The weight loss medication Wegovy (semaglutide) has emerged as a significant advancement in weight management, offering a new option for patients seeking effective, long-term results.
When used alongside a reduced-calorie diet and increased physical activity, Wegovy has been shown to help patients lose up to 15% of their body weight within 1 year on the 2.4mg dose[1]. However, like any medication, Wegovy may cause side effects. Understanding the nature of these side effects is important for anyone considering weight loss injections, or currently using Wegovy to help support proactive management of any adverse reactions.
This article provides a detailed overview of the known side effects of Wegovy, from common gastrointestinal symptoms to less frequent but more serious side effects. This guide covers the side effects after taking the medication - to find out how to safely administer Wegovy, see our helpful guide on How to Take Wegovy® Injections.
What are the side effects of Wegovy?
Like many prescription medications, Wegovy injectable pens may cause side effects, particularly during the early stages of use or when the dose is increased. The most commonly reported side effects include gastrointestinal symptoms such as:
- Nausea
- Vomiting
- Diarrhoea
- Constipation
Others may experience:
- Headache
- Tiredness
- Dizziness
- Indigestion
- Bloating
- Heartburn
These effects are usually mild and tend to subside over time as your body adjusts to the treatment.
Very common side effects of Wegovy
These may affect more than 1 in 10 people
When first starting Wegovy or when the dosage is increased, a range of gastrointestinal side effects is very common.
Gastrointestinal side effects are common due to Wegovy’s mechanism of action, which slows down the emptying of the stomach, helping you feel fuller for longer. The official Wegovy patient information leaflet classifies these side effects as very common:
- Nausea: Often reported as the most frequent side effect of Wegovy, nausea can range from mild to moderate. It is most common when you first start the medication and as your dose is increased.
- Vomiting: Using Wegovy can sometimes cause vomiting, particularly in the initial stages of treatment. If vomiting is severe or persistent, it's important to contact a healthcare professional as it can lead to dehydration.
- Diarrhoea: Increased bowel movement frequency and looser stools are also commonly reported by individuals using Wegovy. Diarrhoea treatments are recommended if you experience loose and watery stools. It is important to be aware that diarrhoea or vomiting can lead to dehydration, which may be serious. Make sure to stay hydrated during your treatment and contact your GP or doctor if you experience these symptoms.
- Constipation: Some individuals may experience difficulty with bowel movements. It's a common gastrointestinal complaint alongside other side effects like nausea and diarrhoea. Constipation treatments are effective in helping with bowel movement difficulties.
- Stomach pain: General discomfort in the stomach area, including pain, a sense of fullness or bloating, and increased gas, are frequent complaints.
- Headache and fatigue: Some people report a sense of tiredness or fatigue. These side effects are commonly experienced as the body adjusts to the medication.
For most people, these side effects are temporary and tend to subside over time as the body adjusts to Wegovy.
Common side effects of Wegovy
These may affect up to 1 in 10 people
Some patients may experience common side effects while taking Wegovy. Many of these common side effects are gastrointestinal and tend to be experienced as the body adjusts to the medication.
- Dizziness: Some people report feeling light-headed or dizzy, particularly when taking the first dose of Wegovy. Staying well-hydrated and avoiding sudden movements may help reduce these effects.
- Upset stomach or indigestion: Also referred to as dyspepsia, this includes general stomach discomfort, burning or a feeling of fullness during or after meals.
- Burping: Increased burping may occur due to Wegovy’s effect on the digestive system.
- Flatulence: Some individuals report excess gas or bloating, which can cause discomfort.
- Bloating: A feeling of fullness or swelling in the stomach area can accompany other gastrointestinal side effects.
- Gastritis (stomach inflammation): Wegovy may cause irritation or inflammation of the stomach lining. Symptoms can include stomach pain, nausea, or vomiting. If these become severe or persistent, seek medical attention.
- Reflux or heartburn (gastro-oesophageal reflux disease or GORD): Some patients may experience a burning sensation in the chest or throat caused by stomach acid moving up into the oesophagus.
