Like all medications, GLP-1 agonists can cause side effects. Most are mild and transient, but it's important to know about them. Here we review what the research shows.
Common Side Effects (>10% of patients)
Nausea is most common and occurs in approximately 20-40% initially. Other common symptoms are constipation, diarrhea, vomiting, and abdominal pain. These usually decrease after 4-8 weeks.
Less Common Side Effects (1-10%)
Headache, dizziness, fatigue, dyspepsia, and flatulence. Injection site reactions occur but are rarely serious.
Rare but Serious Side Effects (<1%)
Pancreatitis (inflammation of the pancreas) is rare but requires immediate medical attention if severe abdominal pain occurs. Gallstone problems can occur with rapid weight loss. These are actively monitored in clinical studies.
Contact healthcare immediately if
Severe abdominal pain radiating to the back, persistent vomiting, or vision changes. Call 1177 or 112.
How we reduce side effect risk
- Slow dose escalation over several weeks
- Smaller meals and avoiding fatty food
- Good fluid intake
- Regular follow-up with doctor
Frequently asked questions
How long does the nausea last?
For most people, nausea decreases significantly within 4-8 weeks as the body adjusts.
Can I stop if side effects are too severe?
Yes, treatment can always be stopped or the dose adjusted. Discuss with your doctor.
When should I seek urgent care?
If you have severe abdominal pain radiating to the back, persistent vomiting, or vision changes. Call 1177 for advice or 112 in an emergency.
Can I take medication for nausea?
Yes, in some cases the doctor prescribes antiemetics during escalation. Do not self-medicate without checking first.
Does GLP-1 increase gallstone risk?
Rapid weight loss can increase gallstone risk. We monitor symptoms and can adjust pace or diet advice to reduce the risk.