Wegovy® side effects: What to expect, and tips to help

Reviewed by Dr Bhavini Shah

Wegovy® is a new weight loss injection, which launched in the UK in 2023. It can be used by people with high BMIs (body mass index) – a measurement used to work out if you’re a healthy weight for your height.

Like with all medications, there’s a chance you might experience side effects when taking Wegovy®. So, in this article we’re going to look at the potential Wegovy® side effects, how long they might last and what you can do to manage them.   

What is Wegovy®? 

Wegovy® is a weight loss medication which:

• Is taken as a weekly, self-administered injection. You can read our guide to find out more about how to inject yourself.
• Contains the active ingredient semaglutide.
• Works by suppressing your appetite, making you feel fuller for longer and reducing cravings. 
• Can cause side effects as every person responds differently.
• Helps people lose on average 15% of their body weight.   

Dr Mitra Dutt - “Semaglutide is the active ingredient in branded weight loss medication, Wegovy. It’s used to help people with high BMIs lose weight and works by suppressing the appetite and regulating food intake.

“Semaglutide comes in the form of an injection which is injected once per week and is effective alongside a healthy, reduced-calorie diet and increased physical activity.” 

Find out more about your weight loss options.

Common side effects of Wegovy® 

There is a chance that you’ll experience some side effects if you’re prescribed Wegovy®. They're very common Wegovy® side effects affect more than 1 in 10 people. It’s worth remembering that lots of these symptoms will pass with time, as you adjust to the treatment.

The most common side effects for Wegovy® are:

Nausea

In the 68-week trial of Wegovy® around 44% of the patients on Wegovy® experienced nausea, so it’s quite likely you might experience this symptom. There are things you can do to try and ease nausea like eating small plain meals and drinking water.

Diarrhoea

Experienced by more than 1 in 10 people, this common side effect can cause you to become dehydrated. If you have diarrhoea while taking Wegovy® try and rest, drink plenty of fluids like water or squash. You could also consider mixing a rehydrating sachet with a glass of water.

If you have signs of dehydration such as dark or smelly wee speak to a pharmacist.

Vomiting

More than 1 in 10 people using Wegovy® will be sick. If you’re vomiting, try and stay hydrated by drinking water. You could try ginger or peppermint tea as well.

If you keep being sick and cannot keep fluids down or you have signs of dehydration call 111.

Constipation

Taking Wegovy® can cause constipation. In clinical trials more than 10% of participants experienced this symptom. To help ease constipation you could:

• Increase your fibre intake
• Drink plenty of water
• Eat fruits such as prunes or figs
• Stomach ache/abdominal pain 

As well as diarrhoea, vomiting and constipation you may also experience stomachache. This side effects is experienced by 1 in 10 people using weight loss injections.

Although common abdominal pain can be a sign of other conditions like gallstones or inflammation of your pancreas (pancreatitis). You might also have a fever or feel sick with acute pancreatitis. If you suddenly develop severe abdominal pain, it's important you contact your GP immediately. If this isn't possible ring 111 or attend A&E.

Headaches

You may get headaches when using Wegovy®. This was one of the most commonly reported side effect during clinical trials. Headaches may be caused by dehydration so drink plenty of fluids. You could also take over-the-counter pain relief like paracetamol.

Tiredness

Feeling tired is common when taking weight loss medication. It could be because you’re eating less calories. So, your body has less energy from food than it is used to. You could try eating little and often. 

• You may also feel tired because of other side effects such as vomiting or diarrhoea. Try to stay hydrated and rest as much as possible.

Other common side effects can include:

• Dizziness
• Gas
• Indigestion
• Acid reflux
• Inflammation of the lining of the stomach (gastritis)
• Reaction at the injection site
• Hair loss
• Some people also reported getting gallstone disease (when gallstones start giving you symptoms).

And there are some common side effects for people with type 2 diabetes which include:

• Low blood sugar levels (hypoglycaemia)
• Diabetic retinopathy – this is when high blood sugar levels damage the back of the eye  

Rare Wegovy® side effects

These side effects are, as the name suggests, very rare but you should be aware of them just in case. These can affect between 1 in 10,000 and 1 in 1000 people.

The reported rare side effects are:

• Angioedema – a swelling under the skin often caused by something you're allergic to
• Anaphylactic reaction – a severe allergic reaction which will need urgent medical attention

Other uncommon side effects which affect 1 person in every 100 include an increased heart rate. And some people experience increased levels of lipase or amylase, two enzymes used by the body to break digest certain nutrients.

If you experience any of these side effects contact your GP immediately. If this isn't possible ring 111 or call 999 or attend A&E.

Side effects commonality

• Very common means more than 1 in 10 people
• Common means between 1 in 100 people and 1 in 10 people
• Uncommon means between 1 in 1000 people and 1 in 100 people
• Rare means between 1 in 10000 and 1 in 1000 people 

Tips on managing Wegovy® side effects

If you’re struggling to adapt to treatment and finding side effects difficult, you’re not alone. Wegovy® common side effects every 1 in 10 patients taking the medication.

Lots of the side effects will pass with time, as your body gets used to the treatment. But if you have side effects concerning you, or feel like you can’t cope, it’s important to speak to your clinician. They might be able to help with advice or support on side effects and in some cases, prescribe a treatment to help.  

How long do Wegovy® side effects last? 

Depending on the side effect you’re experiencing it might last for longer than others. And this also might depend on how well your body can tolerate the treatment. 

When you’re starting on Wegovy®, the dosage will increase every four weeks for 16 weeks. Dizziness, headaches and digestive side effects (nausea, vomiting, constipation gas) tend to be worse when you’re increasing your dosage of Wegovy®. But these do tend to pass as your body adjusts to the dosage.

Who should avoid Wegovy®

For some people taking Wegovy® isn’t recommended due to side effects and other safety concerns. You shouldn't’ take Wegovy® if you:

• Are over 75
• Are pregnant or breastfeeding
• Have liver, kidney or heart failure, an eating disorder or pancreatitis
• Are taking insulin, sulphonylureas or other weight loss drugs that work in the same way as Wegovy®, e.g. Victoza.   

Dr Mitra Dutt - “Semaglutide is not suitable for everyone. It's paramount you use a safe medicated weight loss prescriber like LloydsPharmacy Online Doctor who will assess your medical history to ensure the treatment is suitable for you and will offer ongoing support and monitoring.” 

Conclusion

As with all weight loss treatments you can expect to experience some side effects while taking Wegovy®. Common side effects include nausea, vomiting and headaches. However, these can all be managed with small changes to your diet and lifestyle. Side effects are typically short lasting too as your body gets used to the medication.  

References 

https://www.medicines.org.uk/emc/product/13801/smpc 
https://www.nhs.uk/conditions/gallstones/
https://www.nhs.uk/conditions/diabetic-retinopathy/
https://www.nhs.uk/conditions/acute-pancreatitis/