Toxicological effects of a mixture used in weight loss products: p-synephrine associated with ephedrine, salicin, and caffeine

Int J Toxicol. 2012 Mar;31(2):184-91. doi: 10.1177/1091581811435708. Epub 2012 Mar 9.


p-Synephrine is an adrenergic amine found in Citrus aurantium L. fruits and has been used for weight loss in dietary supplements. There are commercial products containing this substance associated to caffeine, salicin, and ephedrine. The aim of this study was to evaluate the acute toxicity of this mixture in mice of both sexes. The significative results observed after acute oral administration to male and female mice of 300, 350, and 400 mg/kg total of p-synephrine, ephedrine, salicin, plus caffeine in a 10:4:6:80 w/w ratio included a reduction in locomotor activity and ptosis in all treated groups for both sexes. Seizures were also observed in male (400 mg/kg) and female groups (350 and 400 mg/kg). Gasping and tearing were observed in males. Salivation (400 mg/kg), agitation (350 and 400 mg/kg), and piloerection (all treated groups) were significantly observed only in females. Deaths occurred in males at 350 and 400 mg/kg treated groups and the necropsy showed cardiopulmonary hemorrhage. A reduction in locomotor activity was confirmed through the spontaneous locomotor activity test, in which the number of crossings considerably decreased (P < .01) in all treated groups. The rotarod test showed a decrease in motor coordination at 400 mg/kg. Body temperature decreased significantly (P < .01) in all treated groups compared to controls. The results suggested clear signs of toxicity of p-synephrine, ephedrine, salicin, and caffeine association; this toxicity augments the attentiveness on commercial products containing this mixture, given the expressive number of adverse events related to its utilization.

MeSH terms

  • Adrenergic Agents / toxicity
  • Animals
  • Anti-Obesity Agents / toxicity*
  • Ataxia / chemically induced
  • Benzyl Alcohols / toxicity*
  • Body Temperature
  • Caffeine / toxicity*
  • Central Nervous System Stimulants / toxicity
  • Drug Combinations
  • Ephedrine / toxicity*
  • Female
  • Glucosides / toxicity*
  • Male
  • Mice
  • Motor Activity / drug effects
  • Synephrine / toxicity*


  • Adrenergic Agents
  • Anti-Obesity Agents
  • Benzyl Alcohols
  • Central Nervous System Stimulants
  • Drug Combinations
  • Glucosides
  • Caffeine
  • salicin
  • Ephedrine
  • Synephrine