Hello, My Grandson Is Nearly 10 And Has Trouble With

Hello,
My grandson is nearly 10 and has trouble with constipation since birth. I know at times he will hold off going to the toilet if he is playing games etc. But when he does go after a few doses of medicine to help him go his stools are huge what would be the best thing to do to keep him going regularly I am not happy about him taking laxitives