Drug & supplement interaction

Isopropylnorsynephrine + Phendimetrazine

Phendimetrazine brand names: Plegine, Metra, Weightrol.

No Known Interaction
Medically reviewed by · Updated July 2026 · Pair last verified Sep 27, 2026
The bottom line No known interaction

We found no known interaction between Isopropylnorsynephrine and Phendimetrazine in our sources. Absence of a documented interaction is not the same as proven safety, and does not guarantee one does not exist. Do not start, stop, or change a medication or supplement based on this page; confirm with your pharmacist or doctor first. Additionally, although there is no interaction, the two are separately associated with some of the same side effects, which would make a new symptom harder to attribute to one or the other.

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Interaction report

Isopropylnorsynephrine and Phendimetrazine

We checked these two against our interaction database. Here is what we found.

No Known Interaction Found

We did not find a documented interaction between Phendimetrazine and Isopropylnorsynephrine in our sources. This does not guarantee that the combination is completely free of risk — there is often limited research on supplements and herbal products, especially around drug interactions.

If you decide to take both, the practical routine is simple: add one new thing at a time and note the date you started it. If the combination is going to disagree with you, it usually shows in the first days to a couple of weeks — and a start date turns “I’ve been feeling off” into something a pharmacist can actually work with. Do not stop a prescribed medicine on your own.

Always talk with your pharmacist or doctor before making changes to your medications or supplements, particularly if you take several medications or have an ongoing health condition.

Isopropylnorsynephrine safety at a glance

Isopropylnorsyneph... overall Use caution It is a poorly studied synthetic stimulant with unknown long-term safety in humans.
Pregnancy Possibly Unsafe When used orally. Isopropylnorsynephrine has been associated with vomiting, hypertension, blurred vision, palpitations, and respiratory distress. When used in c... Read the full pregnancy detail
Breastfeeding Possibly Unsafe When used orally. Isopropylnorsynephrine has been associated with vomiting, hypertension, blurred vision, palpitations, and respiratory distress. When used in c... Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center) — the full detail is in the Special populations card below. Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Still wondering about combining Phendimetrazine and Isopropylnorsynephrine? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Phendimetrazine

Interactions in our licensed database are recorded against drug classes, not just single drug names. Phendimetrazine is filed under a single classification — oral drugs. Isopropylnorsynephrine has documented interactions with 2 drug classes — the most serious being antihypertensive drugs (moderate) and stimulant drugs (moderate) — and none of Phendimetrazine’s classifications are among them.

Classification data comes from our licensed Natural Medicines dataset. A medication can belong to classes beyond those recorded there, so this describes how the check was run — it is not a safety guarantee.

Keep it in perspective

Isopropylnorsynephrine Does Interact With Other Medications

Isopropylnorsynephrine has 344 moderate known drug interactions in our database — Phendimetrazine isn’t one of them. If you take anything else, check it against the full list below.

Moderate 344 No known interaction 2,486 (incl. Phendimetrazine)
Taking anything else?

Check Another of Your Medications Against Isopropylnorsynephrine

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

What to actually watch for

No Interaction Found — But Data Suggests Isopropylnorsynephrine and Phendimetrazine May Share Several of the Same Side Effects

This is not an interaction. Neither one changes how your body handles the other, and nothing here says they react together. What our sources do show is that each has separately been linked to the effects below — so taking both can make those effects more likely to turn up, and harder to pin on one or the other if they do. One of them is worth acting on rather than waiting out — marked below.

  • Raised blood pressure Worth acting on Additional detail

    Isopropylnorsynephrine

    “Orally and parenterally, isopropylnorsynephrine is generally regarded as unsafe.

    Serious Adverse Effects (Rare):

    Orally: Hypertension, palpitations, respiratory distress, and vomiting. Stroke and cardiac arrest have been reported when used with other stimulants or intensive exercise.”

    Isopropylnorsynephrine · Natural Medicines adverse-effect record, reported in acute respiratory distress syndrome (ards).

    “Orally, isopropylnorsynephrine has been associated with hypertension and palpitations. When used in combination with stimulants or intensive exercise, isopropylnorsynephrine has been associated with adverse cardiovascular events such as stroke and cardiac arrest.”

