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Systematic (IUPAC) name
CAS Number 94-07-5
ATC code C01CA08 (WHO) S01GA06
PubChem CID 7172
Chemical data
Formula C9H13NO2
Molar mass 167.205 g/mol[[Script error: No such module "String".]]
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Synephrine (or oxedrine) is a drug commonly used for weight loss. While its effectiveness is widely debated, synephrine has gained significant popularity as an alternative to ephedrine, a related substance which has been made illegal or restricted in many countries due to health risks and its use as a precursor in the illicit manufacturing of methamphetamine. Products containing bitter orange or synephrine are suspected of causing adverse cardiovascular reactions [1]. Synephrine is derived primarily from the fruit of Citrus aurantium, a relatively small citrus tree, of which several of its more common names include Bitter Orange, Sour Orange, and Zhi shi. Dietary supplements generally supply single oral doses of 3–30 mg, while as a pharmaceutical agent it is given orally or by parenteral injection in 20–100 mg doses as a vasoconstrictor to hypotensive patients.[2]


  • Burns fat
  • Increases energy
  • Increases metabolism
  • Promotes weight loss
  • Increases body heat

Synephrine and neosynephrine

There has been some confusion surrounding synephrine and phenylephrine (neosynephrine), one of its positional isomers. The chemicals are similar in structure; the only difference is the location of the aromatic hydroxyl group. In synephrine, the hydroxyl is at the para position, whereas in neosynephrine it is at the meta position. Each compound has differing biological properties.

Associated risks

Many diet products such as "Stacker 2", "Xenadrine-EFX", etc. contain a "stack" of synephrine along with caffeine, sometimes with an NSAID. Some reports have indicated that such diet pills cause numerous harmful effects. The Mayo Clinic published a report that suggested a link between Stacker 2 pills and increased risk of ischemic stroke, increased blood pressure, and myocardial infarction (heart attack).

Synephrine can also cause arrhythmias [5]. It is similar to ephedrine [5] and can therefore show similar symptoms (see ephedrine adverse effects).

Following the presentation of a healthy young man with a myocardial infarction, a case study and subsequent literature review found that the makers of "nutritional supplements" who replaced ephedrine with its analogs p-synephrine and/or p-octopamine from "bitter orange" had in effect simply found a loophole in the FDA's April 2004 regulation banning ephedra in those supplements by substituting a similar substance the regulation did not address, while permitting them to label the products as "ephedra-free".[6]

Natural occurrence

It is reported as naturally occurring in the following species: Coryphanta cornifera, C. durangensis, C. elephantides, C. greenwoodii, C. ottonis, C. pectinata, C. poselgeriana, C ramillosa, C. runyonii, Dolichothele sphaerica, D. surculosa, D. uberiformis.[7]


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  2. Baselt RC (2008). Disposition of Toxic Drugs and Chemicals in Man (8th ed.). Foster City, California: Biomedical Publications. pp. 1471–2. ISBN 9780962652370. 
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  5. 5.0 5.1 Livsmedelsverket (Swedish FDA)
  6. Thomas JE, Munir JA, McIntyre PZ, Ferguson MA (2009). "STEMI in a 24-year-old man after use of a synephrine-containing dietary supplement : a case report and review of the literature". Tex Heart Inst J. 36 (6): 586–90. PMC 2801940Freely accessible. PMID 20069086. 
  7. Shulgin, Alexander & Shulgin, Ann (1997). Page 671. Tihkal: The Continuation. Berkeley: Transform Press. ISBN 0963009699 .

External links


it:Sinefrina ja:シネフリン pl:Synefryna sv:Synefrin zh:辛弗林