Hi Some kids develop constipation after Iron formulations. Give him plenty of fluids like plain water/ juices/ coconut water/ soups etc. Give him plenty of fresh fruits and vegetables. Fibre and fluids are the things which will help him pass soft stools. In case if he does not pass stool even after the above said measures, then he might need Stool softeners like Lactulose. Suppositories of glycerine can also be used. Please get your doctor s advice before using these medications. Hope my answer helps. Best wishes.