    Isopropylnorsynephrine · Natural Medicines adverse-effect record, reported in cardiac arrest.

    2 sources cited
    1. 21079. Venhuis B, Keizers P, van Riel A, de Kaste D. A cocktail of synthetic stimulants found in a dietary supplement associated with serious adverse events. Drug Test Anal. 2014 Jun;6(6):578-81. doi: 10.1002/dta.1664. Epub 2014 May 6. PubMed
    2. 104949. Cohen PA, Travis JC, Vanhee C, Ohana D, Venhuis BJ. Nine prohibited stimulants found in sports and weight loss supplements: deterenol, phenpromethamine (Vonedrine), oxilofrine, octodrine, beta-methylphenylethylamine (BMPEA), 1,3-dimethylamylamine (1,3-DMA

    Phendimetrazine

    Listed in the ADVERSE REACTIONS section of the FDA label for Phendimetrazine. Read the label on DailyMed ›

  • A fast or pounding heartbeat Additional detail

    Isopropylnorsynephrine

    Recorded for Isopropylnorsynephrine in the same Natural Medicines adverse-effect record shown under Raised blood pressure above.

    Phendimetrazine

    Listed in the ADVERSE REACTIONS section of the FDA label for Phendimetrazine. Read the label on DailyMed ›

Reported for Isopropylnorsynephrine but not commonly for Phendimetrazine: shortness of breath and vomiting.

Effects for Phendimetrazine come from the ADVERSE REACTIONS section of its FDA label; effects for Isopropylnorsynephrine come from the Natural Medicines adverse-effect record, quoted above. Wording is matched across sources by our own clinical vocabulary, so treat this as a prompt to pay attention, not a diagnosis.

Special populations

Isopropylnorsynephrine in Pregnancy & Breastfeeding

Pregnancy And Lactation Possibly Unsafe

When used orally. Isopropylnorsynephrine has been associated with vomiting, hypertension, blurred vision, palpitations, and respiratory distress. When used in combination with stimulants or intensive exercise, isopropylnorsynephrine has been associated with adverse cardiovascular events such as stroke and cardiac arrest. Avoid using.

DISCLAIMER: This tool is intended for informational purposes only, and should not be interpreted as specific medical advice. Patients should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.© 2026 Therapeutic Research Center

Overlapping uses

What Phendimetrazine Is Prescribed For, and What Isopropylnorsynephrine Has Been Studied For

These two come up together because they touch the same health topic — not because they do the same job. Phendimetrazine is a prescription medicine with approved uses on its FDA label. Isopropylnorsynephrine is a supplement: what follows is what researchers have looked at it for, and how strong that evidence is.

Phendimetrazine is prescribed for: Phendimetrazine is used short-term — typically a few weeks — to help manage obesity in adults who have a body mass index (BMI) of 30 or higher, or 27 or higher when other risk factors like high blood pressure, diabetes, or high cholesterol are present, and who have not lost enough weight through diet and exercise alone. Phendimetrazine Tartrate extended-release capsules are specifically indicated for adults meeting those BMI criteria, including those with certain risk factors. Phendimetrazine Tartrate tablets are indicated for adults with a BMI of 30 or higher. Both forms are approved for use as a single medication only — not in combination with other weight-loss drugs or stimulants.

Isopropylnorsynephrine has been studied for:

  • Obesity studied, not established Isopropylnorsynephrine has been studied for this. Natural Medicines rates the evidence: Insufficient Reliable Evidence To Rate Read what the research shows

    Isopropylnorsynephrine for obesity

    Although there is interest in using oral isopropylnorsynephrine for weight loss, there is insufficient reliable information about the clinical effects of isopropylnorsynephrine for this purpose.

Effectiveness ratings and the research summaries above are the verbatim record from the Natural Medicines database, which grades evidence from “Effective” down to “Insufficient Reliable Evidence To Rate”. A rating below the top of that scale means researchers have looked at it — not that it works, and never that it can stand in for a prescribed medicine. Do not stop or replace Phendimetrazine on your own; if you are taking Isopropylnorsynephrine for the same health topic, tell your prescriber, especially if the medicine is being adjusted to a target.

