Summary of gastrointestiopnal disorders of patietns treated with GLP-1 agonists
Summary of Gastrointestinal Disorders in Patients Treated with GLP-1 Agonists
1. Overview: why gastrointestinal effects are expected
Glucagon-like peptide-1 receptor agonists (GLP-1RAs)—including liraglutide, semaglutide, dulaglutide, exenatide, lixisenatide—and related incretin therapies such as tirzepatide and cagrilintide–semaglutide are widely used for type 2 diabetes and obesity. Their gastrointestinal effects are not incidental; they are closely tied to their therapeutic mechanism. GLP-1RAs enhance glucose-dependent insulin secretion, suppress glucagon, reduce appetite through central satiety pathways, and slow gastric emptying, which blunts postprandial glucose excursions and contributes to weight loss (Rosen, 2026). Short-acting GLP-1RAs such as exenatide twice daily and lixisenatide have particularly strong and sustained effects on gastric emptying, whereas long-acting agents such as liraglutide, dulaglutide, and semaglutide show tachyphylaxis, with gastric-emptying effects decreasing over time (Nauck, 2020); (Meier, 2012).
Across clinical trials and real-world studies, adverse effects from GLP-1RAs are predominantly gastrointestinal, most often nausea, vomiting, diarrhea, constipation, abdominal pain, dyspepsia, and symptoms related to delayed gastric emptying (Rosen, 2026). These events are usually mild to moderate, occur most frequently during dose escalation, and often lessen with continued treatment.
2. Common gastrointestinal adverse events
Nausea, vomiting, diarrhea, constipation, and abdominal pain
The most consistently reported gastrointestinal disorders are nausea and other “digestive” symptoms. A JAMA review of anti-obesity medications summarized that nutrient-stimulated hormone-based therapies—including liraglutide, semaglutide, and tirzepatide—are associated with nausea in 28%–44% of patients, diarrhea in 21%–30%, and constipation in 11%–24% (Gudzune, 2024). These rates are clinically important because they often determine adherence and tolerability.
In the SURPASS-2 trial comparing tirzepatide with semaglutide in 1879 patients with type 2 diabetes, gastrointestinal events were the most common adverse events and were mainly mild to moderate. Nausea occurred in 17%–22% of tirzepatide-treated patients and 18% of semaglutide-treated patients; diarrhea occurred in 13%–16% versus 12%; and vomiting in 6%–10% versus 8%, respectively (Frías et al., 2021). Serious adverse events occurred in 5%–7% of tirzepatide recipients and 3% of semaglutide recipients, although the provided text does not specify how many serious events were gastrointestinal.
In adolescents receiving once-weekly semaglutide 2.4 mg for obesity, gastrointestinal adverse events occurred in 62% of semaglutide-treated participants versus 42% with placebo (Weghuber et al., 2022). This indicates that GI tolerability issues are not limited to adults.
Combination or higher-potency incretin-based therapies appear to have substantial GI-event burdens. In a phase 3 trial of cagrilintide–semaglutide in 3417 adults with overweight or obesity, gastrointestinal adverse events—including nausea, vomiting, diarrhea, constipation, and abdominal pain—affected 79.6% of participants receiving the combination compared with 39.9% receiving placebo; most events were transient and mild to moderate (Garvey et al., 2025).
3. Delayed gastric emptying, retained gastric contents, and aspiration risk
Mechanistic basis
Delayed gastric emptying is one of the defining gastrointestinal actions of GLP-1RAs. It reduces postprandial glycemic excursions and may reduce chylomicron formation and triglyceride absorption, but it can also cause clinically relevant problems such as retained gastric contents before endoscopy or anesthesia (Jalleh, 2024). The issue is especially important because long-acting GLP-1RAs and tirzepatide have long half-lives, and withholding them for a short period may not fully normalize gastric motility.
Procedural implications
Retained gastric contents during upper gastrointestinal endoscopy are reported more frequently among GLP-1RA users, although pulmonary aspiration appears rare in the available evidence (Jalleh, 2024). Current pre-procedural recommendations remain uncertain because the evidence base is limited, particularly for long-acting GLP-1RAs (Jalleh, 2024). Factors complicating guidance include: long drug half-lives, GLP-1’s ability to slow emptying even at physiological concentrations, tachyphylaxis with prolonged exposure, and the observation that people with slow baseline gastric emptying may experience less additional slowing after treatment initiation (Jalleh, 2024).
