Drug & supplement interaction

1,3-dmba + 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

1,3-dmba has a moderate interaction with Phenylephrine. Theoretically, combining 1,3-DMBA with other stimulant drugs might increase the risk of cardiovascular toxicity.

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

1,3-dmba and Phenylephrine

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

Moderate

STIMULANT DRUGS

Why this applies to Phenylephrine

Phenylephrine falls under STIMULANT DRUGS — the group 1,3-dmba interacts with.

Theoretically, combining 1,3-DMBA with other stimulant drugs might increase the risk of cardiovascular toxicity.
Animal research shows that 1,3-DMBA has stimulant effects, such as increasing blood pressure and heart rate.
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 simple version: phenylephrine, the decongestant in products like Sudafed PE, is itself a mild stimulant. It tightens blood vessels in your nose to clear congestion, but that same action can nudge your blood pressure up a bit. 1,3-DMBA is also a stimulant, very similar to the banned ingredient DMAA. So you'd basically be stacking two stimulants on top of each other.

Putting them together could add up to a higher heart rate, raised blood pressure, jitteriness, or palpitations. I'll be honest, this concern comes from animal and lab research, not solid human studies, so it's more theoretical than proven. Still, I'd steer clear of 1,3-DMBA altogether since the FDA considers it unsafe. Please check with your pharmacist or doctor before combining them.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. SWANSON EE, CHEN KK. Comparison of pressor action of alicyclic derivatives of aliphatic amines. J Pharmacol Exp Ther. 1948 Aug;93(4):423-9.

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

1,3-dmba Also Interacts With Other Medications

1,3-dmba has 171 moderate, 149 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.

Moderate 171 Minor 149 No known interaction 2,510 (incl. Phenylephrine)
Taking anything else?

Check Another of Your Medications Against 1,3-dmba

Covers the 2,830 medications we’ve checked against 1,3-dmba. Pick one to open its full report.

From our Q&A

Questions About 1,3-dmba 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 1,3-dmba 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 1,3-dmba 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

How much people look this up

Where 1,3-dmba 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 1,3-dmba
Steady interest

#1,035 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Phenylephrine
Top 25%

#675 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 1,3-dmba

What is 1,3-dmba?

  • Athletic and workout performance
  • Energy and stimulation
  • Weight loss and fat burning
  • Appetite suppression
  • Focus and concentration

1,3-DMBA is a synthetic stimulant chemically similar to the banned stimulant DMAA, and it is not a proven or safe dietary ingredient. The U.S. FDA considers supplements containing it adulterated, and it is banned in sports. Because of serious heart and stroke risks, it is best to avoid products that contain it.

Read the full 1,3-dmba 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 & 1,3-dmba

Browse every other medication we’ve checked against 1,3-dmba — both the ones with a known interaction and the ones without. Select any drug for the full detail.

0Major
171Moderate
149Minor
2,509No known interaction
171 Moderate 149 Minor 2,509 No interaction
Moderate

171 interactions

Showing 60 of 171 moderate interactions — see all 171 on the 1,3-dmba page.

Minor

149 interactions

Showing 60 of 149 minor interactions — see all 149 on the 1,3-dmba page.

No interaction 2,509 drugs checked — show the list

We also checked 1,3-dmba against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 2,509 medications checked with no known interaction — see the full 1,3-dmba list.

See the full 1,3-dmba 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
1,3-dmba 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 1,3-dmba and Phenylephrine Together: Common Questions

Can you take 1,3-dmba 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 1,3-dmba 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

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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.