Updated 4 November 2026. This article provides general information, not individual medical advice. Read the Consumer Medicine Information for your own medicine and discuss treatment decisions with your doctor or pharmacist.
GLP-1 receptor agonists are prescription medicines used for type 2 diabetes and, for some products, weight management. They mimic a hormone involved in blood sugar regulation and appetite, and slow stomach emptying. The benefits, approved uses and risks differ between medicines. Tirzepatide acts on both GIP and GLP-1 receptors. WHO overview; TGA overview.
Common digestive side effects
Nausea, vomiting, diarrhoea and constipation are common. They can be particularly troublesome when treatment begins or the dose increases. Symptoms often ease over time, but severe or persistent symptoms need medical attention. Side-effect rates depend on the particular medicine, dose and population studied; there is no single percentage that describes every GLP-1 treatment. MHRA safety advice.
Vomiting and diarrhoea can cause dehydration and may lead to kidney injury. Keep up fluid intake within any limits set by your clinician. Contact your healthcare team if symptoms persist or you cannot keep fluids down. Ask your prescriber about troublesome symptoms before the next dose increase; do not devise your own dosing schedule. Medsafe guidance on dehydration.
What the trial numbers show
One example: three placebo-controlled adult weight-management trials of weekly semaglutide 2.4 mg (Wegovy), with treatment for up to 68 weeks. Group sizes: 2,116 on semaglutide; 1,261 on placebo. These are pooled label data, not class-wide rates or a comparison with other drugs.
Scale: 0–100% of participants
Nausea differed by 28 percentage points (44% minus 16%). Participants could report several reactions; percentages must not be added. “Abdominal pain” groups several related terms.
Scale: 0–10% of participants
Discontinuation differed by 3.6 percentage points. Stopping treatment is a different outcome from experiencing a symptom. Trial rates may differ from everyday practice.
Source for both charts: Wegovy US prescribing information, section 6.1, Table 3 and accompanying text (accessed 4 November 2026). Selected outcomes only; no confidence intervals are supplied in this label table. These figures do not apply to other doses, tablets, children or other GLP-1 medicines.
Less common risks and symptoms that need attention
Severe, persistent abdominal pain: seek urgent medical attention, especially if the pain spreads to your back or comes with vomiting. This can be a sign of pancreatitis. In January 2026, the MHRA strengthened warnings about acute pancreatitis, including rare severe cases, for GLP-1 and dual GIP/GLP-1 medicines. MHRA pancreatitis update.
Sudden loss of vision, including partial loss: obtain urgent medical assessment. The TGA has issued advice about the rare optic nerve disorder NAION and GLP-1 medicines. Do not wait for a routine appointment if your vision suddenly changes. TGA vision safety update.
Other important risks include gallstone disease, serious allergic reactions and low blood sugar. Low blood sugar deserves particular attention when other diabetes medicines are involved; ask your healthcare team about your own risk and what to do if symptoms occur. For breathing difficulty, collapse or a suspected severe allergic reaction, call 000 in Australia. This is not an exhaustive list of warnings. MHRA advice on common and serious risks.
Before anaesthesia or deep sedation
Tell the anaesthetist and procedure team that you take a GLP-1 or dual GIP/GLP-1 medicine. Delayed stomach emptying can leave stomach contents present despite fasting, creating a risk of aspiration during general anaesthesia or deep sedation. The TGA added warnings about this in 2025. Follow the team’s individual instructions about fasting and medicine timing. TGA anaesthesia warning.
Questions to take to your doctor or pharmacist
Ask which benefits are expected for you, which side effects need urgent care, how your other medicines affect risk, and what to do if you are unwell or miss a dose. Use the prescribed product and dose, obtain it from an authorised pharmacy, and read its current medicine information. MHRA patient guidance.
How this article was checked
This is an educational summary of the official sources linked above, checked on 4 November 2026. It is not a systematic review or an original analysis of patient outcomes. Counting mentions of a side effect in abstracts cannot show how often patients experience it. Likewise, positive or negative wording cannot establish a medicine’s safety or balance of benefits and harms.
Editorial correction: An earlier version described a 100-paper PubMed analysis and displayed word-frequency and sentiment charts without enough source data to verify the results. Those numerical claims and charts have been removed, along with duplicated text, and replaced with linked health-authority guidance and clearly labelled clinical-trial charts.
