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Summary sheet: 4-Methylaminorex
Chemical Nomenclature
Common names 4-Methylaminorex, 4-MAR, 4-MAX, U4Euh, Ice
Systematic name 4-Methyl-5-phenyl-4,5-dihydro-1,3-oxazol-2-amine
Class Membership
Psychoactive class Stimulant
Chemical class Substituted aminorex
Routes of Administration

WARNING: Always start with lower doses due to differences between individual body weight, tolerance, metabolism, and personal sensitivity. See responsible use section.

Threshold x mg
Light x - x mg
Common x - x mg
Strong x - x mg
Heavy x mg +
Total x - x hours
Onset x - x minutes

DISCLAIMER: PW's dosage information is gathered from users and resources for educational purposes only. It is not a recommendation and should be verified with other sources for accuracy.

4-Methylaminorex (4-MAR, 4-MAX) is a stimulant drug of the 2-amino-5-aryloxazoline class that was first synthesized in 1960 by McNeil Laboratories.[1] It is also known by its street names "U4Euh" ("Euphoria") and "Ice". It is banned in many countries as a stimulant.

4-Methylaminorex has effects comparable to methamphetamine but with a longer duration.


4-Methylaminorex exists as four stereoisomers - (±)-cis and (±)-trans. The (±)-cis isomers are the form used recreationally. The (±)-cis isomers [racemate (1:1-mixture) of the (4R,5S)-isomer and the enantiomeric (4S,5R)-isomer] generally synthesized from dl-phenylpropanolamine in one step by cyclization with cyanogen bromide (sometimes prepared in situ by reacting sodium cyanide with bromine). Alternate synthesis routes generally involve more steps, such as replacing cyanogen bromide with sodium or potassium cyanate to form an intermediate and then reacting it with concentrated hydrochloric acid. A method reported in microgram replaced the need for a separate addition of hydrochloric acid by starting with the hydrochloride salt of the dl-phenylpropanolamine but side-products are noted. The (±)-trans isomers [racemate (1:1-mixture) of the (4S,5S)-isomer and the enantiomeric (4R,5R)-isomer] are synthesized in the same manner above but dl-norephedrine is used as the starting material instead. The cyanate reaction proceeds differently from the cyanogen bromide and transforms norephedrine into trans-4-methylaminorex instead. The cyanogen bromide, by comparison, transformed norephedrine into the cis isomer and norpseudoephedrine into the trans isomers of the final product.


It produces long-lasting effects, generally up to 16 hours in duration if taken orally and up to 12 hours if smoked or insufflated. Large doses have been reported anecdotally to last up to 36 hours. The effects are stimulant in nature, producing euphoria, an increase in attention, and increased cognition. Anecdotally, it has been reported to produce effects similar to nootropics, however, there is no research to support the claim that it is any different or more effective than other psychostimulants in this respect. Moreover, 4-methylaminorex does not have the established safety profile of widely used clinical psychostimulants such as methylphenidate and dextroamphetamine.[citation needed]

Subjective effects

3-FA is considered to be a potent and complex stimulant with mild entactogenic undertones when compared to other substances its class, like 4-FA. However, it does not have the productivity and focus-enhancing effects often claimed by users of 2-FA or 2-FMA which has had the effect of limiting its appeal.

Disclaimer: The effects listed below cite the Subjective Effect Index (SEI), an open research literature based on anecdotal user reports and the personal analyses of PsychonautWiki contributors. As a result, they should be viewed with a healthy degree of skepticism.

It is also worth noting that these effects will not necessarily occur in a predictable or reliable manner, although higher doses are more liable to induce the full spectrum of effects. Likewise, adverse effects become increasingly likely with higher doses and may include addiction, severe injury, or death ☠.

Experience reports

There are currently 0 experience reports which describe the effects of this substance in our experience index.

Additional experience reports can be found here:

Toxicity and harm potential

There has been one reported death due to 4-methylaminorex and diazepam. Concentrations of 4-methylaminorex were: in blood 21.3 mg/L; in urine 12.3 mg/L. Diazepam concentration in blood was 0.8 mg/L.[2] One rat study[3] has studied excretion of 4-methylaminorex in urine: "The concentration of trans-4-methylaminorex in rat urine following four injections of the trans-4S,5S isomer (5 mg/kg i.p each, at intervals of 12 h in 2 days, as measured quantitatively by GC/MS" The same study has studied pharmacokinetics and tissue distribution of the stereoisomers of 4-methylaminorex in rats.

"Pulmonary hypertension has been associated with ingestion of the appetite suppressant aminorex. A similar compound, 4-methylaminorex was discovered on the property of three individuals with diagnoses of pulmonary hypertension."

Tolerance and addiction potential

As with other stimulants, the chronic use of 4-Methylaminorex can be considered moderately addictive with a high potential for abuse and is capable of causing psychological dependence among a certain population of users. When dependence or addiction has developed, cravings and withdrawal effects may occur if a person suddenly stops their usage.

Tolerance to many of the effects of 4-Methylaminorex develops with prolonged and repeated use. This results in users having to administer increasingly large doses to achieve the same effects. After that, it takes about 3 - 7 days for the tolerance to be reduced to half and 1 - 10 days to be back at baseline (in the absence of further consumption). 4-Methylaminorex presents cross-tolerance with all dopaminergic stimulants, meaning that after the consumption of 4-Methylaminorex all stimulants will have a reduced effect (especially including atypical stimulants one might not expect, like MDMA due to its reliance on dopamine and norepinephrine to exert its full euphoric effect).

Given its close equipotency to methamphetamine, it likely shares similar toxicity profiles, though this has yet to be scientifically validated.


