Common Side Effects
What are the most common side effects of GLP-1 Agonists?
Starting a GLP-1 medication, like Wegovy or Mounjaro, can be a powerful step toward weight loss and better blood sugar control. However, around 30–40% of users experience side effects — most of them temporary and manageable 【Davies et al., 2017】. Understanding what to expect helps reduce anxiety and makes the journey easier.
How GLP-1 Medications Work
- Stimulate insulin secretion when blood sugar is high, lowering diabetes risk
- Reduce glucagon release, keeping blood sugar stable
- Slow digestion, preventing blood sugar spikes and increasing fullness
- Curb appetite by acting on brain centres that regulate hunger 【Drucker, 2017】
Most Common Side Effects
Gastrointestinal (GI) Symptoms (most frequent):
- Nausea & Vomiting: Up to 50% of users, especially at treatment start
- Diarrhoea or Constipation: Can cause dehydration if severe
- Abdominal pain & bloating: Linked to slowed digestion 【Davies et al., 2017】
Other Reported Symptoms:
- Fatigue and headaches
- Dizziness (often linked to dehydration)
- Changes in taste perception
- Rare: Pancreatitis or severe allergic reactions 【Elashoff et al., 2011; FDA, 2023】
Tips for Managing Side Effects
- Start low, go slow: Begin at a small dose, increasing gradually to reduce GI upset 【NICE, 2023】
- Stay hydrated: Fluids help with nausea and diarrhoea
- Eat smaller, more frequent meals: Prevents nausea and bloating 【Davies et al., 2017】
- Monitor symptoms: Contact your doctor if side effects are persistent, severe, or worsening
When to Seek Medical Advice
- Ongoing or severe nausea, vomiting, or diarrhoea
- Sudden, severe abdominal pain (possible pancreatitis)
- Allergic reactions (swelling, difficulty breathing)
- Concerns about medication safety 【MHRA, 2023】
References
- Elsevier Health. GLP-1 receptor agonists. Retrieved from Elsevier Health
- Drucker, D. J. (2017). Mechanisms of action and therapeutic application of glucagon-like peptide-1. JCI, 127(10), 4032-4043.
- Davies, M. et al. (2017). Managing the gastrointestinal side effects of GLP-1 receptor agonists. Diabetes, Obesity and Metabolism, 19(6), 762–772.
- Elashoff, M. et al. (2011). Pancreatitis with GLP-1 use. Diabetes Care, 34(6), 1234-1239.
FDA (2023). FDA alerts on dosing errors with compounded semaglutide products.
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