Weight Loss
Wegovy Side Effects and How to Manage Them
In one sentence: The most common Wegovy side effects are gut-related, such as feeling sick, diarrhoea, being sick and constipation, and they are usually mild, do not last long and are most likely when your dose goes up, but severe or lasting stomach pain needs urgent medical attention.
At a glance
Most common: nausea (feeling sick), diarrhoea, vomiting (being sick) and constipation.
Usually short-lived: most effects are mild to moderate and settle as your body adjusts.
Worst at dose increases: side effects are most likely in the weeks after your dose goes up.
Easing them: smaller, plainer meals, eating slowly and drinking enough fluids all help.
Serious but less common: pancreatitis and gallbladder problems. Severe, lasting stomach pain needs urgent help.
Alcohol can add to nausea and works against your goals, so keep within the UK low-risk limit of 14 units a week.
Side effects are the most common reason people hesitate about Wegovy, so it helps to know what is normal, what you can do about it, and what needs medical attention. This guide covers the common gut-related effects, when they tend to happen, how to ease them, the serious warning signs, and advice on low blood sugar and alcohol. It builds on the reason side effects come and go, which is the step-up dose schedule in our Wegovy dosage guide.
"Nausea is by far the most common issue, and the good news is that it usually eases as your body settles, especially between dose increases. The people who cope best tend to eat smaller, plainer meals and stop eating when they feel full, rather than pushing through. If side effects are severe or not settling, tell us, because the dose plan can be adjusted."
Key takeaways
What are the most common Wegovy side effects?
Feeling sick (nausea), diarrhoea, being sick (vomiting) and constipation. Headache and tiredness are also common.
When are Wegovy side effects worst?
Usually in the weeks after a dose increase. Most are mild to moderate and ease as your body adjusts.
How do you reduce nausea on Wegovy?
Eat smaller, plainer meals, eat slowly, avoid greasy or very rich food, and sip fluids throughout the day.
What are the warning signs to act on?
Severe or lasting stomach pain (possible pancreatitis), signs of a serious allergic reaction, or heavy vomiting and diarrhoea causing dehydration.
What are the common side effects of Wegovy?
The most common Wegovy side effects are gut-related and were seen often in clinical trials. According to the Wegovy Summary of Product Characteristics, the very common effects (affecting more than 1 in 10 people) at the 2.4 mg dose were nausea, diarrhoea, vomiting and constipation.1
Side effect | How often (at 2.4 mg) |
Nausea (feeling sick) | Very common, about 44 in 100 |
Diarrhoea | Very common, about 30 in 100 |
Vomiting (being sick) | Very common, about 25 in 100 |
Constipation | Very common, about 24 in 100 |
Headache and tiredness | Very common |
Dizziness, tummy pain, indigestion, burping, bloating, gallstones, hair loss, injection-site reactions | Common (up to 1 in 10) |
These figures come from trials, so your own experience may be milder. Many people get one or two of these effects rather than all of them.
When do Wegovy side effects start and how long do they last?
Side effects tend to appear soon after you start and after each dose increase, then settle. The Wegovy Summary of Product Characteristics notes that most gastrointestinal reactions were "mild to moderate in severity and of short duration" and were "most frequently reported during dose escalation".1 In practice, this means the first few weeks and each step up in dose are when you are most likely to notice them, and they usually ease within days as your body adjusts. If a side effect does not settle, your prescriber can slow down your dose increases.
How can you manage Wegovy side effects?
Most gut-related side effects can be eased with simple changes to how and what you eat.
Easing nausea
Eat smaller meals more often, rather than large ones.
Choose plainer, blander foods and avoid greasy, fried or very rich meals.
Eat slowly and stop when you feel full.
Sip water or cold drinks through the day, and try ginger or peppermint if they help you.
Easing constipation
Increase fibre gradually with vegetables, fruit and wholegrains.
Drink plenty of fluids and stay active where you can.
Ask your pharmacist about a suitable fibre supplement or gentle laxative if needed.
Easing diarrhoea
Drink extra fluids to replace what you lose and avoid getting dehydrated.
Ease back on very fatty or spicy foods until it settles.
Speak to your pharmacist if it is frequent or persistent.
What are the serious side effects of Wegovy to look out for?
Serious side effects are much less common, but it is important to recognise them. The Wegovy Summary of Product Characteristics lists warnings including acute pancreatitis, gallbladder problems, dehydration affecting the kidneys, and rare serious allergic reactions.1
Seek urgent medical help if you have:
Severe, lasting stomach pain that may spread to your back, with or without vomiting. This can be a sign of pancreatitis.
Pain in the upper right side of your tummy, fever, or yellowing of the skin or eyes, which can point to gallbladder problems.
Signs of a serious allergic reaction, such as swelling of the face, lips or throat, a widespread rash, or difficulty breathing. Call 999.
Signs of dehydration from heavy vomiting or diarrhoea, such as feeling very thirsty, dizzy or passing little urine.
