Manifestations of acute dapsone intoxication include vomiting, cyanosis, tachypnea, tachycardia, altered or depressed mental status, and seizures. Methemoglobinemia and sulfhemoglobinemia usually are observed within a few hours of the overdose, but intravascular hemolysis may be delayed. The illness lasts several days. Clinical manifestations are more severe in patients with underlying medical conditions that may contribute to hypoxemia.