Drug & supplement interaction

1,3-dmba + Acetaminophen, Dextromethorphan, Phenylpropanolamine, Pyrilamine

Acetaminophen, Dextromethorphan, Phenylpropanolamine, Pyrilamine brand name: Theracaps.

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

Acetaminophen, Dextromethorphan, Phenylpropanolamine, Pyrilamine falls into 2 drug categories that 1,3-dmba can interact with; the most serious is rated moderate. Theoretically, combining 1,3-DMBA with other stimulant drugs might increase the risk of cardiovascular toxicity.

Read the full interaction report
SeverityModerate
LikelihoodPossible
Interactions2
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

1,3-dmba and Acetaminophen, Dextromethorphan, Phenylpropanolamine, Pyrilamine

These two interact in 2 distinct ways. Each one is explained separately below.

Why Are There 2 Interactions?

1,3-dmba interacts with whole categories of medication. Acetaminophen, Dextromethorphan, Phenylpropanolamine, Pyrilamine falls into 2 of those categories, so it can interact with 1,3-dmba in 2 different ways. We’ve listed each one below — your overall risk is driven by the most serious of them (Moderate).

Moderate

STIMULANT DRUGS

1 of 2

Why this applies to Acetaminophen, Dextromethorphan, Phenylpropanolamine, Pyrilamine

Acetaminophen, Dextromethorphan, Phenylpropanolamine, Pyrilamine 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

The product you asked about (Theracaps) is a cold and cough combo, and the piece that matters here is the phenylpropanolamine. That ingredient is a decongestant that already tightens blood vessels and can nudge your blood pressure and heart rate upward. 1,3-DMBA is a powerful stimulant, so stacking the two could push those effects higher than either alone, raising the chance of a pounding heart, jitteriness, headache, or a spike in blood pressure.

To be fair, this concern is theoretical and comes mostly from animal data, not solid human studies. Still, 1,3-DMBA is an unsafe, FDA-flagged ingredient I'd steer clear of regardless. Please check with your pharmacist or doctor before mixing these.

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.
Minor

CYTOCHROME P450 2D6 (CYP2D6) SUBSTRATES

2 of 2

Acetaminophen, Dextromethorphan, Phenylpropanolamine, Pyrilamine also falls under CYTOCHROME P450 2D6 (CYP2D6) SUBSTRATES.

Theoretically, 1,3-DMBA might modestly increase the levels of CYP2D6 substrates.
In vitro research shows that 1,3-DMBA weakly inhibits CYP2D6 enzymes.
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

This combination cold-and-cough product contains dextromethorphan, which your body clears using a liver enzyme called CYP2D6. Lab studies suggest 1,3-DMBA may weakly block that enzyme. If it does, dextromethorphan could clear a little slower and build up slightly, which might bump up side effects like dizziness, drowsiness, or feeling foggy or restless.

Honestly, though, the bigger concern here isn't the enzyme. 1,3-DMBA is a banned, unsafe stimulant that can raise your heart rate and blood pressure, and this product already has phenylpropanolamine, another decongestant stimulant. Stacking them could strain your heart. This enzyme effect is only theoretical (test-tube data), but please don't use any product with 1,3-DMBA. Check with your pharmacist or doctor.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Liu Y, Santillo MF. Cytochrome P450 2D6 and 3A4 enzyme inhibition by amine stimulants in dietary supplements. Drug Test Anal. 2016;8(3-4):307-10. 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

1,3-dmba Also Interacts With Other Medications

1,3-dmba has 171 moderate, 149 minor known drug interactions in our database — the Acetaminophen, Dextromethorphan, Phenylpropanolamine, Pyrilamine one above is among them. If you take anything else, check it against the full list below.

Moderate 171 Minor 149 No known interaction 2,510 (incl. Acetaminophen, Dextromethorphan, Phenylpropanolamine, Pyrilamine)
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.

Everything else you take

See Every Supplement That Interacts With Acetaminophen, Dextromethorphan, Phenylpropanolamine, Pyrilamine

This page covers 1,3-dmba only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Acetaminophen, Dextromethorphan, Phenylpropanolamine, Pyrilamine page lists 282 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Asarabacca (major), Beer (major), Ephedra (major) and Grapefruit (major).

By severity: 14 major · 223 moderate · 45 minor.

From our pharmacist’s overview on the Acetaminophen, Dextromethorphan, Phenylpropanolamine, Pyrilamine page

“Of everything on this page, ephedra worries me most for anyone using Theracaps (acetaminophen, dextromethorphan, phenylpropanolamine, and pyrilamine), because the decongestant in this cold formula is itself a stimulant. Adding ephedra or any of the 44 stimulant entries can push blood pressure and heart rate to unsafe levels.”

Reviewed by 2 · Jul 18, 2026

Open the Acetaminophen, Dextromethorphan, Phenylpropanolamine, Pyrilamine interaction page

How much people look this up

Where 1,3-dmba and Acetaminophen, Dextromethorphan, Phenylpropanolamine, Pyrilamine 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

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

29 days ago today
Medication Acetaminophen, Dextromethorphan, Phenylpropanolamine, Pyrilamine
Top 10%

#165 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
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 Acetaminophen, Dextromethorphan, Phenylpropanolamine, Pyrilamine, 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 Acetaminophen, Dextromethorphan, Phenylpropanolamine, Pyrilamine supplement interactions › Every supplement checked against Acetaminophen, Dextromethorphan, Phenylpropanolamine, Pyrilamine, 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 1,3-dmba and Acetaminophen, Dextromethorphan, Phenylpropanolamine, Pyrilamine Together: Common Questions

Can you take 1,3-dmba with Acetaminophen, Dextromethorphan, Phenylpropanolamine, Pyrilamine?
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.
Why are there 2 interactions listed for 1,3-dmba and Acetaminophen, Dextromethorphan, Phenylpropanolamine, Pyrilamine?
Acetaminophen, Dextromethorphan, Phenylpropanolamine, Pyrilamine belongs to more than one drug category, and 1,3-dmba interacts with each of those categories a little differently. We list every one so nothing is missed — your overall risk is driven by the most serious of them.
How serious is the 1,3-dmba and Acetaminophen, Dextromethorphan, Phenylpropanolamine, Pyrilamine 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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