Liraglutide Side Effects: What Studies Report

Evidence tier: Established. Liraglutide is a glucagon-like peptide-1 (GLP-1) receptor agonist marketed as an approved prescription medicine for type 2 diabetes and for weight management, and its adverse-event profile has been characterised in randomized controlled trials, in large healthcare-claims analyses and in pharmacovigilance databases. This page summarises what those published sources reported about harms and tolerability. This page is for educational purposes only and is not medical advice; consult a licensed physician about any medicine, symptom or treatment decision.

Brand names associated with liraglutide products are used here only to identify the medicines discussed in the literature; each name is a trademark of its owner, and PeptideU is not affiliated with or endorsed by any manufacturer or trademark holder. No product is offered, supplied or recommended anywhere on this site.

Where liraglutide safety data come from

Safety information about an approved medicine accumulates from several different evidence streams, and each has distinct strengths and blind spots:

• Randomized controlled trials record adverse events prospectively in defined populations, with placebo comparison, but they enrol limited numbers of participants over limited periods.
• Observational and claims-based cohort studies capture much larger populations and rarer outcomes, but cannot fully exclude confounding.
• Pharmacovigilance databases collect spontaneous case reports, which can flag signals but cannot establish incidence or causation.
• Narrative and systematic reviews synthesise the above; a 2024 review of GLP-1 receptor agonists for obesity summarised weight-loss outcomes alongside tolerability, side effects and risk topics (Obesity Pillars, 2024).

Mechanistic work has been used to explain why several of these events cluster in the digestive system: a 2024 mechanistic review described liraglutide and semaglutide as acting through GLP-1 receptor signalling that slows gastric emptying and modulates central appetite pathways (Frontiers in Nutrition, 2024), effects that researchers have linked to the gastrointestinal complaints recorded in trials.

Gastrointestinal Adverse Events: What Studies Report

Across the published literature, digestive symptoms were the most frequently recorded adverse events. In the LEAN phase 2 trial, which administered liraglutide 1.8 mg once daily for 48 weeks to patients with non-alcoholic steatohepatitis, researchers reported diarrhoea in 38% of the liraglutide group versus 19% of the placebo group, constipation in 27% versus 4%, and loss of appetite in 31% versus 8% (Lancet, 2016). The study characterised these events as mostly transient and mild to moderate.

A 2024 review of GLP-1 receptor agonists used for obesity likewise described nausea, vomiting, diarrhoea and constipation as the dominant tolerability issues reported in the trial literature, and noted that such events were a common reason participants stopped treatment (Obesity Pillars, 2024). For comparison, a review of the semaglutide STEP programme reported that gastrointestinal events were also the most common adverse events with that agent and were typically mild to moderate and transient (Postgraduate Medicine, 2022).

Why gastrointestinal events matter for interpretation

Because these symptoms are common, they dominate discontinuation statistics in randomized trials. A review of head-to-head clinical studies comparing GLP-1 receptor agonists reported that agents in this class differed in their tolerability as well as their glycaemic and weight effects, so findings for one molecule were not automatically transferable to another (Therapeutic Advances in Endocrinology and Metabolism, 2021).

Gallbladder, Pancreas and Bowel Signals: What Studies Report

Serious gastrointestinal outcomes have been studied separately from everyday nausea and diarrhoea. A 2023 population-based cohort analysis of patients dispensed GLP-1 receptor agonists for weight loss compared liraglutide and semaglutide users with bupropion-naltrexone users and reported adjusted hazard ratios of 9.09 for pancreatitis, 4.22 for bowel obstruction and 3.67 for gastroparesis, while the hazard ratio for biliary disease was 1.50 and not statistically significant (JAMA, 2023). Researchers presented these as relative risks in an observational design, not as absolute event rates for any individual.

Gallstone disease has also appeared in the case-report literature: a 2015 report described cholelithiasis occurring in association with liraglutide treatment and discussed the biliary risk considerations raised by the case (Aging Clinical and Experimental Research, 2015). Single case reports cannot quantify risk, but they are one of the mechanisms by which signals enter the wider literature and are later tested in cohort studies. The 2024 obesity-focused review similarly grouped biliary and pancreatic events among the risk topics requiring attention in the GLP-1 receptor agonist class (Obesity Pillars, 2024).

Psychiatric Case Reports: What Studies Report

Psychiatric outcomes attracted formal pharmacovigilance attention. A 2024 analysis of individual case safety reports submitted to the EudraVigilance database examined psychiatric adverse events associated with semaglutide, liraglutide and tirzepatide, and reported that the psychiatric reports catalogued for these agents included events such as depression, anxiety and suicidal ideation (International Journal of Clinical Pharmacy, 2024). The authors of that analysis framed their findings as signal detection from spontaneous reports, which by design cannot establish that the medicine caused the reported event, cannot supply denominators, and is subject to reporting bias and media-driven reporting surges.