Everything else you take

See Every Supplement That Interacts With Phendimetrazine

This page covers Isopropylnorsynephrine only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Phendimetrazine page lists 17 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Coffee Charcoal (moderate), European Mandrake (moderate), Glucomannan (moderate) and Guar Gum (moderate).

By severity: 1 major · 7 moderate · 9 minor.

From our pharmacist’s overview on the Phendimetrazine page

“Of the 17 supplements on file for phendimetrazine, an appetite-suppressant stimulant prescribed short term for weight loss, activated charcoal is the one that demands real caution. Charcoal binds medications in the gut and can sharply cut how much of a drug your body absorbs, leaving you with less appetite control than your prescriptio…”

Reviewed by 2 · Jul 18, 2026

Open the Phendimetrazine interaction page

One more smart check

Taking Isopropylnorsynephrine as Part of a Dietary Supplement Product? Check It for Interactions

We hold 48 real supplement products containing Isopropylnorsynephrine, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Isopropylnorsynephrine. Even though Isopropylnorsynephrine itself has no known interaction with Phendimetrazine, another ingredient on your label might. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Isopropylnorsynephrine and Phendimetrazine 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 Isopropylnorsynephrine
Top half

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

29 days ago today
Medication Phendimetrazine
Steady interest

#2,271 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.

Where does our data come from?
  • Source: the Natural Medicines (TRC Healthcare) clinical database — the evidence-graded professional reference for herb & supplement interactions.
  • Citation library: 103,510 references behind our interaction content, 65,311 of them resolved to verified PubMed/DOI sources. See every Isopropylnorsynephrine reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 27, 2026. The Isopropylnorsynephrine and Phendimetrazine records this page draws on were last updated July 10, 2026.
  • What “no known interaction” means: no documented interaction in the sources above — not a guarantee of safety. Supplements are studied far less than prescription drugs, so we say exactly what the evidence supports, and nothing more.
Data structure & sourcing designed and verified by .
Supplement

About Isopropylnorsynephrine

What is Isopropylnorsynephrine?

  • Weight loss and fat burning
  • Pre-workout energy and stimulation
  • Topical fat reduction (creams and gels)
  • Appetite suppression
  • Athletic performance

Isopropylnorsynephrine is a synthetic stimulant chemically related to synephrine, marketed mainly in weight-loss and pre-workout supplements. It has very little human safety or effectiveness research, and as a stimulant it may raise heart rate and blood pressure, so caution is strongly advised. Talk with a pharmacist or doctor before using any product that contains it.

Synthetic compound (not a plant part) · Capsules, tablets, powders, and topical gels or creams (often in fat-loss and pre-workout products)

An interaction check asks whether these two react with each other — it does not ask whether Isopropylnorsynephrine is a good idea for someone in your situation. Here is what our Isopropylnorsynephrine record says about it on its own.

Isopropylnorsynephrine: dosing

There is no established or proven safe dose for isopropylnorsynephrine. No official health authority has set a recommended amount, and studies do not provide reliable dosing guidance.If a product contains it, follow the label instructions and do not exceed them.

From our Isopropylnorsynephrine monograph — the full record covers uses, side effects and every documented interaction.

Read the full Isopropylnorsynephrine monograph & all interactions
Medication

About Phendimetrazine

What Is Phendimetrazine Used For?

Brand names: Plegine, Metra, Weightrol

Phendimetrazine is used short-term — typically a few weeks — to help manage obesity in adults who have a body mass index (BMI) of 30 or higher, or 27 or higher when other risk factors like high blood pressure, diabetes, or high cholesterol are present, and who have not lost enough weight through diet and exercise alone.

Phendimetrazine Tartrate extended-release capsules are specifically indicated for adults meeting those BMI criteria, including those with certain risk factors. Phendimetrazine Tartrate tablets are indicated for adults with a BMI of 30 or higher. Both forms are approved for use as a single medication only — not in combination with other weight-loss drugs or stimulants.

