The global rise in overweight and obesity presents a formidable public health challenge, placing immense strain on healthcare systems worldwide and driving demand for effective weight management solutions, including those sought by international patients. As individuals increasingly consider various healthcare destinations for specialized treatments, understanding the nuanced profiles of pharmacological interventions becomes paramount. Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) have emerged as powerful tools in combating obesity, yet their associated gastrointestinal side effects can significantly influence patient adherence and satisfaction, a critical factor for those undertaking patient travel for treatment.

The Global Challenge of Obesity and Pharmacological Solutions

Overweight and obesity have reached epidemic proportions, impacting individual well-being and imposing substantial economic burdens on global healthcare infrastructure. These conditions are deeply intertwined with numerous comorbidities, from cardiovascular disease to type 2 diabetes mellitus (T2DM) and certain cancers, underscoring the urgent need for comprehensive management strategies. While lifestyle modifications and dietary interventions form the bedrock of weight management, pharmacological agents are increasingly vital when these alone prove insufficient.

GLP-1 RAs have garnered considerable attention for their efficacy in promoting weight loss among individuals with overweight or obesity. These agents operate through multiple pathways, primarily by stimulating the GLP-1 receptor, which enhances insulin secretion, suppresses glucagon release, slows gastric emptying, and fosters a sense of satiety. Consequently, GLP-1 RAs are not only effective in glycemic control but also demonstrate profound effects on body weight. A diverse array of GLP-1 RAs is currently available or under development, including both short-acting and long-acting formulations, dual agonists like tirzepatide, and novel oral agents such as orforglipron.

Despite their undeniable therapeutic benefits, GLP-1 RAs are frequently associated with a range of adverse events, particularly gastrointestinal disturbances. These issues are a significant concern for patients, potentially impacting their commitment to treatment and overall satisfaction with their healthcare experience. Symptoms can include nausea, vomiting, diarrhea, and abdominal discomfort, varying in both severity and duration. For international patients seeking treatment abroad, such side effects could significantly complicate their patient travel experience and overall perception of the quality of care received at a particular healthcare destination.

While the precise mechanisms behind these gastrointestinal disturbances are not fully understood, they are thought to arise from the effects of GLP-1 RAs on gastrointestinal motility and secretion. Much of the existing research on the safety and efficacy of GLP-1 RAs has traditionally focused on populations with T2DM, where underlying disease pathology could potentially confound gastrointestinal symptoms. This left a critical gap in understanding the specific incidence and impact of these adverse events in non-diabetic individuals with overweight and obesity receiving GLP-1 RAs solely for weight loss purposes. This systematic review and dose-response network meta-analysis aimed to fill this void, providing crucial insights into the safety profile of GLP-1 RAs in this distinct and growing patient population.

Unpacking Gastrointestinal Adverse Events: A Critical Review

Our analysis, conducted according to the 2020 PRISMA guidelines, involved a meticulous search of PubMed and EMBASE databases to identify relevant evidence. The objective was to evaluate gastrointestinal adverse events linked to GLP-1 RAs in non-diabetic individuals with overweight or obesity. The search spanned from inception up to December 20, 2023, without geographical or language restrictions, ensuring a comprehensive dataset. Two independent authors assessed study eligibility and extracted data, resolving any discrepancies through consensus.

Methodological Rigor in Assessing GLP-1 RA Safety

Inclusion criteria focused on interventional human studies, such as clinical trials and randomized controlled trials, specifically examining GLP-1 RA-associated gastrointestinal adverse events in non-diabetic patients with overweight or obesity. The scope also extended to agents with overlapping mechanisms, like tirzepatide (a dual GIP/GLP-1 RA) and cagrilintide (a long-acting amylin analogue), due to their increasing relevance in obesity treatment. Exclusion criteria eliminated studies involving T2DM patients, as well as non-original research formats like editorials, case reports, and systematic reviews. The Cochrane Collaboration’s tool was utilized to evaluate the risk of bias in included randomized controlled trials, ensuring a robust assessment of study quality.

