Drowsiness is the most common side effect, especially on high dosage. The others are disturbed coordination, fatigue, restlessness, confusion, nervousness, blurred vision, tinnitus, tremor, irritability, epigastric distress, photosensitivity, dryness of mouth, nose and throat, excessive perspiration, drug rash and hypotension. Haemolytic anaemia, agranulocytosis, headache, difficult urination and thickening of bronchial secretions are also reported.