 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. Learn more at Linzess.com or call 1-800-LIN-Z-E-S-S. Now! WNTC, Ashland City. And W285-FB, Bellevue. Now, more memories with the greatest hits of all time. WNTC-Bellevue.