Gastro-intestinal disturbances; reactions range from abdominal discomfort, nausea and vomiting, and abdominal pain to serious gastro-intestinal bleeding or activation of peptic ulcer. CNS-related side-effects include headache, dizziness, nervousness, tinnitus, depression, drowsiness and insomnia. Hypersensitivity reactions may occur occasionally and include fever and rashes. Hepatotoxicity and aseptic meningitis may also be hypersensitivity reactions. It can provoke bronchospasm in patients with asthma. It may cause cystitis and haematuria. It may also cause acute renal failure, interstitial nephritis, and nephrotic syndrome. Other adverse effects include anaemias, thrombocytopenia, neutropenia, eosinophilia, agranulocytosis, abnormalities in liver function tests, blurred vision, changes in visual colour perception, and toxic amblyopia. It should not be given to patients with active peptic ulceration. It should be given with care to the elderly, to patients with asthma or bronchospasm, bleeding disorders, cardio-vascular-disease, a history of peptic ulceration, and in liver or renal failure. Patients with congestive heart failure, cirrhosis, diuretic-induced volume depletion, or renal insufficiency are at greater risk of developing renal dysfunction due to NSAID-induced inhibition of renal prostaglandin synthesis. Care is required in those who are also receiving coumarin anticoagulants. Patients who are sensitive to aspirin or other NSAID's should generally not be given diclofenac. Diclofenac should be discontinued in patients who experience blurred or diminished vision, or changes in colour vision. Patients with collagen disease may be at increased risk of developing aseptic meningitis. In view of the product's inherent potential to cause fluid retention, heart failure may be precipitated in some compromised patients. When given together with preparations containing lithium or digoxin, diclofenac sodium may raise their blood concentrations.