Backward flow of urine from the bladder into the kidney is known as vesicoureteral reflux, or simply reflux. Although many children simply grow out of this condition, some have more complicated disease. In its most severe forms, urinary reflux can cause kidney damage. Children with low-grade reflux without any other abnormalities are most likely to improve over time.

Preventing and treating urinary-tract infections is one of the goals of therapy. Antibiotics are the most commonly prescribed treatments. Urinary reflux is made worse by constipation. That is why laxatives are used in children with urinary reflux.

MiraLax (also known as polyethylene glycol) is a laxative that is usually used to cleanse the bowel in people about to undergo surgery or a colonoscopy or sigmoidoscopy. MiraLax is also used to treat people with chronic constipation. It works by keeping water in the bowel that would otherwise be absorbed. Unlike other laxatives like mineral oil, MiraLax does not seem to cause any problem with drug absorption and should not interfere with absorption of nutrients.