What are the adverse effects of semaglutide?

Adverse Effects of Semaglutide

Semaglutide's most common adverse effects are gastrointestinal—primarily nausea, vomiting, and diarrhea—which are typically mild-to-moderate and transient, occurring in the majority of patients. 1

Common Gastrointestinal Effects

The gastrointestinal adverse effects are the predominant concern with semaglutide therapy:

• Nausea, vomiting, and diarrhea are the most frequently reported adverse effects 1
• These effects occur due to delayed gastric emptying, a pharmacologic mechanism of GLP-1 receptor agonists 2
• Gradual dose titration significantly reduces the severity of these symptoms 1
• Gastrointestinal disorders account for approximately 30% of all adverse drug events with oral semaglutide and 28% with subcutaneous formulations 3
• Median onset for gastrointestinal symptoms is 4 days for both oral and subcutaneous formulations 3

Additional gastrointestinal effects include:

• Constipation 2
• Abdominal pain 2
• Dyspepsia, abdominal distension, eructation 4
• Gastroesophageal reflux disease 4

Serious Adverse Events

Pancreatitis

• Discontinue semaglutide immediately if pancreatitis is suspected and do not restart if confirmed 1
• GLP-1 receptor agonists as a class have been associated with increased pancreatitis risk 2
• In glycemic control trials, acute pancreatitis occurred in 0.3 cases per 100 patient-years with semaglutide versus 0.2 with comparators 5
• Semaglutide has not been studied in patients with a history of pancreatitis; consider alternative therapies in these patients 5

Gallbladder Disease

• Cholelithiasis (gallstones) and cholecystitis are established risks 2
• Cholelithiasis was reported in 1.5% of patients on semaglutide 0.5 mg and 0.4% on 1 mg versus 0% with placebo 5
• This represents a class effect of GLP-1 receptor agonists 2

Diabetic Retinopathy Complications

• Diabetic retinopathy complications occurred in 3.0% of semaglutide-treated patients versus 1.8% with placebo in cardiovascular outcome trials 1, 5
• The absolute risk increase was substantially higher among patients with pre-existing diabetic retinopathy (8.2% vs 5.2%) compared to those without known retinopathy (0.7% vs 0.4%) 5
• This may be related to rapid improvement in blood glucose control rather than a direct drug effect 1
• Patients at risk for deterioration of existing diabetic retinopathy should be carefully monitored, particularly if also treated with insulin 6

Hypoglycemia

• Hypoglycemia risk is significantly increased when semaglutide is combined with insulin, sulfonylureas, or glinides 1
• Semaglutide alone does not independently cause hypoglycemia due to its glucose-dependent mechanism 7
• Dose reduction of insulin or sulfonylureas is required when initiating semaglutide 1, 5

Acute Kidney Injury

• Risk of acute kidney injury can result from severe vomiting and dehydration 4
• Monitor renal function when initiating or escalating doses, especially in patients with pre-existing renal impairment 8
• Monitor eGFR in patients reporting severe gastrointestinal reactions 8

Cardiovascular Effects

• Heart rate increases by 2-3 beats per minute on average 5
• Pooled analysis showed a 38% higher risk of serious adverse events with semaglutide versus placebo (95% CI, 1.10-1.73) 2
• Examples of serious adverse events included acute myocardial infarction, though cardiovascular death was actually reduced 2

Contraindications (Absolute)

Semaglutide is absolutely contraindicated in the following situations: 1, 5

• Personal or family history of medullary thyroid carcinoma (MTC) - based on rodent studies showing thyroid C-cell tumors 5
• Multiple Endocrine Neoplasia syndrome type 2 (MEN2) 1, 5
• Pregnancy and breastfeeding 1
• Known hypersensitivity to semaglutide or product components 5

Important Cautions and Monitoring

Gastroparesis and Gastric Surgery

• Not recommended in patients with clinically meaningful gastroparesis 1
• Exercise caution in patients with prior gastric surgery, including bariatric surgery 1
• The delayed gastric emptying effect is usually transient with longer-acting GLP-1 receptor agonists 1

Thyroid Monitoring

• Counsel patients about symptoms of thyroid tumors: neck mass, dysphagia, dyspnea, persistent hoarseness 5
• Routine serum calcitonin monitoring is of uncertain value and may lead to unnecessary procedures 5
• If serum calcitonin is measured and significantly elevated (>50 ng/L), further evaluation is warranted 5

Other Adverse Effects

• Weight loss (intended effect but monitor for excessive loss) 1
• Injection site reactions (subcutaneous formulation) 1
• Headache, weakness, dizziness 1
• Fatigue, dysgeusia 5
• Increases in amylase (13%) and lipase (22%) from baseline 5
• Suicidal ideation (rare but reported) 2

Anesthetic Considerations

• Risk of pulmonary aspiration or residual gastric content during anesthesia due to delayed gastric emptying 9
• Pre-operative guidelines may need modification for patients using semaglutide 9

Nutritional Deficiencies

• Vitamin D deficiency occurs in 7.5% at 6 months and 13.6% at 12 months 10
• Iron depletion is frequent, with 26-30% lower ferritin levels compared to other medications 10
• More than 60% of users consume below requirements for calcium and iron 10
• Vitamin D intake averages only 20% of recommendations 10
• Targeted nutritional assessment and individualized laboratory evaluation are appropriate for at-risk patients 10

Body Composition Changes

• Total fat mass decreases by 14% at 7 months and 18% at 12 months 11
• Lean mass initially declines (-3 kg at 7 months) but stabilizes thereafter 11
• Handgrip strength improves significantly (+4.5 kg at 12 months) 11
• Prevalence of sarcopenic obesity decreases from 49% to 33% at 12 months 11

Drug Interactions

• Semaglutide delays gastric emptying and may impact absorption of oral medications 5
• Clinical pharmacology trials showed no clinically relevant effects on absorption of most oral medications 5
• Exercise caution when oral medications are administered concomitantly 5

Immunogenicity

• Approximately 1% of patients develop anti-semaglutide antibodies 5
• Of these, 0.6% develop antibodies cross-reacting with native GLP-1 5
• Clinical significance of neutralizing activity is uncertain 5

Route-Specific Considerations

Subcutaneous versus oral semaglutide show similar adverse effect profiles, though gastrointestinal disorders are slightly more common with oral formulation (30.19% vs 27.76%) 3. Serious outcomes constitute 3.07% for oral and 2.25% for subcutaneous formulations 3.

1, 4, 1, 2, 5