linzess works differently from laxatives. linzess treats adults with ibs with constipation or chronic constipation. it can help relieve your belly pain, and lets you have more frequent and complete bowel movements that are easier to pass. do not give linzess to children less than six, and it should not be given to children six to less than eighteen. it may harm them. don't take linzess if you have a bowel blockage. get immediate help if you develop unusual or severe stomach pain, especially with bloody or black stools. the most common side effect is diarrhea, sometimes severe. if it's severe stop taking linzess and call your doctor right away. other side effects include gas, stomach-area pain and swelling. talk to your doctor about managing your symptoms proactively with linzess.