Precaution should be taken in patients with symptoms/history of gastro-intestinal disease, impaired hepatic, cardiac or renal function, pregnancy, porphyria and patients who are taking diuretics, anticoagulant, or anti-diabetics. During prolonged treatment, periodical monitoring of liver function should be carried out and blood counts are recommended. Possibility of hypersensitivity reactions to sodium disulphite particularly in patients with asthma.