GI bleeding. Patients w/ chronic bronchial asthma or resp failure. Avoid concomitant use w/ systemic disulfiram & metronidazole. Not recommended during pregnancy (especially during 1st trimester) & lactation. Paradoxical resp adverse effects including increased bronchial secretions leading to hospitalization in infants & childn 2.5-34 mth. Contraindicated in infants & childn <2 yr. Not recommended for childn <12 yr.