Herb & supplement monograph

Methylsynephrine Drug Interactions, Uses, Safety & More

Medically reviewed by ·Updated July 2026
What is this page for?

First and foremost: how Methylsynephrine interacts with medications. The heart of this page is the interaction list — every drug Methylsynephrine is known to interact with, and how serious each one is.

But these pages have grown well beyond that into a full monograph — what Methylsynephrine is, what people use it for and how strong the evidence is, its safety and side effects, and answers to the questions we’re asked most — written and reviewed by the clinical staff at HelloPharmacist. It’s educational information from our licensed clinical databases, not medical advice, and we don’t sell or endorse products. Our editorial policy

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Methylsynephrine Drug Interactions: The Bottom Line

From the HelloPharmacist Editorial Team · Updated July 2026

Based on the available evidence, the overall risk of a serious Methylsynephrine drug interaction appears modest for most people, though caution makes sense with other medicines that stimulate the heart or raise blood pressure. None of the listed interactions are rated major, and every concern on file is theoretical rather than confirmed in human studies.

Interactions deserving the most attention

The combinations that deserve the most care involve stimulant drugs such as amphetamine, methylphenidate, phentermine, pseudoephedrine, and even caffeine, since methylsynephrine is itself a stimulant and pairing it with these could add to blood pressure and heart-related effects. The other group is beta-adrenergic agonists like albuterol and terbutaline, where large amounts of methylsynephrine might strengthen their effects on the heart. Both concerns are predicted from how the chemical works, not from documented harm in people.

What the rest of the list means

Although the number of medications on the list looks large, nearly all of them fall into just these two broad groups. The interactions are based on methylsynephrine's known stimulant activity rather than on human studies showing actual problems, so many combinations may never cause a noticeable effect. Still, because the concerns center on the heart and blood pressure, they are worth taking seriously rather than ignoring.

Check your medications against Methylsynephrine

Based on HelloPharmacist’s Methylsynephrine interaction data and reviewed under our editorial standards.

Interaction report

Drugs that interact with Methylsynephrine

191 medications have a known interaction with Methylsynephrine, graded by severity. Select any drug for the full evidence-based detail.

2,830 drugs
Acetaminophen, Aspirin, CaffeineExcedrin, Excedrin Extra Strength, Excedrin Migraine› Acetaminophen, Brompheniramine, PhenylpropanolamineDimetapp Cold and Flu› Acetaminophen, Butalbital, CaffeineEsgic, Esgic Plus, Fiogesic, Fioricet, Repan, Tecnal +1 more› Acetaminophen, Butalbital, Caffeine, CodeineEsgic with Codeine, Fioricet w/ Codeine› Acetaminophen, Caffeine, Chlorpheniramine, Hydrocodone, PhenylephrineHycomine Compound› Acetaminophen, Caffeine, CodeineGesic C15, Gesic C30, Gesic C8, Lenoltec 1, Lenoltec 2, Lenoltec 3 +1 more› Acetaminophen, Caffeine, Codeine, SalicylamideCodalan No.1, Codalan No.2, Codalan No.3› Acetaminophen, Caffeine, DihydrocodeineDHC Plus, Panlor DC, Panlor SS› Acetaminophen, Caffeine, IsomethepteneMigralam› Acetaminophen, Caffeine, PyrilamineMidol Max Strength Menstrual› Acetaminophen, Chlorpheniramine, Codeine, PhenylephrineColrex› Acetaminophen, Chlorpheniramine, Dextromethorphan, PhenylpropanolamineMulti Symptom Cold Relief› Acetaminophen, Chlorpheniramine, Dextromethorphan, PseudoephedrineChildren's Tylenol Cold Plus Cough, Tylenol Cold Ex Strength› Acetaminophen, Chlorpheniramine, Guaifenesin, Phenylephrine, SalicylamideRhinogesic GG› Acetaminophen, Chlorpheniramine, PhenylephrineAlka-Seltzer PLUS, Histex SR, Protid› Acetaminophen, Chlorpheniramine, Phenylephrine, SalicylamideRhinogesic, Rhinogesic JR› Acetaminophen, Chlorpheniramine, PhenylpropanolamineAlumadrine, Conex, Sinadrin Max Strength, Sinulin› Acetaminophen, Chlorpheniramine, Phenylpropanolamine, OpiumHista-Derfule› Acetaminophen, Chlorpheniramine, Phenylpropanolamine, PhenyltoloxamineNorel Plus› Acetaminophen, Chlorpheniramine, PseudoephedrineAlka-Seltzer PLUS Liquid Gels, Children's Tylenol Cold, Codimal, Comtrex, Extra Strength Tylenol Allergy Sinus, Lorsin +3 more› Acetaminophen, Dexbrompheniramine, PseudoephedrineSinadrin Plus› Acetaminophen, Dextromethorphan, Doxylamine, PseudoephedrineVicks NyQuil› Acetaminophen, Dextromethorphan, Guaifenesin, PhenylephrineConar-A› Acetaminophen, Dextromethorphan, Guaifenesin, PhenylpropanolamineAnatuss› Acetaminophen, Dextromethorphan, Guaifenesin, PseudoephedrineRobitussin Cold, Severe Cold, Suphedrine Cold/Cough› Acetaminophen, Dextromethorphan, Phenylpropanolamine, PyrilamineTheracaps› Acetaminophen, Dextromethorphan, PseudoephedrineAlka-Seltzer PLUS Flu Liquid Gels, Non Aspirin Cold Caps, Tylenol Cold, Tylenol Flu Daytime Ex Strength, Tylenol Flu Ex Strength› Acetaminophen, Dichloralantipyrine, IsomethepteneAmidrine, Midchlor, Migquin, Migratine› Acetaminophen, Dichloralphenazone, IsomethepteneMidrin› Acetaminophen, Dichlorophenazone, IsometheptaneIsocom›
Read The List Like a Pharmacist

