Phenethylamine (pea) as Part of a Dietary Supplement Product? Check It for Interactions

We hold 208 real supplement products containing Phenethylamine (pea), each one broken down to its full ingredient list — and combination products often carry several ingredients besides Phenethylamine (pea). Your product may carry other ingredients that interact with Phenylephrine too, on top of Phenethylamine (pea) — 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 Phenethylamine (pea) 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 Phenethylamine (pea)
Top half

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

29 days ago today
Medication Phenylephrine
Top 25%

#660 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 Phenethylamine (pea)

What is Phenethylamine (pea)?

Phenethylamine (pea)
  • Mood support
  • Focus and concentration
  • Energy and pre-workout boost
  • Feeling of well-being
  • Athletic performance

Phenethylamine (PEA) is a natural compound made in the body and found in foods like chocolate; supplements are marketed for mood, focus, and energy. Reliable human research on the supplement is very limited, and it may raise blood pressure or heart rate, so people with heart or blood pressure problems should be cautious and check with a pharmacist or doctor first.

Read the full Phenethylamine (pea) 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 & Phenethylamine (pea)

Browse every other medication we’ve checked against Phenethylamine (pea) — both the ones with a known interaction and the ones without. Select any drug for the full detail.

0Major
186Moderate
0Minor
2,643No known interaction
186 Moderate 2,643 No interaction
Moderate

186 interactions

Showing 60 of 186 moderate interactions — see all 186 on the Phenethylamine (pea) page.

No interaction 2,643 drugs checked — show the list

We also checked Phenethylamine (pea) against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 2,643 medications checked with no known interaction — see the full Phenethylamine (pea) list.

See the full Phenethylamine (pea) 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
Phenethylamine (pea) 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 Phenethylamine (pea) and Phenylephrine Together: Common Questions

Can you take Phenethylamine (pea) with Phenylephrine?
There is a moderate interaction, so it may be acceptable with monitoring or timing changes — but check with your pharmacist first. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the Phenethylamine (pea) and Phenylephrine interaction?
We rate it Moderate. This combination may require monitoring, a dose adjustment, or separating the times you take each one. Consult your pharmacist before using them together.

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

Still Have a Question About Phenylephrine and Phenethylamine (pea)?

Our pharmacists answer your medication & supplement questions — free.

Ask a pharmacist

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.