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What are the side effects of Wegovy?

Author : Adeel Arshad MPharm PIP, Pharmacist Independent Prescriber at PrivateDoc (8th April 2023)

Wegovy is a new weight loss medication that is poised to enter the weight loss market in the UK at some stage in 2023.

The drug has been heralded as a “game changer” for weight loss, but like all medications patients should be mindful of the risk of side effects when taking Wegovy.

What is Wegovy?

Wegovy is a once weekly injection designed to aid patients losing weight by helping them feel fuller for longer and curbing appetite, which results in the consumption of less calories.

The active ingredient of Wegovy is semaglutide which works by slowing the movement of food through the stomach resulting in a decrease in appetite and in turn causing weight loss.

Patients will experience weight loss as a result of reduced calorie intake and increased exercise creating a calorie deficit.

It is likely that most patients will experience some mild side effects with Wegovy, whilst some patients may experience no side effects at all. For some patients side effects may be severe, hence it is important for patients to understand Wegovy's side effect profile and to keep a close eye on their general wellness as they commence treatment and throughout the Wegovy programme.

It is important to note that everyone is different and patients should not judge the experiences and results of others as an indication of their experience or results.

Classification of Side Effects

All licensed medications are provided with thorough information on the potential side effects. At PrivateDoc we ensure that all of our treatment pages have a clear indication of side effects and we make this information available during our consultation process and again via email at dispense (if a prescription is written), in addition to the physical PIL information provided with all medications.

Side effects are generally classified as follows

  • Very common: Around 1 in 10 people
  • Common: Around 1 in 100 people and 1 in 10 people
  • Uncommon: Around 1 in 1000 people and 1 in 100 people
  • Rare: Around 1 in 10000 and 1 in 1000 people

What are the common potential side effects from Wegovy weight loss injections?

In 2021 the clinical trial data for Wegovy was published and in this trial 1306 patients were given the medication with a group of 655 patients given a placebo over the course of 68 weeks. 94% of the participants completed the trial of Wegovy.

The most common side effects experienced from taking Wegovy weekly injections are headache, constipation, diarrhoea, stomach pain, nausea, vomiting. Patients also reported feeling tired or week which may be a consequence of reduced calorie intake in addition to the action of the drug on the body and any side effects. These are classified as very common side effects which means that more than one patient in every 10 treated will experience these side effects.

Wegovy side effects

The severity of side effects will vary between patients and patients should expect these side effects to ease with time as they adjust to the medication. Constipation was found to last longer than the other digestive side effects, but it was found to be mostly mild.

The titration of Wegovy is designed to manage the occurrence and severity of side effects when using Wegovy weight loss injections and it is for this reason that patients increase the dose taken every 4 weeks over a period of 16 weeks when starting Wegovy treatment.

How to manage your side effects when using Wegovy weight loss injections

The most important thing to do when in the first 16 weeks of Wegovy treatment is to keep a close eye on any side effects that you are experiencing through the use of the medication.

Nausea is a common side effect when using Wegovy, but with time this should ease. Self help techniques to manage nausea when using Wegovy include:

  • Get plenty of fresh air and avoid hot stuffy spaces if you are feeling sick
  • Eat plain foods that are low fat but nutritious
  • Drink ambient water and make sure you are hydrated
  • Eat slowly, reduce portion sizes and potentially eat more often to create a balance between portion size and frequency of meals

Constipation is a Wegovy side effect that may become a nuisance. It is important to ensure that you are well hydrated to ensure the normal movements of the bowls and to eat high-fibre foods to encourage the bowls to move as normal. PrivateDoc can help with advice on constipation at any time during your Wegovy treatment programme.

Whilst constipation may be experienced, diarrhoea is also a side effect that may occur when using Wegovy. In the case of diarrhoea this should be managed in the same way as diarrhoea that may be experienced as a matter of course. The priority should be to stay hydrated and consider the use of Oral rehydration salts (ORS) which are a mixture of electrolytes (salts) and carbohydrates (in the form of sugar) dissolved in water. They are used to replace salts and water that are lost when you have diarrhoea.

Headache and Dizziness are also side effects of Wegovy weekly injections. Patients should manage headaches with over the counter pain relief in the first instance and headaches should ease with time. If headaches are persistent, qualified clinical support should be sought from your Wegovy prescriber. PrivateDoc offers a managed treatment plan that caters for advising patients on all side effects experienced. For dizziness patients should contact a clinician if they are concerned or worried that they may come to harm from this side effect. Patients should ensure they advise all medications that are being used for blood pressure when taking Wegovy.

Rare and Uncommon Side Effects of Wegovy

1% of patients may experience an inflamed pancreas (acute pancreatitis) as a side effect of using Wegovy weight loss injections. Pancreatitis results in sudden and severe pain in the centre of the stomach accompanied by nausea or vomiting, diarrhoea and a high temperature. If you notice any of these acute symptoms you should report this to your prescriber but also seek immediate medical help through your normal local routes. This is classified as an uncommon side effect of Wegovy.

0.1% of patients may experience an allergic reaction to Wegovy and this may take the form of swelling of the face, mouth and throat, difficulty breathing, a rapid resting heartbeat and feeling faint. These symptoms are classified as uncommon and immediate medical attention should be sought.

There are only two rare side effects of Wegovy and the incidence rate of these side effects makes them very unlikely to occur for patients, however they must be documented and patients should be made aware of the risks of these rare side effects. The first is Anaphylaxis which is a severe, potentially life-threatening allergic reaction that can develop rapidly. Immediate medical attention must be sought without delay. The second rare side effect is Angioedema and this will present as a part of the body suddenly becoming very swollen accompanied by a raised, itchy rash (hives) if an allergic reaction has caused the swelling.


Wegovy is a clinically proven and licensed weight loss treatment, administered as a weekly injection. As a licensed medication it is likely that patients may experience some side effects and these have been classified using the normal side effect classifications for medication.

Patients that are embarking on weight loss treatment with Wegovy are wise to monitor their side effects and ensure that they work with a weight loss provider like PrivateDoc that offers a comprehensive weight loss treatment plan with follow up consultations and side effect monitoring and support.

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Did you know?

Over 40% of the population has tried to lose weight at some point in the last 5 years – so you're certainly not alone