The most common side effects are gastrointestinal: nausea, constipation, bloating, and occasional vomiting, particularly during dose escalation. More serious but rare risks include pancreatitis, gallbladder disease, and, based on animal studies, a theoretical risk of thyroid C-cell tumors, which is why semaglutide is contraindicated in patients with a personal or family history of medullary thyroid carcinoma. Dr. Rodriguez reviews your complete medical history specifically to screen for these risks before prescribing.