Fe: Inhibited absorption w/ Mg trisilicate, antacids & ingestion of eggs or milk. Vit B
12: Reduced absorption from the GIT w/ aminoglycosides, aminosalicylic acid, anticonvulsants, biguanides, chloramphenicol, cholestyramine, cimetidine, colchicine, K salts, & methyldopa. Decreased serum conc w/ OCs.