Drug & supplement interaction

1,4-dmaa + Guaifenesin, Phenylephrine

Guaifenesin, Phenylephrine brand names: Amidal, Endal, Numonyl Sr, Liquibid-D, Deconsal Sprinkle, and others.

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

1,4-dmaa has a moderate interaction with Guaifenesin, Phenylephrine. 1,4-DMAA is thought to have stimulant and vasoconstrictive effects, which have been demonstrated in animal studies.

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

1,4-dmaa and Guaifenesin, Phenylephrine

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

Moderate

STIMULANT DRUGS

Why this applies to Guaifenesin, Phenylephrine

Guaifenesin, Phenylephrine falls under STIMULANT DRUGS — the group 1,4-dmaa interacts with.

1,4-DMAA is thought to have stimulant and vasoconstrictive effects, which have been demonstrated in animal studies. Theoretically, taking 1,4-DMAA with stimulant drugs might increase the risk of adverse cardiovascular effects. Some stimulant drugs include amphetamine, caffeine, diethylpropion (Tenuate), methylphenidate, phentermine (Ionamin), pseudoephedrine (Sudafed, others), and many others.
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 about pairing 1,4-DMAA with a product that contains phenylephrine (the guaifenesin part just loosens mucus and isn't the concern here). Phenylephrine is a decongestant that works by tightening blood vessels, which can nudge your blood pressure up. 1,4-DMAA acts like a stimulant and does much the same thing. Stack them together and you may be doubling up on that effect.

On paper, that could mean a faster or pounding heartbeat, a real spike in blood pressure, headache, jitteriness, or chest discomfort. To be honest, most of this is theoretical, based on how these ingredients behave rather than solid human studies. But since the FDA considers 1,4-DMAA unsafe to begin with, I'd steer clear of it and check with your pharmacist before combining anything like this.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Cohen PA, Travis JC, Keizers PHJ, Deuster P, Venhuis BJ. Four experimental stimulants found in sports and weight loss supplements: 2-amino-6-methylheptane (octodrine), 1,4-dimethylamylamine (1,4-DMAA), 1,3-dimethylamylamine (1,3-DMAA) and 1,3-dimethylbuty

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

1,4-dmaa Also Interacts With Other Medications

1,4-dmaa has 171 moderate known drug interactions in our database — the Guaifenesin, Phenylephrine one above is one of them. If you take anything else, check it against the full list below.

Moderate 171 No known interaction 2,659 (incl. Guaifenesin, Phenylephrine)
Taking anything else?

Check Another of Your Medications Against 1,4-dmaa

Covers the 2,830 medications we’ve checked against 1,4-dmaa. Pick one to open its full report.

Everything else you take

See Every Supplement That Interacts With Guaifenesin, Phenylephrine

This page covers 1,4-dmaa only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Guaifenesin, Phenylephrine page lists 62 supplements it has a documented interaction with, worst first, each one explained.

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

By severity: 5 major · 44 moderate · 13 minor.

From our pharmacist’s overview on the Guaifenesin, Phenylephrine page

“Phenylephrine, the decongestant half of guaifenesin and phenylephrine (Endal, Liquibid-D, Deconsal), tightens blood vessels and raises blood pressure and heart rate, so this list of 62 interacting supplements calls for genuine care. Forty-four of them can pile extra stimulation on top of the drug's own effect, and five rate major, most…”

Reviewed by 2 · Jul 18, 2026

Open the Guaifenesin, Phenylephrine interaction page

How much people look this up

Where 1,4-dmaa and Guaifenesin, 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 1,4-dmaa
Steady interest

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

29 days ago today
Medication Guaifenesin, Phenylephrine
Steady interest

#2,459 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 1,4-dmaa

What is 1,4-dmaa?

  • Energy and stimulation
  • Weight loss
  • Athletic performance
  • Focus and concentration

1,4-DMAA is a synthetic stimulant that the U.S. FDA has determined is not a legal dietary ingredient and considers unsafe in supplements. It has been linked to serious heart and blood pressure problems, and we recommend avoiding it entirely.

Read the full 1,4-dmaa monograph & all interactions
Keep checking

Other Drugs & 1,4-dmaa

Browse every other medication we’ve checked against 1,4-dmaa — both the ones with a known interaction and the ones without. Select any drug for the full detail.

0Major
171Moderate
0Minor
2,658No known interaction
171 Moderate 2,658 No interaction
Moderate

171 interactions

Showing 60 of 171 moderate interactions — see all 171 on the 1,4-dmaa page.

No interaction 2,658 drugs checked — show the list

We also checked 1,4-dmaa against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 2,658 medications checked with no known interaction — see the full 1,4-dmaa list.

See the full 1,4-dmaa interactions page
See every supplement checked against Guaifenesin, 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
1,4-dmaa monograph › Uses, safety, and every drug interaction in one place Guaifenesin, Phenylephrine supplement interactions › Every supplement checked against Guaifenesin, Phenylephrine, ranked by severity 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 1,4-dmaa and Guaifenesin, Phenylephrine Together: Common Questions

Can you take 1,4-dmaa with Guaifenesin, 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 1,4-dmaa and Guaifenesin, 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 Guaifenesin, Phenylephrine and 1,4-dmaa?

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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.