Some people experience major side effects. Neither my wife (semaglutide) nor I (tirzepatide) have had any negative effects apart from minor upper GI disturbances when moving up to a higher dose. These dissipate within a week or so.

That said, these are definitely serious drugs and I wouldn't be taking one if my quality and length of life weren't threatened by metabolic syndrome, and if I hadn't been trying for decades to solve the problem without medication.