Adverse Effects and Monitoring of GLP‑1 Receptor Agonists (Semaglutide and Tirzepatide)

Common Gastrointestinal Adverse Events

Nausea occurs in approximately 17–22 % of individuals treated with semaglutide. (American Society of Anesthesiologists) 1
Vomiting occurs in about 6–10 % of individuals treated with semaglutide. (American Society of Anesthesiologists) 1
Diarrhea occurs in roughly 12–16 % of individuals treated with semaglutide. (American Society of Anesthesiologists) 1
Gastro‑intestinal symptoms with semaglutide are usually transient and are less frequent with longer‑acting formulations; gradual dose escalation mitigates their occurrence. (American Society of Anesthesiologists; American College of Cardiology) [1][2]
Nausea is reported in 17–22 % of individuals receiving tirzepatide. (American College of Cardiology) 3
Diarrhea is reported in 13–16 % of individuals receiving tirzepatide. (American College of Cardiology) 3
Vomiting is reported in 6–10 % of individuals receiving tirzepatide. (American College of Cardiology) 3
Most gastrointestinal events with both agents are mild‑to‑moderate and tend to appear during dose escalation. (American College of Cardiology) 4

Both semaglutide and tirzepatide carry a warning for acute pancreatitis; patients should discontinue the drug and seek urgent care if severe, persistent abdominal pain develops. (American Diabetes Association) [5][6]
The LEADER trial of liraglutide (same drug class) did not demonstrate an increased risk of pancreatitis, and regulatory agencies have not confirmed a causal relationship. (American College of Cardiology) [7][2]

Class‑wide GLP‑1 receptor agonist therapy is associated with a higher incidence of acute cholecystitis. (American College of Cardiology) [8][2]

Semaglutide and tirzepatide are contraindicated in individuals with a personal or family history of medullary thyroid carcinoma or multiple endocrine neoplasia type 2, based on animal‑model data. (American College of Cardiology; Gastroenterology) [3][4]9

Semaglutide was linked to an increased rate of diabetic retinopathy complications in the SUSTAIN‑6 trial, likely related to rapid glucose lowering. (American College of Cardiology) [10][7]2
Patients should undergo a comprehensive eye examination within the prior 12 months before initiating therapy. (American College of Cardiology) [7][2]

When used as monotherapy, semaglutide and tirzepatide have a minimal intrinsic risk of hypoglycemia. (American Diabetes Association) [5][6]
Concurrent use with insulin markedly raises hypoglycemia risk. (American Diabetes Association) 5
Concurrent use with sulfonylureas increases hypoglycemia incidence by roughly 50 % compared with DPP‑4 inhibitor therapy. (American Diabetes Association) 6

Both agents should be prescribed with caution in individuals with severe renal impairment or end‑stage renal disease. (American College of Cardiology) [10][7]2

Modest increases in resting heart rate have been observed with both semaglutide and tirzepatide. (American College of Cardiology) [7][2]
Periodic monitoring of blood pressure and heart rate is recommended during therapy. (American College of Cardiology; Gastroenterology) [8][10]

GLP‑1 receptor agonists delay gastric emptying, which may increase aspiration risk during anesthesia. (American Society of Anesthesiologists) 1
The delay is more pronounced with short‑acting formulations. (American College of Cardiology) 2
Caution is advised for patients with a history of gastric or bariatric surgery when initiating therapy. (American College of Cardiology) [10][2]

Semaglutide is associated with a 38 % higher incidence of serious adverse events compared with placebo (risk ratio 1.38; 95 % CI 1.10–1.73). (American College of Cardiology; Gastroenterology) [4][9]

Monitor gastrointestinal symptoms, especially during dose titration. (Gastroenterology) 9
Screen for hypoglycemia when patients are also receiving insulin or sulfonylureas. (Obesity Reviews) 3
Observe for signs of acute gallbladder disease. (American College of Cardiology) 2
Educate patients to report pancreatitis‑related symptoms promptly. (Obesity Reviews) 3
Assess for suicidal ideation or behavior throughout treatment. (Obesity Reviews; Gastroenterology) [3][8]
Inspect injection sites for reactions at each visit. (Obesity Reviews; American College of Cardiology) [3][10]
Evaluate heart rhythm and rate; consider beta‑blockers if symptomatic tachycardia develops. (American Society of Anesthesiologists) 1