Main article: Stimulant psychosis

Abuse of compounds within the amphetamine chemical class at high dosages for prolonged periods of time can potentially result in a stimulant psychosis that may present with a variety of symptoms (e.g., paranoia, hallucinations, or delusions).[4] A review on treatment for amphetamine, dextroamphetamine, and methamphetamine abuse-induced psychosis states that about 5–15% of users fail to recover completely.[5][6] The same review asserts that, based upon at least one trial, antipsychotic medications effectively resolve the symptoms of acute amphetamine psychosis.[7] Psychosis very rarely arises from therapeutic use.[8][9]

Dangerous interactions


This dangerous interactions section is a stub.

As such, it may contain incomplete or invalid information. You can help by expanding upon or correcting it.

Warning: Many psychoactive substances that are reasonably safe to use on their own can suddenly become dangerous and even life-threatening when combined with certain other substances. The following list provides some known dangerous interactions (although it is not guaranteed to include all of them).

Always conduct independent research (e.g. Google, DuckDuckGo, PubMed) to ensure that a combination of two or more substances is safe to consume. Some of the listed interactions have been sourced from TripSit.

Legal status

  • Australia: In Australia, 4-Methylaminorex is listed as Schedule 9, making it legal only for scientific and medical research.[12]
  • Canada: In Canada, 4-Methylaminorex is listed as Schedule III.[13]
  • Netherlands: In the Netherlands, aminorex (4-methylaminorex is a designer drug 2014) is a List I drug of the Opium Law.[14] It is not approved by the CBG, and so it is designated as lacking any medical use.
  • United Kingdom: In the United Kingdom, 4-Methylaminorex is listed as Class A.[15]
  • United States: In the United States, (±)-cis-4-methylaminorex was placed in Schedule I of the Controlled Substances Act shortly after its emergence as a recreational drug in the mid-1980s.[16] Manufacturing the trans isomer required a different process than those encountered when the substance was first scheduled, and was believed less potent than the cis isomer with a much lower abuse potential. However, studies revealing the abuse potential of the 'trans' isomer[citation needed], coupled with the development of new clandestine synthetic methods that would produce the trans[citation needed] created a potential loophole in the law, which covered only the 'cis' isomer. To clarify the situation, the US Drug Enforcement Administration published a paper in its DEA Microgram Journal, regarding interpretation of the relevant statutory law as it relates to the status of trans-4-methylaminorex. In summary, according to this non-legally binding decision, trans-4-methylaminorex is not currently a controlled substance, but a potential analogue. In fact, the report explicitly states: The United States Drug Enforcement Administration has the following opinion on the legality of the positional isomer "trans"-4-methylaminorex, which, unlike its 'cis' isomer was never placed in any schedule under the Controlled Substances Act. However, the opinion does say that the agency considers the substance a potential controlled substance analogue, making the substance identical to a Schedule I substance if intended for human consumption, according to the Federal Analogue Act. The report gives an account of a successful conviction under the Federal Analogue Act of an offense involving the trans isomer.[17]
    • Florida: "2-Amino-4-methyl-5-phenyl-2-oxazoline (4-methylaminorex)" and "any material, compound, mixture, or preparation that contains any quantity of" it "or that contains any of [its] salts, isomers, including optical, positional, or geometric isomers, and salts of isomers, if the existence of such salts, isomers, and salts of isomers is possible" is a Schedule I controlled substance in the state of Florida making it illegal to buy, sell, or possess in Florida.[18]

See also

External links


  1. 2-amino-5-aryloxazoline compositions and methods of using same |
  2. A fatality involving U4Euh, a cyclic derivative of phenylpropanolamine. |
  3. Detection and assay of cis- and trans-isomers of 4-methylaminorex in urine, plasma and tissue samples. |
  4. Treatment for amphetamine psychosis | [1]
  5. Treatment for amphetamine psychosis | [2]
  6. Hofmann FG (1983). A Handbook on Drug and Alcohol Abuse: The Biomedical Aspects (2nd ed.). New York: Oxford University Press. p. 329. ISBN 9780195030570.
  7. Treatment for amphetamine psychosis | [3]
  8. Stimulant Misuse: Strategies to Manage a Growing Problem |
  10. Talaie, H.; Panahandeh, R.; Fayaznouri, M. R.; Asadi, Z.; Abdollahi, M. (2009). "Dose-independent occurrence of seizure with tramadol". Journal of Medical Toxicology. 5 (2): 63–67. doi:10.1007/BF03161089. eISSN 1937-6995. ISSN 1556-9039. OCLC 163567183. 
  11. Gillman, P. K. (2005). "Monoamine oxidase inhibitors, opioid analgesics and serotonin toxicity". British Journal of Anaesthesia. 95 (4): 434–441. doi:10.1093/bja/aei210Freely accessible. eISSN 1471-6771. ISSN 0007-0912. OCLC 01537271. PMID 16051647. 
  12. "Poisons Standard 2009". Retrieved 2009-09-02. 
  13. "Controlled Drugs and Substances Act". Retrieved 2009-09-02. 
  14. "Bijlage 1 Lijst I Opiumwetmiddelen". Archived from the original on 2009-06-25. Retrieved 2009-09-02. 
  16. "Section 1308.11 Schedule I". Archived from the original on 27 August 2009. Retrieved 2009-09-02. 
  17. Synthesis of trans-4-Methylaminorex from Norephedrine and Potassium Cyanate (DEA Microgram Journal)
  18. Florida Statutes - Chapter 893 - DRUG ABUSE PREVENTION AND CONTROL