The following adverse reactions have been observed, but there is not enough systematic collection of data to support an estimate of their frequency.
Gastrointestinal System Reactions: anorexia, gastric irritation, nausea, vomiting, cramping, diarrhea, constipation, jaundice (intrahepatic cholestatic jaundice), pancreatitis.
Central Nervous System Reactions: dizziness, vertigo, paresthesias, headache, xanthopsia.
Hematologic Reactions: leukopenia, agranulocytosis, thrombocytopenia, aplastic anemia.
Dermatologic-Hypersensitivity Reactions: purpura, photosensitivity, rash, urticaria, necrotizing angiitis (vasculitis)(cutaneous vasculitis), Lyell’s syndrome (toxic epidermal necrolysis).
Cardiovascular Reaction: Orthostatic hypotension may occur and may be aggravated by alcohol, barbiturates or narcotics.
Other Adverse Reactions: hyperglycemia, glycosuria, hyperuricemia, muscle spasm, weakness, restlessness, impotence.
Whenever adverse reactions are moderate or severe, chlorthalidone dosage should be reduced or therapy withdrawn.