Primaquine toxicity

Primaquine is usually well tolerated but may cause gastrointestinal distress, pruritus, headaches, and methemoglobinemia. More serious toxicity involves hemolysis in G6PD-deficient patients. Primaquine is contraindicated in pregnancy. Other toxic manifestations observed after large doses of the drug include abdominal discomfort, especially when administered in combination with chloroquine (which may affect patient compliance), and occasional methemoglobinemia. Granulocytopenia and agranulocytosis are rarely seen, except in patients with lupus or arthritis, because both conditions are aggravated by the drug. All Plasmodium species may develop resistance to primaquine.