Anti-Obesity Drugs: What EM Physicians Need to Know

Obesity is a global health challenge. 1 in 8 people in the world live with obesity.1

Adult obesity has doubled since the 1990s and adolescent obesity quadrupled. In many countries, being overweight or obese has become as concerning as malnutrition under-fives. Traditional weight-loss approaches, such as diet, exercise, and surgery, have shown variable success. It is therefore unsurprising that pharmacological solutions—particularly GLP-1 receptor agonists—have seen such rapid adoption. Their use in non-diabetics has risen by a staggering 700% in the US between 2019 and 2023.2

Despite its popularity, barriers exist – high costs, limited supply, and lack of a structured multidisciplinary obesity programs make their use challenging for many patients. As emergency physicians, we need to understand these challenges and be familiar with their side effects, complications, or concerns related to their use/ availability.

What Are GLP-1 Receptor Agonists and How Do They Work?

They were initially developed as diabetes treatments but have more recently been repurposed for obesity management. Multiple studies suggest these medications are associated with a 15% reduction in weight in just 1–2 years.3 Many of these drugs are commonly known by their brand name, which has been described in the table below.

Table 1 – Adapted form: Long B, Pelletier J, Koyfman A, Bridwell RE. GLP-1 agonists: a review for emergency clinicians. The American Journal of Emergency Medicine. 2024 Apr 1;78:89-94

Mechanism of action

• GLP-1 is an incretin hormone produced from the L cells of the small intestine that binds to the GLP-1 receptor (GLP-1R).
• GLP-1 potentiates post prandial insulin release when glucose levels rise after meals and reduce the gastric emptying time. It directly acts on the CNS to control hunger and increases feelings of satiety.
• GLP-1 agonists are also associated with reducing cardiovascular adverse events and MACE by improving ejection fraction, coronary blood flow, and cardiac output.2,3
• Tirzepatide (Mounjaro) is a dual receptor agonist for GLP-1 and glucose-dependent insulinotropic polypeptide (GIP).

Image 1 via Education tools, Smart Servier Medical Art

Who should not use them?

People who develop a serious hypersensitivity reaction and pregnant or breastfeeding patients should not be prescribed these drugs. They are not recommended in those with personal or family history of multiple endocrine neoplasia 2A, multiple endocrine neoplasia 2B, or medullary thyroid cancer due to concern for long-term thyroid effects.3

Side Effects and their Implications in the ED

• Gastrointestinal Side effects

Mild gastrointestinal side effects are most common with patients experiencing nausea (25-40%), vomiting, diarrhoea, or constipation.3,4 Rarer, more serious presentations include pancreatitis, bowel obstruction, gallbladder disease, which should be actively managed in the ED.3,5

• Hypersensitivity reaction

These reactions are commonly associated with self-limiting or antihistaminic responsive pruritic rash. ‘Ozempic face’ is due to sagging / wrinkling of the skin is a dermatological manifestation of rapid weight loss and rather than skin reaction.

• Metabolic complications -electrolyte and glucose abnormalities

Electrolyte disturbances and hypoglycaemia are common side effects in both diabetic and non-diabetic patients.

Hypoglycaemia can occur with GLP-1 agonists, especially if used alongside sulfonylureas or insulin.3 Diabetics on GLP-1 Agonists can also present with episodes of hyperglycaemia and DKA.3 In such cases, it is important to look beyond the acute management and consider whether problems with regular access to medication is a contributing factor. Discuss how patients source their medicines especially as standard supplies maybe unavailable, costly, resulting in use of unlicensed pharmacies or skipped doses.

• Ocular side effects

There is a reported increased risk of diabetic retinopathy with GLP-1 agonists, specifically semaglutide (Ozempic, Wegovy) as demonstrated by the SUSTAIN-6 trial (HR 1.76; 95% CI 1.11 to 2.78).3,6 Based on these findings ED clinicians should consider a thorough ophthalmic assessment in these patients presenting with painless visual loss or vision changes with Ophthalmology referral.

• Procedural Sedation and Endotracheal intubation

GLP-1 agonists delay gastric emptying, increasing the risk of aspiration. Systematic reviews of studies conducted in perioperative patients taking GLP-1 agonists found larger volumes of solid food in the stomach even after adequate fasting preoperatively and a higher rate of  (post operative nausea and vomiting.7,8 The ASA also recommend withholding GPL-1 agonists preoperatively.9 Emergency clinicians should treat these patients as higher risk during procedural sedation or intubation and prepare accordingly.

Social and Economic Issues

 There is currently a lack of structured systems to support patients prescribed these “game-changer” medications. In December 2024, NICE recommended the use of tirzepatide (Mounjaro), alongside semaglutide (Wegovy) and liraglutide (Saxenda), for the treatment of weight-related comorbidities.10 NICE recommended these drugs alongside diet and exercise, yet many patients lack structured programs offering nutritional, behavioural, and psychological support. As a result, some present to the emergency department without proper follow-up or guidance.

High costs, limited insurance or NHS coverage, and global shortages create inequities, which lead some patients to turn towards unregulated online sources, risking safety.10,11 Emergency physicians play a key role in recognizing these patterns, reinforcing the importance of multidisciplinary care, and guiding patients toward safe, evidence-based weight management.

References

1. World Health Organization (WHO). Obesity and overweight [Internet]. WHO, 8 Dec 2025.
2. Mahase E. GLP-1 agonists: US sees 700% increase over four years in number of patients without diabetes starting treatment. BMJ. 2024 Jul 23;386:q1645.
3. Long B, et al. GLP-1 agonists: A review for emergency clinicians. Am J Emerg Med. 2024 Apr;78:89-94.
4. Liu L, Li Z, Ye W, et al. Safety and effects of anti-obesity medications on weight loss, cardiometabolic, and psychological outcomes in people living with overweight or obesity: a systematic review and meta-analysis. EClinicalMedicine. 2024 Dec 27;79:103020.
5. Perreault L, Reid TJ. Obesity in adults: drug therapy. UpToDate, Last updated: 2026.
6. Marso SP, Bain SC, et al. Semaglutide and Cardiovascular Outcomes in Patients with Type 2 Diabetes. N Engl J Med. 2016 Nov 10;375(19):1834-1844.
7. do Nascimento TS, Pereira ROL, et al. The impact of glucagon-like peptide-1 receptor agonists in the patients undergoing anesthesia or sedation: systematic review and meta-analysis. Perioper Med (Lond). 2024 Jul 22;13(1):78.
8. Dixon W. Use of Glucagon-Like Peptide-1 Agonists and Increased Risk of Procedural Sedation and Endotracheal Intubation in the Emergency Department. Ann Emerg Med. 2024 Aug;84(2):226-227.
9. Joshi GP, et al. American Society of Anesthesiologists consensus-based guidance on preoperative management of patients (adults and children) on glucagon-like peptide-1 (GLP-1) receptor agonists. Last updated: June. 2023 Jun 29;29.
10. Fruh SM. Obesity: Risk factors, complications, and strategies for sustainable long-term weight management. J Am Assoc Nurse Pract. 2017 Oct;29(S1):S3-S14.
11. Fallows E, Ells L, Anand V. Semaglutide and the future of obesity care in the UK. Lancet. 2023 Jun 24;401(10394):2093-2096.