- Gallstones: Gallstones may develop in some individuals, especially those experiencing rapid weight loss. Signs include upper abdominal pain, nausea or vomiting.
- Hair loss: Temporary hair thinning or loss has been reported by some individuals while using Wegovy. This is typically mild and may be linked to the rapid weight change experienced by the body. You can consider hair loss treatments if you think you are experiencing hair thinning.
- Injection site reactions: Redness, swelling or irritation at the injection site may occur. These symptoms are usually mild and resolve on their own.
- Changes in taste: Some people notice a change in how food or drink tastes, which may affect appetite or food preferences.
- Changes in skin sensation: Tingling, numbness or unusual skin sensations have been reported in some cases.
- Low blood sugar (hypoglycaemia) in patients with diabetes: In people with diabetes, Wegovy can increase the risk of low blood sugar, especially if used with other glucose-lowering medications. Monitoring blood sugar levels regularly is important.
Many of these side effects are manageable and often reduce in severity over time. However, patients should speak to a healthcare professional if symptoms persist or cause concern.
Uncommon side effects of Wegovy
These may affect up to 1 in 100 people
Some side effects of Wegovy are less common but may still occur in a small proportion of patients.
- Fast heartbeat: An increased heart rate has been reported in some individuals. If you experience a consistently rapid heartbeat or palpitations, seek immediate medical attention.
- Increased pancreatic enzymes: Wegovy may raise levels of pancreatic enzymes such as lipase and amylase, which can be seen in blood tests. This typically does not cause noticeable symptoms but may be monitored by your doctor.
- Delayed stomach emptying: Wegovy works by slowing down how quickly food leaves the stomach. In some cases, this delay may become more pronounced, potentially causing prolonged fullness or discomfort.
- Low blood sugar (hypoglycaemia) in patients without diabetes: Although more common in people with diabetes, low blood sugar can also occur in those without the condition. Symptoms of low blood sugar include shakiness, sweating, dizziness or confusion.
- Increased bilirubin levels: In rare cases, Wegovy may affect liver function, leading to a rise in bilirubin levels. This may cause yellowing of the skin or the whites of the eyes (jaundice). If this occurs, seek medical attention.
While these side effects are uncommon, it’s important to be aware of them and to contact a healthcare professional if you have any concerns during treatment.
Serious side effects experienced using Wegovy
The serious side effects of Wegovy require immediate medical attention. It is important to be aware of the symptoms associated with these conditions so that you can seek urgent medical attention should you experience them.
Common serious Wegovy side effects that may affect up to 1 in 10 people:
- Diabetic eye disease (diabetic retinopathy): If you have diabetes, Wegovy may increase the risk of complications related to diabetic eye disease. Let your doctor know if you experience any changes in vision during treatment.
Uncommon serious Wegovy side effects that may affect up to 1 in 100 people:
- Inflamed pancreas (acute pancreatitis): If you have severe pain in your stomach area (abdomen) that will not go away, with or without vomiting, stop using Wegovy and contact your doctor right away. You may feel the pain from your abdomen to your back.
- Kidney or bladder stones: Symptoms may include pain in the lower abdomen or back, discomfort during urination or changes in the colour of your urine. Speak to your doctor if these symptoms occur.
Rare, serious Wegovy side effects that may affect up to 1 in 1,000 people:
- Severe allergic reactions (anaphylaxis): Seek immediate medical attention if you experience any of the following symptoms: difficulty breathing, swelling of the face, lips, tongue or throat, difficulty swallowing, wheezing, rapid heartbeat, pale or cold skin, dizziness or feeling faint.
- Hip fractures: There is a small risk of an increased likelihood of hip fractures associated with taking Wegovy. This is not because Wegovy directly weakens bones, but because rapid weight loss can sometimes lower bone density and make bones more fragile.
To help keep your bones healthy while losing weight, eat a balanced diet with enough calcium and vitamin D, do weight-bearing exercise if you can, and speak to your doctor if you have concerns about bone health.
Taking a Vitamin D3 and K2 supplement can help to support healthy bones and maintain bone strength.
