My 2 1/2 yr old son started taking Xyzal about 2 wks ago for his skin allergies. I started giving him Miralax OTC per his Ped. Dr. because he became very constipated. I'm also trying to potty-train him and thought he might have been just holding it in. I also thought he might have a UTI b/c he would grab his private area & complain that it hurt to tee-tee. He was cathaterized last Wednesday & had an x-ray of the bowels. I'm just wondering if this is a side effect usually seen in toddlers? He's never had constipation like this before starting the Med. I'm concerned about continuing with the medicine.