Based on the experience with gliclazide, the following adverse effects have been reported.
The most frequent adverse reaction with gliclazide is hypoglycaemia. As for other sulphonylureas, treatment with gliclazide tablets can cause hypoglycaemia, if mealtimes are irregular and, in particular, if meals are skipped. Possible symptoms of hypoglycaemia are headache, intense hunger, nausea, vomiting, lassitude, sleep disorders, agitation, aggression, poor concentration, reduced awareness and slowed reactions, depression, confusion, visual and speech disorders, aphasia, tremor, paresis, sensory disorders, dizziness, feeling of powerlessness, loss of self-control, delirium, convulsions, shallow respiration, bradycardia, drowsiness and loss of consciousness, possibly resulting in coma and lethal outcome.
In addition, signs of adrenergic counter-regulation may be observed: sweating, clammy skin, anxiety, tachycardia, hypertension, palpitations, angina pectoris and cardiac arrhythmia. Usually, symptoms disappear after intake of carbohydrates (sugar). However, artificial sweeteners have no effect.
Experience with other sulphonylureas shows that hypoglycaemia can recur even when measures prove effective initially. If a hypoglycaemic episode is severe or prolonged and even if it is temporarily controlled by intake of sugar, immediate medical treatment or even hospitalization are required.
Other adverse effects: Gastrointestinal disturbances:
Abdominal pain, nausea, vomiting, dyspepsia, diarrhoea and constipation have been reported. If these should occur, they can be avoided or minimized if gliclazide is taken before breakfast.
The following undesirable effects have been more rarely reported: Skin and subcutaneous tissue disorders:
Rash, pruritus, urticaria, angioedema, erythema, maculopapular rashes, and bullous reactions (such as Stevens-Johnson syndrome and toxic epidermal necrolysis) and exceptionally, drug rash with eosinophilia and systemic symptoms (DRESS).
Blood and lymphatic system disorders:
Changes in haematology are rare. They may include anaemia, leukopenia, thrombocytopenia, granulocytopenia. These are in general reversible upon discontinuation of medication.
Raised hepatic enzyme levels (AST, ALT, alkaline phosphatase), hepatitis (isolated reports). Discontinue treatment if cholestatic jaundice appears. These symptoms usually disappear after discontinuation of treatment.
Transient visual disturbances may occur especially on initiation of treatment, due to changes in blood glucose levels.
Class attribution effects:
Cases of erythrocytopenia, agranulocytosis, haemolytic anaemia, pancytopenia, allergic vasculitis and hyponatraemia, have been described for other sulphonylureas. With other sulphonylureas, cases were also observed of elevated liver enzyme levels and even impairment of liver function (e.g. with cholestasis and jaundice) and hepatitis which regressed after withdrawal of the sulphonylurea or led to be life-threatening liver failure in isolated cases.