Children and Adolescents: What Studies Report

Two randomized trials published in the New England Journal of Medicine examined liraglutide in young populations with obesity. In adolescents aged 12 to under 18 years, the study administered liraglutide at doses up to 3.0 mg once daily alongside lifestyle therapy for 56 weeks and reported that gastrointestinal adverse events occurred more often in the liraglutide group than the placebo group, with more participants in the liraglutide group discontinuing because of adverse events (NEJM, 2020).

In children aged 6 to under 12 years, a randomized trial administering liraglutide up to 3.0 mg once daily for 56 weeks reported that gastrointestinal adverse events were more frequent with liraglutide than with placebo, consistent with the pattern researchers had described in older age groups (NEJM, 2025). A 2025 review of GLP-1 receptor agonists and GIP/GLP-1 co-agonists in adolescents and in elderly patients discussed the additional safety considerations that arise at both ends of the age range, including tolerability and monitoring issues specific to those populations (Medicina Clínica, 2025).

What the studies reported, at a glance

Long-term safety: What Studies Report

Duration is a recurring limitation in the anti-obesity pharmacotherapy literature. A 2021 review of long-term efficacy and safety of anti-obesity treatment reported that although several agents demonstrated sustained weight effects in trials, the available follow-up periods constrained conclusions about long-term safety, and the review called for longer observation (Current Obesity Reports, 2021). The 2024 obesity review made a similar point about the GLP-1 receptor agonist class, describing both the magnitude of reported weight-loss outcomes and the open questions about risk over extended use (Obesity Pillars, 2024).

How to read these numbers without over-reading them

Several distinctions matter when comparing figures across the sources above:

1. Relative versus absolute risk. The hazard ratios reported in the 2023 cohort analysis described how often events occurred in one dispensed group compared with another, not the probability of the event in any given person (JAMA, 2023).
2. Signal versus incidence. The EudraVigilance analysis worked from spontaneous reports and therefore described patterns in reporting rather than measured event rates (International Journal of Clinical Pharmacy, 2024).
3. Population differences. Percentages from a 48-week trial in non-alcoholic steatohepatitis (Lancet, 2016) are not interchangeable with those from a 56-week paediatric obesity trial (NEJM, 2025), because the populations, comparators and endpoints differ.
4. Molecule differences. A review of head-to-head studies reported that GLP-1 receptor agonists differed from one another in efficacy and tolerability, so findings should be attributed to the specific agent studied (Therapeutic Advances in Endocrinology and Metabolism, 2021).

What the literature does not settle

The published record summarised here did not resolve several questions. Observational designs could not exclude residual confounding in the serious gastrointestinal outcome estimates (JAMA, 2023); spontaneous-report analyses could not determine whether psychiatric events were caused by treatment (International Journal of Clinical Pharmacy, 2024); and reviews of long-term anti-obesity pharmacotherapy reported that follow-up beyond a few years remained limited (Current Obesity Reports, 2021). Paediatric and geriatric use was described as an area where safety data were still accumulating (Medicina Clínica, 2025).

Liraglutide is a prescription medicine. Decisions about whether it is appropriate for a given person, how it is monitored, and what to do about any symptom belong to a licensed clinician who knows that person's history. Nothing on this page is a protocol, a recommendation or a substitute for that conversation. Readers who want the underlying pharmacology, trial history and mechanism explained step by step can work through the PeptideU liraglutide course, which teaches the background; this page stays focused on what the safety literature reported.

References

• Risk of Gastrointestinal Adverse Events Associated With Glucagon-Like Peptide-1 Receptor Agonists for Weight Loss (JAMA, 2023)
• Psychiatric adverse events associated with semaglutide, liraglutide and tirzepatide: a pharmacovigilance analysis of individual case safety reports submitted to the EudraVigilance database (International Journal of Clinical Pharmacy, 2024)
• Liraglutide safety and efficacy in patients with non-alcoholic steatohepatitis (LEAN): a multicentre, double-blind, randomised, placebo-controlled phase 2 study (Lancet, 2016)
• A Randomized, Controlled Trial of Liraglutide for Adolescents with Obesity (New England Journal of Medicine, 2020)
• Liraglutide for Children 6 to <12 Years of Age with Obesity - A Randomized Trial (New England Journal of Medicine, 2025)
• Glucagon-like Receptor-1 agonists for obesity: Weight loss outcomes, tolerability, side effects, and risks (Obesity Pillars, 2024)
• Liraglutide-related cholelithiasis (Aging Clinical and Experimental Research, 2015)
• Long-Term Efficacy and Safety of Anti-Obesity Treatment: Where Do We Stand? (Current Obesity Reports, 2021)
• GLP-1 receptor agonists: an updated review of head-to-head clinical studies (Therapeutic Advances in Endocrinology and Metabolism, 2021)
• Molecular mechanisms of semaglutide and liraglutide as a therapeutic option for obesity (Frontiers in Nutrition, 2024)
• GLP-1 receptor agonists and GIP/GLP-1 co-agonists in the treatment of obesity in adolescents and the elderly (Medicina Clínica, 2025)
• Efficacy and safety of semaglutide for weight management: evidence from the STEP program (Postgraduate Medicine, 2022)