The first signs and symptoms appear after 1-3 hours.
Neuromuscular disturbances are the most prominent.
Impairment of consciousness ranging in severity to deep coma. Convulsions, especially in small children. Motor restlessness, muscular twitching, tremor , athetoid movements opisthotonos, ataxia, drowsiness , dizziness , mydriasis , nystagmus , adiadochokinesia, ballism, psychomotor disturbances, dysmetria. Initial hyperreflexia , followed by hyporeflexia. Isolated instances of overdosage have included leukocytosis, reduced leukocyte count, glycosuria and acetonuria.