Like all medications, Wegovy and Mounjaro may cause side effects.
The most common side effects are gastrointestinal. These include nausea, heartburn, bloating, constipation (occasionally accompanied by abdominal cramps), diarrhoea and vomiting . This is because one of the ways Wegovy and Mounjaro help is by slowing down how fast the stomach and intestine empty, which contributes to a sense of early and prolonged fullness after meals. During our clinical consultations we will provide you with advice of how to reduce the risk of the common gastrointestinal side effects and how to manage them if they occur.
Another common side effect includes headache but usually settles within a few days. To help with headaches drink plenty of clear fluids, eat small amounts, get enough sleep and rest and take a simple pain medication such as paracetamol to help control the pain as your body gets used to Wegovy or Mounjaro.
Side effects are typically worse when first starting the treatment and for the first few days after moving up to a higher dose pen.
Usually if the medication dose is increased slowly, most people (>95%) find side effects fairly easy to tolerate, particularly as they tend to improve over time.
During our follow up clinical consultations we will assess your response to the medication and any side effects and we will advise when to increase the medication dose to reduce the side effects.
Other side effects seen with these medications include:
Gallstones: In clinical trials, around 1-3 in 100 people using Wegovy or Mounjaro developed gallstones. This may be due to rapid weight loss.
Cholecystitis: is an inflamed gallbladder and up to 1 in 100 people taking Wegovy and Mounjaro get this. If you develop abdominal pain, especially on the right side under your ribs you must seek medical attention.
Pancreatitis: this is a condition where the pancreas becomes inflamed. If you develop severe abdominal pain with or without persistent vomiting this may be a sign of pancreatitis and you need to get medical help immediately.
Gastroparesis: this is unusually slow emptying of the stomach that can be associated with excess vomiting. It has been noted in a very small number of patients taking Wegovy and Mounjaro.
Anaphylaxis: this is a severe allergic reaction. If you experience symptoms like difficulty in breathing, swelling of the face, lips or tongue or difficulty swallowing you may be having a severe allergic reaction (anaphylaxis) and you need to seek immediate medical help.
If you get any side effects please let us know. This includes any possible side effects not listed in the Patient Information leaflet.
You can also report side effects directly via the Yellow Card Scheme or search for MHRA Yellow Card.
Please make sure to read the Patient Information Leaflet carefully before starting any treatment