What Severity, Likelihood & Evidence Mean

Severity — How Serious It Can Be

  • Major. Clinically significant; generally best avoided, or used only under direct professional supervision.
  • Moderate. May need monitoring, a dose adjustment, or separating the times you take each one.
  • Minor. Generally not clinically significant, but still worth noting and mentioning to your pharmacist.
  • No known interaction. Checked against our sources with nothing documented — not the same as proven safety.

Likelihood — How Well It’s Documented

  • Likely. Well-controlled human studies have demonstrated the likely existence of this interaction
  • Probable. Interaction 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.
  • Possible. 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
  • Unlikely. Interaction has been demonstrated in animal or in lab research but has been shown not to occur in humans.

Where This Data Comes From

  • Interaction records are evidence-graded and sourced from the Natural Medicines database (TRC Healthcare), the same reference used by pharmacists and hospitals.
  • Each drug listed above links to the full report for that exact Methylsynephrine combination — clinical detail, likelihood, evidence level, and citations.
  • Content is reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.
The big picture

The kinds of drugs Methylsynephrine affects

Every type of medication (drug category) Methylsynephrine is known to interact with. Open any category for the detail — or search your exact drug in the checker above.

All 2 drug categories Methylsynephrine interacts with
Beta-adrenergic AgonistsStimulant Drugs
Beta-Adrenergic Agonists

Methylsynephrine has beta agonist activity. Theoretically, concomitant use of large amounts of methylsynephrine might increase the cardiac inotropic effects of beta-agonists. Beta-adrenergic agonists include albuterol (Ventolin, Proventil), metaproterenol (Alupent), terbutaline (Brethine, Bricanyl), and isoproterenol (Isuprel).

Likelihood Possible Evidence D
Stimulant Drugs

Methylsynephrine has cardiac stimulant effects. Theoretically, taking methylsynephrine with other stimulant drugs might increase the risk of hypertension and adverse cardiovascular effects.
Some stimulant drugs include amphetamine, caffeine, diethylpropion (Tenuate), methylphenidate, phentermine (Ionamin), pseudoephedrine (Sudafed, others), and many others.

Likelihood Possible Evidence D
Monograph

Methylsynephrine: Uses, Safety & Side Effects

Medically reviewed by · Reviewed July 2026 ·
The bottom line

Methylsynephrine (also called oxilofrine) is a synthetic stimulant sometimes added to weight-loss and pre-workout products, but it is not a legal or approved dietary ingredient in the United States. It has been linked to serious heart and blood pressure problems, and there is no good evidence it is safe or effective for these uses, so it is best avoided.

Part used
Synthetic compound (also reported in some Citrus species)
Common forms
Capsules, tablets, powders (mostly in weight-loss and pre-workout supplements)
People commonly use it for
  • Weight loss and fat burning
  • Boosting energy
  • Athletic and workout performance
  • Appetite control

Popular and traditional uses — not proof it works. See “Uses & effectiveness” below for the evidence.