Potential mitigation strategies include longer fasting periods for solids, point-of-care gastric ultrasound to identify retained gastric contents, and prokinetic agents such as erythromycin, although these approaches require further study (Jalleh, 2024).
4. Treatment discontinuation due to gastrointestinal disorders
GI symptoms are a major cause of stopping therapy. In the LEADER cardiovascular outcomes trial of liraglutide in 9340 patients with type 2 diabetes and high cardiovascular risk, the most common adverse events leading to liraglutide discontinuation were gastrointestinal (Marso et al., 2016). In semaglutide-treated patients with obesity and knee osteoarthritis, permanent discontinuation occurred in 6.7% with semaglutide versus 3.0% with placebo, with gastrointestinal disorders the most common reason (Bliddal et al., 2024).
For the oral GLP-1RA orforglipron, adverse events led to discontinuation in 5.3%–10.3% of participants receiving orforglipron versus 2.7% receiving placebo in a 72-week obesity trial; the most common adverse events were gastrointestinal and mostly mild to moderate (Wharton et al., 2025). In early type 2 diabetes, permanent discontinuation due to adverse events occurred in 4.4%–7.8% with orforglipron versus 1.4% with placebo, again with mild-to-moderate GI events mainly during dose escalation (Rosenstock et al., 2025).
Real-world data also show high discontinuation: 20%–50% of patients stop GLP-1RA therapy within the first year, with nausea and digestive problems among the key contributors, along with cost and suboptimal dosing (Thomsen et al., 2025).
5. Biliary disease, gallstones, pancreatitis, and severe GI outcomes
Biliary events are less common than nausea or diarrhea but are clinically relevant. In the STEP TEENS trial, cholelithiasis occurred in 5 semaglutide-treated adolescents, representing 4%, and in no placebo-treated participants (Weghuber et al., 2022). This may relate to rapid weight loss as well as incretin-related biliary effects, although causality cannot be fully assigned from the provided data.
Pancreatitis remains a concern historically associated with incretin therapies, but the evidence summarized here does not show a clear excess risk. In LEADER, pancreatitis was nonsignificantly lower in the liraglutide group than in the placebo group (Marso et al., 2016). A real-world evidence review similarly found frequent gastrointestinal disturbances but no clear increase in severe outcomes such as pancreatitis, pancreatic cancer, thyroid disorders, depression, or self-harm (Thomsen et al., 2025).
Possible rare complications related to impaired motility—such as bowel obstruction—are mentioned as theoretical or observed concerns, but the available evidence is limited and does not provide robust incidence estimates (Jalleh, 2024).
6. Dose, potency, and comparative safety considerations
Higher-dose and more potent agents may increase concern for gastrointestinal intolerance. A 2024 BMJ network meta-analysis of 76 randomized trials involving 39,246 participants and 15 GLP-1RA drugs concluded that GLP-1RAs are effective for glycemic control and weight loss but highlighted safety concerns for gastrointestinal adverse events, especially with high-dose administration (Yao et al., 2024). In obesity trials, tirzepatide and semaglutide produce substantial weight loss, and the most common adverse events in both groups are gastrointestinal, generally mild to moderate and concentrated during dose escalation (Aronne et al., 2025). In a real-world propensity-matched cohort of 18,386 adults with overweight or obesity, tirzepatide produced greater weight loss than semaglutide, but rates of gastrointestinal adverse events were similar between groups (Rodriguez et al., 2024).
Conclusion
Gastrointestinal disorders are the dominant adverse-effect class in patients treated with GLP-1 agonists and related incretin therapies. The most common events are nausea, vomiting, diarrhea, constipation, and abdominal pain, typically mild to moderate and most prominent during dose escalation. Mechanistically, delayed gastric emptying is central to both efficacy and adverse effects; it improves postprandial glycemia but can lead to retained gastric contents during anesthesia or endoscopy, creating procedural-management challenges. Less common but clinically important concerns include gallstones, rare aspiration events, possible bowel obstruction, and pancreatitis surveillance, although current evidence does not show a clear increase in pancreatitis risk. Overall, GI tolerability is a major determinant of dose escalation, persistence, and real-world effectiveness of GLP-1RA therapy.