Most side effects of these medications are unpleasant rather than dangerous. A small number are not. This page covers the symptoms that mean stop reading and get help, and the ones that mean call your prescriber the same day rather than waiting for your next appointment.
Call emergency services or go to an emergency department now
- Severe abdominal pain, especially constant and radiating through to your back, with or without vomiting
- Difficulty breathing, or swelling of the face, lips, tongue or throat, or widespread hives. This can progress rapidly
- Chest pain or pressure, particularly with breathlessness, sweating, or pain spreading to the arm, jaw or neck
- Sudden vision changes, including loss of vision in one eye
- Signs of stroke: face drooping, arm weakness, slurred or difficult speech
- Vomiting blood, or material resembling coffee grounds, or black tarry stools
- Confusion, unusual drowsiness, or being difficult to rouse
- Fainting, or a seizure
- Severe low blood sugar: confusion, shaking and sweating that does not improve after eating, particularly if you take insulin or a sulfonylurea
Tell them you take a GLP-1 medication and name it. It changes what they look for and is easily missed if you do not say it.
Contact your prescriber the same day
- Vomiting or diarrhea you cannot stop, or inability to keep fluids down
- Passing very little urine, or urine that is very dark
- Persistent pain in the upper right abdomen, especially after eating, or spreading to your right shoulder blade
- Yellowing of the skin or eyes, dark urine with pale stools
- Vomiting food eaten many hours earlier, or recognisable undigested food
- A lump or swelling in your neck, persistent hoarseness, or difficulty swallowing
- Palpitations that persist, or a heartbeat that feels irregular
- New or worsening thoughts of harming yourself
- Any symptom that arrives suddenly on a dose you have been stable on for weeks
For how this fits alongside the other effects of these medications, see GLP-1 Side Effects: The Complete Management Guide.
The rule that covers what is not on this list
No page can list everything. Two patterns are worth carrying instead.
Direction of travel. Effects that appear after a dose increase and then ease are behaving as expected. Anything that keeps escalating, or that arrives out of nowhere on a stable dose, is not.
Severity out of proportion. Queasiness, fullness and mild discomfort are ordinary. Pain that is severe, or that you would describe as unlike anything you have had before, is not ordinary, whatever its location.
If you are not sure
Being unsure is itself a reason to get assessed. The cost of an unnecessary trip is a few hours. The cost of waiting out something serious is considerably higher, and the conditions on this page are ones where time matters.
Nobody at an emergency department will think you wasted their time for coming in with severe abdominal pain.
Should you stop taking it
If you are having emergency symptoms, do not take another dose before you have been assessed, and tell the clinician what you are on.
Whether to stop permanently is a decision for your prescriber, not one to make alone in either direction. Do not stop out of caution without telling them, and do not restart because you feel better.
Reduce the odds of getting here
Tell your prescriber about your full history before starting, particularly any previous pancreatitis, gallstones, thyroid cancer in you or your family, significant kidney problems, or diabetic eye disease.
Report symptoms early rather than at the point they become severe. Keep fluids up during any episode of vomiting or diarrhea. And do not adjust doses yourself.
Two of these deserve their own reading before you need them: pancreatitis warning signs and gallbladder symptoms. For anything involving sedation, tell the anaesthesia team you take a GLP-1.
Frequently asked questions
How do I tell ordinary nausea from something serious?
Severe or escalating pain, especially radiating to the back, is the main distinction. Ordinary effects ease across the week.
What if symptoms settle before I am seen?
Still report it. Episodes that resolve often recur, and knowing about the first changes what happens next.
Do I need to stop before an operation?
Tell your surgical and anaesthesia teams that you take it. Whether to pause is their decision, and it matters for anaesthesia safety.
Are these effects common?
The emergency ones are uncommon. They are listed because recognising them matters, not because they are likely.
Who should I call first?
For anything in the red block, emergency services. For the amber block, your prescriber the same day.
What if I cannot reach my prescriber?
Use an urgent care service or nurse line rather than waiting days. Do not sit on symptoms because a practice is closed.