Safety at a glance
OverallBest avoided

It is a stimulant drug not approved as a supplement and has been tied to serious cardiovascular events.

PregnancyInsufficient reliable information

Insufficient reliable information available; avoid using.

Read the full pregnancy detail
BreastfeedingInsufficient reliable information

Insufficient reliable information available; avoid using.

Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center). Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Jump to a section

Overview

Methylsynephrine is a stimulant chemical. It is also known by the drug name oxilofrine (or methylsynephrine/oxyephrine). In some countries it has been used as a prescription medicine to raise low blood pressure, but it is not approved as a medicine or a supplement in the United States.

It is chemically related to synephrine and ephedrine, which are other stimulant compounds. Methylsynephrine is sometimes found in products marketed for weight loss, energy, and pre-workout performance. Regulators, including the U.S. Food and Drug Administration (FDA), have warned that it does not meet the legal definition of a dietary ingredient and should not be sold in supplements.

Uses & effectiveness

People take products containing methylsynephrine hoping to burn fat, lose weight, boost energy, and improve workouts. These are popular marketing claims, not proven facts.

There is no reliable human evidence showing methylsynephrine safely helps with weight loss or exercise performance when used as a supplement. The available information mostly comes from older use as a blood-pressure drug and from reports of harm, not from quality studies supporting supplement uses. Because of safety concerns and its illegal status in supplements, it should not be relied on for any of these purposes.

How it works

Methylsynephrine is a sympathomimetic, meaning it acts like the body's natural "fight or flight" chemicals (adrenaline and noradrenaline). It can stimulate receptors that increase heart rate, raise blood pressure, and speed up metabolism.

Because of these effects, it was historically used to treat low blood pressure. The same stimulant action is the reason it is added to fat-burner and energy products. However, these stimulant effects also explain why it can stress the heart and circulation, which is the main safety concern.

Safety & precautions

Methylsynephrine is not considered safe for use as a dietary supplement. The FDA and other authorities have flagged products containing it, and it appears on banned-substance lists for athletes (for example, under the World Anti-Doping Agency as oxilofrine).

People with heart disease, high blood pressure, irregular heartbeats, anxiety, thyroid problems, or who take other stimulants are at especially high risk and should not use it. Athletes risk failing drug tests. Pregnant or breastfeeding people should avoid it completely because it is an unapproved stimulant with no safety data. If you find this ingredient on a product label, talk with a pharmacist or doctor before using it — and it is generally safest to avoid it altogether.

Side effects

Reported and expected side effects relate to its stimulant nature and may include rapid or pounding heartbeat, high blood pressure, chest pain, headache, dizziness, nausea, vomiting, anxiety, and trouble sleeping.

More serious problems have been reported, including dangerous heart rhythm changes, very high blood pressure, fainting, and cardiac events, particularly when combined with other stimulants such as caffeine. Seek emergency care for chest pain, severe shortness of breath, fainting, or an irregular or racing heartbeat.

Methylsynephrine: Reported Adverse Effects

Documented safety reports on Methylsynephrine from the evidence-graded Natural Medicines (TRC Healthcare) database, shown word-for-word from the licensed record.

There is currently a limited amount of information available about the adverse effects of methylsynephrine. Orally, it has been reported to cause increased blood pressure, palpitations, and arrhythmia.

  1. Pawar RS, Grundel E. Overview of regulation of dietary supplements in the USA and issues of adulteration with phenethylamines (PEAs). Drug Test Anal 2017;9:500-517.
  2. Cohen PA, Avula B, Venhuis B, Travis JC, Wang YH, Khan IA. Pharmaceutical doses of the banned stimulant oxilofrine found in dietary supplements sold in the USA. Drug Test Anal. 2017;9(1):135-142.
Reports by condition
Arrhythmia Cardiovascular

Orally, methylsynephrine has been reported to cause increased blood pressure, palpitations, and arrhythmias.

In the Netherlands, the supplement dexaprine was removed from the market because of reported cases of tachycardia, palpitations, chest pain, and a single report of cardiac arrest. As little as half a tablet was associated with these adverse effects, which occurred within one hour of ingestion. Dexaprine was found to contain methylsynephrine, synephrine, deterenol, yohimbine, caffeine, theophylline, and possibly beta-methyl-beta-phenylethylamines. Therefore, it is unclear if these effects were due to methylsynephrine, the other ingredients, or the combination.

