Because of the low levels of quinine in breastmilk, amounts ingested by the infant are small and would not be expected to cause any adverse effects in breastfed infants. The dosage in milk is far below those required to treat an infant for malaria.[1] However, quinine should not be used in mothers with an infant who is glucose-6-phosphate dehydrogenase (G6PD) deficient.[2] Even the relatively small amounts of quinine in tonic water ingested by the mother have caused hemolysis in G6PD-deficient infants.