Acute oral toxicity of capsaicin in mice and rats

The oral toxicity of capsaicin was investigated in mice and rats. Oral LD50 values were 118.8 mg/kg for male and 97.4 mg/kg for female mice, and 161.2 mg/kg for male and 148.1 mg/kg for female rats. Major toxic symptoms in mice were salivation, erythema of skin, staggering gait, bradypnea and cyanosis. Some animals showed tremor, clonic convulsion, dyspnea and lateral or prone position and then died 4 to 26 min after dosing. Survivors recovered within 6 hr in mice and 24 hr in rats. Toxic symptoms of rats were almost the same as mice, but rats showing higher incidence of cyanosis, clonic or tonic convulsion, dyspnea and lateral position, and the recovery was later than mice. The cause of death by capsaicin may be due to hypotension and respiratory paralysis in both animals, although the pathophysiology of death is not clearly understood. At pathological examination, erosion and ulcer of gastric fundus were seen in dead animals, while no pathological change was seen in surviving ones.