Patients w/ diabetes & those prone to recurrent renal calculi (eg, dialysis patients) should not take excess doses (as little as 100 mg daily) for extended periods of time.
Large doses may cause diarrhea, GI disturbances, hyperoxaluria & formation of renal Ca oxalate calculi.
Drug Interactions
Enhanced Fe absorption from GI tract. May increase contraceptive effect of OC. May decrease fluphenazine levels. May decrease anticoagulant effect of warfarin.