Ultimately, the review incorporated 39 articles, encompassing a substantial cohort of 33,354 individuals. These studies were geographically diverse, with significant contributions from the United States (13 studies), Denmark (9 studies), China (4 studies), Slovenia (4 studies), Canada (3 studies), and others. This broad representation is vital for the medical tourism sector, as it offers a more generalizable understanding of GLP-1 RA effects across different populations, informing international patient care strategies.

Key Findings: Gastrointestinal Side Effect Profiles of GLP-1 RAs

Our network meta-analysis illuminated the specific gastrointestinal adverse events associated with various GLP-1 RAs in non-diabetic individuals with overweight or obesity. This detailed breakdown is particularly valuable for healthcare providers and international patients making informed decisions about treatment and potential healthcare destinations.

Nausea: A Pervasive Concern

Nausea emerged as a consistently reported adverse effect across nearly all evaluated GLP-1 RAs, with 29 trials contributing to this analysis. All agents demonstrated a statistically significant increase in the risk of nausea. Orforglipron presented the highest relative risk (RR 4.7748), followed by liraglutide (RR 3.0919), semaglutide (RR 2.9464), tirzepatide (RR 2.8997), exenatide (RR 2.6645), and cagrilinitide (RR 2.2983). From an editorial perspective, this pervasive risk highlights the need for robust patient education and proactive management strategies, particularly for international patients who might be far from their primary care support systems. Effective management of nausea can significantly enhance the patient travel experience and adherence to treatment.

Vomiting: Differentiating Agent Risks

Out of 23 trials, the risk of vomiting varied significantly among GLP-1 RAs. Tirzepatide showed the highest relative risk (RR 13.2265), followed by semaglutide (RR 4.2108), liraglutide (RR 3.8722), and orforglipron (RR 3.8722), all demonstrating a significant increase. Conversely, cagrilinitide (RR 1.3701) and exenatide (RR 4.5238) did not show a statistically significant increase in vomiting risk. This differentiation is crucial for tailoring treatment plans, especially for patients with a lower tolerance for emetic side effects, which could severely disrupt their daily lives or patient travel plans.

Diarrhea and Constipation: Balancing Efficacy with Comfort

Twenty-four trials examined diarrhea risk. Semaglutide (RR 1.7714), liraglutide (RR 1.8231), and tirzepatide (RR 3.3537) were associated with a significant increase in diarrhea. Notably, exenatide (RR 0.1756), cagrilinitide (RR 1.1956), and orforglipron (RR 2.2973) did not show a significant increased risk. For constipation, also assessed in 24 trials, semaglutide (RR 2.0979), liraglutide (RR 2.2368), and tirzepatide (RR 3.3575) were linked to a significant increase. Cagrilinitide (RR 1.2782) and exenatide (RR 5.0000) did not show a significant increase, while orforglipron (RR 4.0541) did. These findings underscore the importance of considering individual patient bowel habits and preferences when selecting a GLP-1 RA, a key aspect of personalized international patient care.

Less Common but Notable GI Disturbances

Beyond the primary symptoms, the review also assessed less frequent gastrointestinal adverse events:

  • Abdominal Distension: Only semaglutide (RR 1.4245) showed a significant increase in risk across 11 trials. Liraglutide and exenatide did not.
  • Upper Abdominal Pain: Liraglutide (RR 1.6919) and semaglutide (RR 2.1435) were associated with a significant increase in upper abdominal pain risk, according to 13 trials. Exenatide did not show a similar increase.
  • Abdominal Pain: Liraglutide (RR 2.077), semaglutide (RR 2.3447), and tirzepatide (RR 4.3604) were linked to a significant increase in overall abdominal pain risk across 12 trials. Orforglipron did not.
  • Abdominal Discomfort: Only one trial evaluated liraglutide (RR 0.5474), finding no significant increased risk.
  • Gastroesophageal Reflux Disease (GERD): Semaglutide (RR 2.4321) was the sole agent, among 8 trials, associated with a significant increase in GERD risk. Liraglutide, tirzepatide, and orforglipron did not show a significant increase.
  • Eructation (Belching): Liraglutide (RR 3.2373) and semaglutide (RR 7.8838) demonstrated a significant increased risk across 11 trials. Exenatide, tirzepatide, and orforglipron did not.
  • Flatulence: Semaglutide (RR 1.4005) and tirzepatide (RR 2.4164) were associated with a significant increased risk across 8 trials. Liraglutide did not.
  • Decreased Appetite: Semaglutide (RR 3.0190), cagrilinitide (RR 3.0684), and liraglutide (RR 3.0404) were all linked to a significant increased risk of decreased appetite across 6 trials. Tirzepatide and orforglipron did not show a significant increase. While decreased appetite is often a desired effect in weight management, an excessive or uncomfortable reduction can impact quality of life.

