Symptoms: severe pain in the oral cavity, along the esophagus, in the abdomen, vomiting, diarrhea; mucous membrane of the oral cavity and pharynx - edematic, dark brown, violet, laryngeal edema possible, development of mechanical asphyxia, burn shock, motor excitement, seizures, parkinsonism, hemorrhagic colitis, nephropathy, hepatopathy. With reduced acidity of gastric juice, the development of methemoglobinemia with pronounced cyanosis and respiratory distress is possible. The lethal dose for children is about 3 g, for adults 0.3-0.5 g / kg.
Treatment: methylene blue (50 ml of 1% solution), ascorbic acid (in / in - 30 ml of a 5% solution), cyanocobalamin - up to 1 mg, pyridoxine (in / m - 3 ml of 5% solution).