Not known (frequency not known from the available data):
- Bowel obstruction: This is a more severe form of constipation and may include symptoms such as abdominal pain, bloating, or vomiting. Contact a healthcare professional if you suspect bowel obstruction.
Wegovy is classified as a black triangle medicine in the UK, which means it is under enhanced safety monitoring. As a newly approved treatment, all side effects should be reported to your doctor, even those not listed in the patient information leaflet. This allows healthcare authorities to identify any new or rare side effects that may appear over time.
Wegovy long-term side effects
The long-term safety profile of Wegovy is still being reviewed. While many of the common side effects are short-term, some of the more serious risks, such as pancreatitis and gallbladder problems, can have long-term implications.
The need for ongoing monitoring and communication with a doctor is essential for anyone using Wegovy for an extended period.
Managing Wegovy side effects
Many of the common side effects of Wegovy can be managed with simple, proactive strategies. The following tips are recommended to help minimise discomfort:
- Eating smaller, more frequent meals to avoid overburdening the stomach.
- Avoid high-fat, greasy, or very spicy foods that can trigger nausea.
- Staying well-hydrated by drinking plenty of water, especially if experiencing diarrhoea or vomiting.
- Eating slowly and paying attention to your body's fullness cues.
- Talking to a doctor about over-the-counter remedies that may be appropriate for managing nausea, constipation, or diarrhoea.
Wegovy frequently asked questions
Is Wegovy safe?
Yes, Wegovy is a safe and clinically proven injectable weight loss medication. It is authorised for use in the UK by the Medicines and Healthcare products Regulatory Agency (MHRA) and has undergone extensive clinical trials to confirm its effectiveness and safety[3]. To help you administer Wegovy safely, we have also prepared a guide to Important Information About Injectable Weight Loss Treatments, featuring a helpful video tutorial.
Like all medicines, Wegovy can cause side effects, though serious reactions are rare. If you have any health concerns or pre-existing conditions, always consult your healthcare professional before starting Wegovy.
Is Wegovy an appetite suppressant?
Yes, Wegovy works as an appetite suppressant. Its active ingredient, semaglutide, affects areas of the brain responsible for controlling hunger and feeling full. By curbing appetite, Wegovy helps patients eat less and lose weight more effectively.
How can I reduce the side effects of Wegovy?
To help reduce the side effects of Wegovy, you can try adjusting your eating habits. Eat slowly and stop eating as soon as you feel full. It’s also wise to limit or avoid fatty, fried, or heavily spiced foods, which can aggravate nausea or digestive upset.
Does Wegovy cause hair loss?
Hair loss can occur while taking Wegovy and is listed as a known side effect. This is more likely in people who experience rapid weight loss, so the loss of hair may be more closely related to losing weight quickly rather than the medication itself.
Is dehydration a side effect of Wegovy?
Dehydration can occur indirectly while using Wegovy, especially if side effects like vomiting or diarrhoea lead to fluid loss. Staying hydrated with water, herbal teas, or clear broths can help replenish fluids and maintain electrolyte balance.
Do people regain weight after stopping Wegovy?
Yes, weight regain is common after people stop using Wegovy. When the medication is stopped, the appetite levels may return to previous levels. To prevent weight gain after discontinuing Wegovy, follow a balanced diet, stay active and adopt long-term healthy lifestyle habits..
Can I drink alcohol while taking Wegovy?
Drinking alcohol while taking Wegovy is not recommended, as it can increase side effects like nausea, dizziness and dehydration. Alcohol may also affect your appetite and slow weight loss. If you do decide to drink alcohol whilst using Wegovy, do so in moderation, avoid drinking on an empty stomach and stay hydrated.
Do the side effects of Wegovy go away?
Yes, most side effects of Wegovy are temporary and tend to improve as your body adjusts to the medication. Common side effects like nausea, dizziness or upset stomach usually subside within a few weeks.
If side effects persist or become severe, speak to your doctor or GP, who may suggest ways to manage them or adjust your treatment.
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