boost optimum with 5 in 1 advanced nutrition helps support muscle, energy, bone, normal immune function, and vision. boost optimum. be up for life. with recurring constipation and belly pain if you feel like you spend too much time in the bathroom talk to your doctor and say yesss! to linzess. ♪ yesss! linzess treats adults with ibs with constipation or chronic constipation. linzess can help relieve your belly pain, and lets you have more frequent and complete bowel movements. linzess is not a laxative. it works differently to help you get ahead of your recurring constipation and belly pain. do not give linzess to children less than 6, and it should not be given to children 6 to less than 18. it may harm them. do not 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.