Written by: Ryan Clark, Health & Wellness Writer
Medically Reviewed by: Dr. Sarah Mitchell, MBBS, MRCGP — General Practitioner
Last Updated: February 2026 | Fact-Checked ✓
Wegovy side effects are the most common concern for anyone starting semaglutide weight loss treatment. Wegovy (semaglutide) has become a leading treatment for weight management in the UK, offering significant results for many individuals. Like its counterpart Ozempic, which is used for type 2 diabetes, Wegovy works by mimicking a gut hormone that targets areas of the brain involved in appetite regulation. While highly effective, it is important for users to be aware of the potential side effects and understand how to manage them.
Table of Contents
Most side effects of Wegovy are gastrointestinal in nature, are typically mild to moderate, and tend to decrease over time as the body adjusts to the medication. This guide provides a comprehensive overview of the common, less common, and serious side effects associated with Wegovy, along with practical tips for managing them effectively.
Common Side Effects of Wegovy
The vast majority of side effects occur during the initial titration phase, when the dose is gradually increased. According to clinical trials and real-world data from providers like Boots Online Doctor, the most frequently reported side effects include:
- Nausea: This is the most common side effect, often described as a feeling of sickness or an upset stomach.
- Diarrhoea: Loose, watery stools can occur, particularly after starting the medication or increasing the dose.
- Constipation: Some users experience the opposite effect, with difficulty passing stools.
- Vomiting: This is less common than nausea but can occur, especially at higher doses.
- Abdominal Pain: General discomfort, cramping, or pain in the stomach area.
- Headache: A common side effect of many medications, including Wegovy.
- Fatigue: Feeling unusually tired or lacking in energy is often reported in the first few weeks.
A study published in the New England Journal of Medicine found that gastrointestinal events were the most common adverse effects, but they were typically transient and mild-to-moderate in severity. [1]
How to Manage Common Side Effects
- Eat Smaller, More Frequent Meals: Large meals can exacerbate nausea and bloating. Opt for smaller portions spread throughout the day.
- Avoid High-Fat and Greasy Foods: Fatty foods can slow stomach emptying further, worsening feelings of sickness. Choose bland, low-fat foods like crackers, toast, and rice.
- Stay Hydrated: Sip water throughout the day, especially if you are experiencing diarrhoea or vomiting, to prevent dehydration.
- Increase Fibre Intake for Constipation: If you are constipated, gradually increase your intake of high-fibre foods like fruits, vegetables, and whole grains.
- Dose Titration: Adhere strictly to the prescribed dose escalation schedule. Increasing the dose too quickly is the primary cause of severe side effects.
- Dizziness: Feeling lightheaded, particularly when standing up.
- Bloating and Gas (Flatulence): An increase in gas and a feeling of fullness in the abdomen.
- Gastroesophageal Reflux Disease (GERD): Heartburn or acid reflux can be triggered or worsened.
- Injection Site Reactions: Redness, swelling, or itching at the site of injection.
- Pancreatitis: Inflammation of the pancreas. Symptoms include severe, persistent pain in the abdomen that may radiate to your back, with or without vomiting. If you experience this, seek urgent medical care.
- Gallstones (Cholelithiasis): Wegovy can increase the risk of developing gallstones. Symptoms include sudden and severe pain in the upper right abdomen, fever, and jaundice (yellowing of the skin and eyes).
- Allergic Reactions: As with any drug, severe allergic reactions (anaphylaxis) are possible. Symptoms include swelling of the face, lips, tongue, or throat; problems breathing or swallowing; severe rash or itching; fainting or feeling dizzy; and a very rapid heartbeat.
- Risk of Thyroid C-Cell Tumors: In studies with rodents, semaglutide caused thyroid C-cell tumors. It is not known whether Wegovy causes such tumors in humans. Therefore, you should not use Wegovy if you or any of your family have ever had a type of thyroid cancer called medullary thyroid carcinoma (MTC) or if you have an endocrine system condition called Multiple Endocrine Neoplasia syndrome type 2 (MEN 2). [2]
Less Common Side Effects
Some patients may experience other side effects that are less frequent but still noteworthy:
Serious but Rare Side Effects
While rare, there are serious side effects associated with Wegovy that require immediate medical attention. It is crucial to be aware of the warning signs.
Frequently Asked Questions (FAQ)
1. Do Wegovy side effects go away?
For most people, the common gastrointestinal side effects are most prominent during the first few weeks and as the dose is increased. They typically lessen or resolve completely as the body adapts to the medication.
2. Are the side effects of Wegovy the same as Ozempic?
Yes, because both medications contain the same active ingredient (semaglutide), their side effect profiles are virtually identical. The experience of side effects depends more on the individual and the dosage than on the brand name.
3. Can I stop taking Wegovy if the side effects are too much?
You should always speak to your doctor or prescriber before stopping any medication. They may be able to suggest ways to manage the side effects or recommend staying on a lower dose for a longer period before attempting to titrate up again.
Medical Disclaimer: This article is for informational purposes only and does not constitute medical advice. Semaglutide (Wegovy, Ozempic) is a prescription medication that should only be used under the supervision of a qualified healthcare professional. Always consult your GP or specialist before starting, stopping, or changing any medication. Individual results may vary.