For other adverse events, including cholelithiasis, gallstone-related complications, cholecystitis, acute cholecystitis, acute pancreatitis, viral gastroenteritis, hard feces, and infrequent bowel movements, no significant increased risk was observed across the limited number of trials evaluating them. This is a reassuring finding for medical tourism patients concerned about more severe, albeit rarer, complications, though ongoing vigilance and reporting are always warranted to maintain high quality of care standards.

The Impact of Dosage: A Dose-Response Analysis

The dose-response network meta-analysis further clarified that increasing doses of GLP-1 RAs correlated with a heightened risk of nausea, vomiting, diarrhea, constipation, and decreased appetite. A common pattern observed was a rapid increase in adverse effects at lower dosages, often followed by a plateauing tendency at higher doses. However, exenatide presented a linear increase in vomiting risk even at very high values. The precision of estimates was notably higher for liraglutide and semaglutide, indicated by narrower confidence intervals. This dose-dependent relationship is a critical consideration for clinicians, particularly when guiding international patients through titration protocols, emphasizing the need for careful monitoring and adjustment to optimize both efficacy and tolerability during their patient travel and recovery periods.

Quality of Evidence and Study Limitations: Considerations for International Patient Care

The quality assessment, utilizing the Cochrane Collaboration’s tool, revealed varying levels of bias across the included articles. While 13 articles demonstrated a low risk of bias across all domains, a substantial number presented unclear risks, particularly concerning selection bias (random sequence generation and allocation concealment) in 14 articles, and blinding in 13 articles. Furthermore, 10 studies showed a high risk of bias in blinding related to performance and detection. These limitations are crucial for global healthcare providers to acknowledge when interpreting results and communicating potential risks to international patients, ensuring transparency and realistic expectations regarding quality of care.

It is an editorial opinion that the heterogeneity in study design, patient populations, GLP-1 RA dosage regimens, and follow-up durations represents a significant limitation, potentially affecting the consistency and interpretation of gastrointestinal adverse events. The limited data for certain adverse events (e.g., viral gastroenteritis, hard feces) also restricted robust statistical analysis. Confounding factors like concomitant medications and baseline gastrointestinal conditions could have influenced reported adverse event incidence and severity. The absence of stratified data by treatment duration, age, and disease status (especially for diabetes comparison) further limits the generalizability of findings, particularly important for a diverse international patient care demographic. The geographic concentration of studies (e.g., US, Denmark, China) also raises questions about the global applicability of these findings to other ethnic groups and regions, a key concern for medical tourism operators. Future research should prioritize addressing these limitations to provide a more comprehensive understanding for healthcare destinations worldwide.

Despite these limitations, the study’s strengths are noteworthy. Its methodological rigor, extensive literature review, and the application of advanced network meta-analysis and dose-response network meta-analysis techniques offer broader comparative insights than traditional methods. The exclusive focus on GLP-1 RA gastrointestinal adverse effects in non-diabetic adults with overweight or obesity ensures high relevance and direct applicability to this specific patient population. This is, to our knowledge, the first network meta-analysis specifically addressing this group, distinguishing it from previous evaluations predominantly conducted in diabetic patients. This targeted approach significantly enhances the clarity and utility of the results for the evolving landscape of global healthcare.

Strategic Implications for Global Healthcare and Medical Tourism Providers

The findings from this comprehensive review carry significant strategic implications for healthcare providers, particularly those operating within the medical tourism sector. As the demand for effective weight management solutions continues to drive patient travel, understanding the tolerability profiles of GLP-1 RAs becomes a cornerstone of quality of care and patient satisfaction.

