Guide · Side effects · 3 min read
When to see a doctor
The common digestive side effects mostly come when you start and when the dose goes up, and they ease over time. 1·2 Some signs, though, need help without waiting. 1·2·3
Get emergency help now
- A serious allergic reaction: trouble breathing, fast swelling of the face, lips, tongue or throat, a very fast heartbeat, dizziness or fainting. 1·2·3
- Vomit with blood, vomit that looks like coffee grounds, or green vomit. 6
- Dehydration together with blue, grey or pale lips or skin, trouble breathing, confusion or being hard to wake. 7
Contact a doctor right away
- Severe stomach pain that does not go away. It may spread to your back, with or without nausea or vomiting. It can be a sign of an inflamed pancreas. 1·2·3
- Sudden loss of vision or eyesight that gets worse quickly. The Wegovy leaflet lists this as a very rare optic nerve problem (NAION). 1·4
- Severe constipation with stomach ache, bloating and vomiting. The leaflet lists this as bowel obstruction among serious side effects. 1
- Nausea, vomiting or diarrhea that does not go away, not keeping fluids down, dizziness on standing that does not pass, or peeing much less than usual. 3·6·7
Tell your doctor
- Signs of gallbladder problems: pain in your upper stomach, fever, yellowing of the skin or eyes, clay-colored stools. 3
- Your heart racing or pounding for several minutes. 3
- A lump or swelling in your neck, hoarseness, trouble swallowing or shortness of breath. The US Medication Guide lists these as possible signs of a thyroid tumor. 3
- If you have diabetes: changes in vision, or signs of low blood sugar such as cold sweats, shakiness, a fast heartbeat, hunger and dizziness. Low blood sugar is more likely with a sulfonylurea or insulin. 1·3
- Any side effect that bothers you or does not go away. 4·5
Tell them ahead
- Before surgery or a procedure under anaesthesia, say that you use this medicine. 1·2·3
- If you are planning a pregnancy, talk to your doctor: semaglutide should be stopped at least 2 months before, tirzepatide at least 4 weeks before. 3·4·5
- Don't stop your medicine without talking to your doctor. 1·4
In CalJab
The symptoms you log in How are you, your doses and your weight appear together in your doctor report. Add the questions you want to ask as questions in the report, so you don't forget them at the appointment.
In an emergency, call the emergency number of the country you are in.
Sources
- 1Wegovy product information and package leaflet. European Medicines Agency (EMA). Accessed 20 October 2026. ema.europa.eu
- 2Mounjaro product information and package leaflet. European Medicines Agency (EMA). Accessed 20 October 2026. ema.europa.eu
- 3Wegovy US prescribing information and Medication Guide. Novo Nordisk, FDA approved. Accessed 20 October 2026. novo-pi.com
- 4NHS: Semaglutide. Last reviewed 15 May 2026. nhs.uk
- 5NHS: Tirzepatide. Last reviewed 15 May 2026. nhs.uk
- 6NHS: Diarrhoea and vomiting. Last reviewed 21 December 2023. nhs.uk
- 7NHS: Dehydration. Last reviewed 1 May 2026. nhs.uk
Written by the CalJab team, with sources. It does not replace your doctor's advice. Found a mistake? Write to support@caljab.app.