G6PD Deficiency G6PD deficiency is the lack of glucose-6-phosphate dehydrogenase, an enzyme present in red blood cells, which can cause a type of anemia known as hemolytic anemia. Red blood cells carry oxygen in the body and G6PD protects these cells from natural oxygen chemicals (oxidative substances) that may build up. This may occur when you have a fever, take certain medications like pain medicines, certain antibiotics, and drugs to treat malaria, or when you are exposed to other specific substances, such as mothballs or fava beans. If there are too many of these chemicals, they can destroy the red blood cells prematurely.