In 1954 Chalmers and Boheimer reported that the drug was associated with megaloblastic anemia. Between 1954 and 1957, twenty-one cases of megaloblastic anemia associated with primidone and/or phenytoin were reported. In most of these cases the anemia was due to vitamin deficiencies: usually folic acid deficiency; in one case Vitamin B12 deficiency and in one case Vitamin C deficiency. Some cases were associated with deficient diets: one patient ate mostly bread and butter, another ate bread, buns, and hard candy, and another could rarely be persuaded to eat in the hospital.