What medication is good for a child 10 years and up, to use for constipation?

Constipation: If increasing fibe and water intake r in the diet is not helpful, MiraLAX (polyethylene glycol) is a stool softener (not a laxative despite it's name) that is very helpful. I would start with 1/2 capful mixed in water or juice/day and increase the dose gradually every 3-4 days until a moderately soft stool every day or two is achieved.