See full Phendimetrazine drug information
Keep checking

Other Drugs & Isopropylnorsynephrine

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

0Major
344Moderate
0Minor
2,485No known interaction
344 Moderate 2,485 No interaction
Moderate

344 interactions

Showing 60 of 344 moderate interactions — see all 344 on the Isopropylnorsynephrine page.

No interaction 2,485 drugs checked — show the list

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

Showing the 60 most looked-up of 2,485 medications checked with no known interaction — see the full Isopropylnorsynephrine list.

See the full Isopropylnorsynephrine interactions page
See every supplement checked against Phendimetrazine, ranked by severity
Evidence & sources

Isopropylnorsynephrine References

The 3 references that drive our Isopropylnorsynephrine monograph and interaction data, from the evidence-graded Natural Medicines (TRC Healthcare) database. Citations with a link open the study on PubMed or the publisher’s site.

  1. Venhuis B, Keizers P, van Riel A, de Kaste D. A cocktail of synthetic stimulants found in a dietary supplement associated with serious adverse events. Drug Test Anal. 2014 Jun;6(6):578-81. doi: 10.1002/dta.1664. Epub 2014 May 6. PubMed
  2. Cohen PA, Travis JC, Vanhee C, Ohana D, Venhuis BJ. Nine prohibited stimulants found in sports and weight loss supplements: deterenol, phenpromethamine (Vonedrine), oxilofrine, octodrine, beta-methylphenylethylamine (BMPEA), 1,3-dimethylamylamine (1,3-DMA
  3. Anderson WG. The sympathomimetic activity of N-isopropyloctopamine in vitro. J Pharmacol Exp Ther 1983;225(3):553-8. DOI

Medication overviews come from MedlinePlus (NIH); supplement label data from the NIH Dietary Supplement Label Database. Content is written and reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

Pharmacist Counseling Corner

Taking Isopropylnorsynephrine and Phendimetrazine Together: Common Questions

Is it safe to take Isopropylnorsynephrine with Phendimetrazine?
We do not list a known interaction between Isopropylnorsynephrine and Phendimetrazine. That does not guarantee the combination is risk-free, so confirm with your pharmacist or doctor — especially if you take other medications or have a health condition.
Do Isopropylnorsynephrine and Phendimetrazine have any of the same side effects?
Yes — our sources link each of them separately to 2 of the same effects. That is not an interaction: neither changes how your body handles the other. It does mean that if one of those effects turns up, it can be harder to tell which one is behind it. They are listed on this page with the source behind each.
Are Isopropylnorsynephrine and Phendimetrazine used for the same thing?
They overlap in purpose, which usually means the real question is whether you need both rather than whether they are safe together. This page lists the shared uses and how strong the evidence is for Isopropylnorsynephrine in each. That is a conversation for your prescriber, especially if Phendimetrazine is being adjusted to a target.
How was the Isopropylnorsynephrine and Phendimetrazine combination checked?
Interactions in our licensed database are recorded against drug classes. Phendimetrazine is filed under 1 classification, and Isopropylnorsynephrine has documented interactions with 2 drug classes — none of Phendimetrazine's classifications are among them. A medication can belong to classes beyond those recorded in our dataset, so this describes how the check was run rather than guaranteeing safety.
Does Isopropylnorsynephrine interact with any other medications?
Yes. Isopropylnorsynephrine has 344 documented drug interactions in our database — Phendimetrazine is simply not one of them. If you take anything else, it is worth checking each one; they are all listed on this page.
Does Phendimetrazine interact with any supplements?
Yes. Phendimetrazine has documented interactions with 17 supplements in our database — Isopropylnorsynephrine is not one of them. The Phendimetrazine interaction page linked on this page lists every one, ranked by severity.

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

Where next

Keep Exploring

Isopropylnorsynephrine monograph Uses, safety profile, and every drug interaction in one place Phendimetrazine drug information The full plain-English guide to this medication Phendimetrazine supplement interactions Every supplement checked against Phendimetrazine, 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 References The 3 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Phendimetrazine and Isopropylnorsynephrine?

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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.