Hi! Welcome to Healthcaremagic. I read your query. Usually this medicine is taken for 2-4 weeks but since doctor prescribed it for son, surely he must have weighed its uses for him.Generally prolonged use doesnot cause any severe symptoms. Occasionally it might cause nausea, abdominal cramps, flatulence or diarrhoea. In that case refer to your physician immediately. I would reccommend you to stick to the exact prescribed dose and mix it well in full glass of water. Take care of his fluid intake and diet. Add more fibours to his diet. Go for regular follow up visit with the doctor and check if dose can be tapered slowly. Hope this answer helps you. Thank you!