Wegovy and low blood sugar (hypoglycaemia)
On its own, Wegovy rarely causes low blood sugar. As Diabetes UK explains, "when taken on its own, Wegovy does not often cause blood sugar levels to become too low", but "hypos are more common when you take this drug with other diabetes medications such as insulin or a sulphonylurea".2 If you take insulin or a sulphonylurea, your prescriber may lower the dose of those medicines when you start Wegovy. Learn the signs of a hypo, such as shakiness, sweating and confusion, and how to treat it, if this applies to you.
Can you drink alcohol on Wegovy?
There is no absolute ban on alcohol with Wegovy, but there are good reasons to be careful. Alcohol can add to nausea and stomach upset, it adds calories that work against your weight goals, and it can increase the risk of low blood sugar if you also take insulin or a sulfonylurea. If you do drink, stay within the UK low-risk guidance. The NHS advises not regularly drinking more than 14 units a week, spread over three or more days.3
Injection-site reactions
Mild redness, a small bruise or a little soreness where you inject is common and usually settles quickly. Rotating your injection spot each week helps reduce this, as we explain in Wegovy injection sites. Tell your pharmacist if a site becomes a persistent hard lump or the reaction spreads.
When should you get medical advice?
Contact your prescriber or pharmacist if side effects are severe, do not settle, or are stopping you from eating and drinking normally. Seek urgent help (call 111, or 999 for an emergency) for the warning signs above, especially severe stomach pain or a serious allergic reaction. If side effects are making treatment hard to continue, do not simply stop: read what happens when you stop Wegovy and speak to your prescriber first.
"Feeling a bit sick in the first week or after a dose rise is expected and usually manageable. What is not routine is severe, unrelenting stomach pain, being unable to keep fluids down, or any sign of an allergic reaction. Those need prompt medical attention, not a wait-and-see approach."
Frequently asked questions
What are the most common side effects of Wegovy?
The most common side effects are gut-related: feeling sick (nausea), diarrhoea, being sick (vomiting) and constipation. Headache and tiredness are also common. Most are mild to moderate and ease as your body adjusts to the medicine.
How long do Wegovy side effects last?
Most side effects are short-lived and settle within days, especially between dose increases. They are most likely in the first few weeks and after each dose step-up, and tend to improve as your body gets used to the medicine.
How do you stop feeling sick on Wegovy?
Eat smaller, plainer meals, eat slowly and stop when full, avoid greasy or very rich food, and sip fluids through the day. Nausea usually eases with time. If it is severe or stopping you from eating and drinking, speak to your prescriber, as your dose plan can be adjusted.
What are the serious side effects of Wegovy?
Serious but less common effects include pancreatitis and gallbladder problems. Seek urgent medical help for severe, lasting stomach pain that may spread to the back, pain in the upper right tummy with fever or yellowing skin, signs of a serious allergic reaction, or dehydration from heavy vomiting or diarrhoea.
Can you drink alcohol while taking Wegovy?
There is no absolute ban, but alcohol can worsen nausea, add calories and can increase the risk of low blood sugar if you also take insulin or a sulfonylurea. If you drink, stay within the UK low-risk guidance of no more than 14 units a week, spread over several days.
Does Wegovy cause low blood sugar?
On its own, Wegovy rarely causes low blood sugar. The risk is higher if you also take insulin or a sulfonylurea for diabetes, in which case your prescriber may reduce the dose of those medicines when you start Wegovy.
Related Wegovy guides
Sources and references
Wegovy FlexTouch Summary of Product Characteristics (SmPC), emc. Section 4.8 side-effect frequencies (nausea, diarrhoea, vomiting and constipation very common; the note that gastrointestinal reactions are mostly mild to moderate and occur during dose escalation) and section 4.4 warnings (pancreatitis, gallbladder disease, dehydration and kidney function, hypoglycaemia, allergic reactions).
Diabetes UK. Wegovy (semaglutide). Low blood sugar is uncommon with Wegovy alone but more likely with insulin or a sulfonylurea.
NHS. Calculating alcohol units. UK low-risk guidance of no more than 14 units a week, spread over three or more days.
Medical disclaimer: This article is for general information and does not replace advice from a qualified healthcare professional. Wegovy is a prescription-only medicine. If you experience severe or worrying symptoms, seek medical help promptly. Always read the patient information leaflet and speak to your clinician or pharmacist about your individual circumstances.
Our commitment to accuracy: This page was written using current UK sources, including the electronic medicines compendium (emc), Diabetes UK and the NHS, and is reviewed by our Superintendent Pharmacist. We review our weight-management content regularly and update it as guidance changes.
About the author
Blog author
Dayna Sheppard
Dayna is a pharmacy manager with over 15 years of pharmacy experience. She is focused on delivering a safe and excellent pharmacy service for patients.
Medically reviewed by
Medical reviewer
Taslima Hussain
Taslima is a pharmacist who is passionate about patient care. She has experience working in community pharmacy as a locum.
