Folic acid intolerance

Common but usually transient side effects are lethargy, incoordination, blurred vision, higher cortical dysfunction, and drowsiness. At concentrations greater than 50 mcg/mL, phenytoin can exacerbate seizures. Chronic side effects include gingival hyperplasia, impaired cognition, hirsutism, vitamin D deficiency, osteomalacia, folic acid deficiency, carbohydrate intolerance, hypothyroidism, and peripheral neuropathy. 

Like oral iron, parenteral iron is used too widely. When iron is truly needed, oral administration is generally preferable (9). Intractable gastrointestinal intolerance to oral formulations, hyperemesis in pregnancy, very severe blood loss, and possibly ulcerative colitis are some of the few valid indications for parenteral iron. A low ironbinding capacity (for example due to prior saturating iron therapy or malnutrition), folic acid deficiency, and an allergic constitution predispose the patient to adverse reactions to parenteral iron. Iron injections have been reported to provoke hemolytic anemia in cases of paroxysmal nocturnal hemoglobinuria. 

Gastrointestinal Severe intolerance to folic acid in a patient with Crohn s disease has been described [12 ]. 

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