Personalizing Treatment for Enhanced Patient Travel Experience

Our analysis strongly supports a personalized approach to selecting GLP-1 RAs for weight management in non-diabetic individuals. The clinical relevance of gastrointestinal adverse events extends beyond mere incidence; their severity, duration, and impact on a patient’s quality of life are paramount. Even mild but persistent symptoms can lead to treatment discontinuation, especially for international patients who may have a lower threshold for tolerability, given the additional complexities of patient travel and being away from home. Discontinuation rates due to gastrointestinal side effects in diabetic populations are reported to be 10–20%, and we believe similar or potentially higher rates could be observed in non-diabetic settings or among international patients.

For medical tourism providers, this emphasizes the need for:

  • Shared Decision-Making: Engaging international patients in discussions that weigh efficacy goals against tolerability concerns is crucial. This proactive approach supports informed choices and sets realistic expectations for the patient travel experience.
  • Gradual Dose Titration: Implementing careful and gradual dose titration protocols, coupled with close monitoring, can significantly mitigate adverse effects and improve adherence, contributing to a positive international patient care journey.
  • Patient Education: Comprehensive education about potential side effects, how to manage them, and when to seek medical advice is indispensable. This empowers international patients to navigate their treatment effectively, even when in a foreign healthcare destination.

The Role of Transparent Reporting in Healthcare Destination Selection

For patients with concerns about gastrointestinal discomfort, agents with lower associated risks, such as cagrilinitide, may be preferable. Conversely, patients prioritizing maximal weight loss who demonstrate higher tolerability for adverse effects might benefit more from agents like semaglutide or tirzepatide. This level of detail in adverse event profiles is invaluable for healthcare destinations aiming to attract and serve international patients. Transparent reporting of expected outcomes and potential side effects is a hallmark of high-quality care and builds trust with global healthcare consumers.

From a strategic standpoint, healthcare providers in the medical tourism sector should leverage this data to:

  • Develop Specialized Programs: Tailor weight management programs that consider the diverse needs and tolerability profiles of international patients, enhancing the appeal of their healthcare destination.
  • Enhance Pre-Travel Consultations: Incorporate detailed discussions about GLP-1 RA side effects during initial consultations, preparing patients for their patient travel and treatment journey.
  • Invest in Post-Treatment Support: Offer robust follow-up and support mechanisms for international patients to manage side effects, even after they return home, reinforcing a commitment to comprehensive international patient care.

Future Directions for Research and Patient-Centric Care

Future research is essential to further refine our understanding of GLP-1 RA adverse events. Investigations into underlying mechanisms and the development of targeted mitigation strategies are vital. Moreover, trials with stratified data by age, disease status, and treatment duration will be instrumental in personalizing prescribing practices. For the medical tourism industry, this means an ongoing commitment to evidence-based practice and continuous improvement in the quality of care offered to international patients seeking wellness tourism and medical interventions.

Bottom Line: Navigating GLP-1 RA Tolerability in Cross-Border Healthcare

This comprehensive study offers critical insights into the gastrointestinal adverse events associated with GLP-1 RAs in non-diabetic individuals with overweight or obesity. Nausea, vomiting, diarrhea, and constipation are the most frequently reported side effects, with varying risk profiles across different agents. Orforglipron, liraglutide, semaglutide, and tirzepatide generally showed higher risks for nausea and vomiting, while cagrilinitide and exenatide appeared to have a more favorable profile for vomiting and diarrhea. The dose-response analysis confirmed that higher doses generally increase the risk of these adverse effects, often with a rapid onset at lower doses before plateauing.

For clinicians and global healthcare providers, particularly those involved in cross-border healthcare, these findings underscore the imperative of a personalized treatment approach. Balancing the therapeutic benefits of GLP-1 RAs with their potential for gastrointestinal discomfort is key to optimizing patient adherence and satisfaction. This is especially true for international patients, where a positive patient travel experience and effective international patient care are paramount. As medical tourism continues to grow, healthcare destinations that prioritize transparent communication, tailored treatment plans, and robust support for managing side effects will solidify their reputation for quality of care in the competitive global healthcare landscape.

The news signal for this article was referred from: https://www.nature.com/articles/s41366-025-01859-6