If the patient (or someone else) swallow a lot of tablets at the same time, or he/she thinks a child may have swallowed any, contact the nearest hospital casualty department or tell the doctor immediately. Symptoms of an overdose include fast regular heart beat, dilated pupils, drowsiness, coma, difficulty breathing, jerky movements, hot dry skin, dry mouth and tongue, difficulty passing water, intestinal blockage, uncontrolled eye movement.