  1. Pawar RS, Grundel E. Overview of regulation of dietary supplements in the USA and issues of adulteration with phenethylamines (PEAs). Drug Test Anal 2017;9:500-517.
  2. Cohen PA, Avula B, Venhuis B, Travis JC, Wang YH, Khan IA. Pharmaceutical doses of the banned stimulant oxilofrine found in dietary supplements sold in the USA. Drug Test Anal. 2017;9(1):135-142.
  3. 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;6(6):578-81.
Nausea and vomiting Gastrointestinal

In the Netherlands, the supplement dexaprine was removed from the market following reported cases of nausea and vomiting. As little as half a tablet was associated with these adverse effects, which occurred within one hour of ingestion. Dexaprine was found to contain methylsynephrine, synephrine, deterenol, yohimbine, caffeine, theophylline, and possibly beta-methyl-beta-phenylethylamines. Therefore, it is unclear if these effects were due to methylsynephrine, the other ingredients, or the combination.

  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;6(6):578-81.
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.

Adverse-effects data: Natural Medicines, Therapeutic Research Center

Dosing

There is no established safe or approved dose of methylsynephrine for use as a dietary supplement, and we will not suggest one. It is not a legal supplement ingredient in the United States.

Supplement labels may list it under different names (such as oxilofrine or methylsynephrine) and amounts can be inconsistent or unreliable. The safest choice is to avoid products that contain it. If you are unsure about an ingredient on a label, ask your pharmacist or doctor before taking the product.

Pregnancy & Breastfeeding

Methylsynephrine & Pregnancy

Insufficient reliable information

Insufficient reliable information available; avoid using.

Methylsynephrine & Breastfeeding

Insufficient reliable information

Insufficient reliable information available; 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

Pregnancy & lactation ratings: Natural Medicines, Therapeutic Research Center

References & further reading

The 3 references that drive our Methylsynephrine 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. Pawar RS, Grundel E. Overview of regulation of dietary supplements in the USA and issues of adulteration with phenethylamines (PEAs). Drug Test Anal 2017;9:500-517. PubMed
  2. Cohen PA, Avula B, Venhuis B, Travis JC, Wang YH, Khan IA. Pharmaceutical doses of the banned stimulant oxilofrine found in dietary supplements sold in the USA. Drug Test Anal. 2017;9(1):135-142. PubMed
  3. 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;6(6):578-81. PubMed
Keep reading

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.

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

Brand directory

Brands that make products with Methylsynephrine

26 brands in our database make a supplement containing Methylsynephrine.

Product directory

Supplement products with Methylsynephrine

55 products in our database contain Methylsynephrine. Open any to see its full ingredient list and every drug interaction we check.

Pharmacist Counseling Corner

Methylsynephrine: Common Questions

Does Methylsynephrine interact with prescription medications?
Yes. We list 191 medications with a known interaction with Methylsynephrine. Use the checker above to see how Methylsynephrine interacts with a specific drug.
How are Methylsynephrine interactions rated?
Each interaction is graded major, moderate, or minor based on how clinically significant it is and the strength of the evidence behind it. Major interactions are the most serious and are best avoided, or used only under close professional supervision.
Is it safe to take Methylsynephrine with my medications?
It depends on the specific medication. Some combinations are fine, while others call for monitoring, timing changes, or should be avoided. Check your exact drug above and confirm with your pharmacist or doctor before starting, stopping, or changing anything.
Where does this Methylsynephrine interaction information come from?
Our interaction data is built on the Natural Medicines database — an evidence-graded reference for vitamins, herbs, and supplements — and is reviewed by licensed HelloPharmacist pharmacists, who may add clinical context.
What is Methylsynephrine used for?
It is marketed in some weight-loss and pre-workout supplements for fat burning and energy, but these uses are not proven, and it is not a legal supplement ingredient in the U.S.
Is Methylsynephrine safe to take?
No. It is a stimulant linked to heart and blood pressure problems, and regulators warn against its use in supplements, so it is best avoided.
Is Methylsynephrine the same as synephrine?
No. Although the names are similar, Methylsynephrine (oxilofrine) is a different, more potent synthetic stimulant, not the same as the synephrine found in bitter orange.
Can athletes use Methylsynephrine?
No. It is banned in sports (listed by the World Anti-Doping Agency as oxilofrine) and can cause a failed drug test.

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

Keep exploring

Products that contain Methylsynephrine

A rotating sample of real supplements in our database that list Methylsynephrine — open any to see its full ingredients and every drug interaction we check.

See all 55 products with Methylsynephrine →
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