Wegovy Pill Side Effects: Symptoms and How to Manage Them

What side effects does the Wegovy pill cause?

The Wegovy pill joined the landscape of weight loss treatments as the novel oral form of semaglutide, a GLP-1 receptor agonist used for weight management alongside diet and physical activity. 

Wegovy pill side effects are most often digestive, including nausea, vomiting, diarrhoea, constipation and stomach pain. Headache and fatigue are also very common. Gastrointestinal Wegovy pill side effects are usually mild to moderate and are reported most often while the dose is being increased; many improve as your body adjusts. [1, 2]

Although most side effects are manageable, uncommon or rare problems can need prompt medical attention, including pancreatitis, anaphylaxis and serious vision changes associated with a very rare eye condition called NAION. [2, 3, 4]

The effects of the Wegovy pill range from common digestive symptoms to uncommon and rare reactions. The digestive system is affected most often because the Wegovy pill works through GLP-1 pathways that alter appetite and gastrointestinal function. This is why digestive symptoms are the ones most often reported. [2] Not everyone taking the Wegovy pill will experience side effects, and the type and severity of side effects vary between people.

Most common side effects

The most common side effects are:

• nausea
• vomiting
• diarrhoea
• constipation
• indigestion and abdominal pain
• headache and fatigue

In the OASIS 4 clinical trial, nausea affected 46.6% of people taking Wegovy tablets, vomiting 30.9%, diarrhoea 17.6% and constipation 20.1%.[2, 5]

Among the effects users commonly report, gastrointestinal symptoms are the most frequent. These common side effects and other Wegovy pill side effects tend to be most noticeable during the dose escalation period and are usually mild to moderate. Nausea, vomiting and diarrhoea were generally of short duration, although constipation tended to last longer. [2]

Hair loss and gallstones are each classed as a common side effect. In OASIS 4, hair loss occurred in 6.4% of people taking Wegovy tablets compared with 2.0% taking placebo and was reported more often in people who achieved greater weight loss; gallstones occurred in 2.5% compared with 1.0%. [2]

Other common effects include dizziness, burping, gas, bloating, gastritis, reflux or heartburn, changes in taste and changes in skin sensations. In OASIS 4, skin sensations such as sensitive skin, tingling, burning or pain from normally non-painful touch were reported in 4.9% of people taking Wegovy tablets. [2]

An upset stomach does not necessarily mean the treatment is unsafe or that it is not working. For many people, the body adjusts over time. However, repeated vomiting or diarrhoea can cause dehydration, so it is important to stay hydrated. [2, 6]

Uncommon side effects

Uncommon Wegovy pill side effects listed in the UK product information include:

• increased heart rate
• low blood pressure
• delayed gastric emptying
• kidney or bladder stones
• low blood sugar in people without type 2 diabetes

Kidney or bladder stones are listed as an uncommon serious effect in the patient information. Possible symptoms can include pain in the back or lower abdomen, difficulty urinating or changes in urine colour. [2]

Low blood sugar is also a common side effect in people with type 2 diabetes. There is an increased risk of low blood sugar levels when semaglutide is used with certain diabetes medications, particularly insulin or a sulfonylurea. [2]

Acute pancreatitis is uncommon but serious and is covered below.

Serious side effects

Serious side effects are much less common, but it is important to recognise them. Acute pancreatitis can cause persistent severe stomach pain or severe abdominal pain, sometimes spreading to the back, with or without vomiting. The Medicines and Healthcare products Regulatory Agency strengthened warnings in 2026 after rare reports of severe acute pancreatitis, including a severe form involving tissue death and fatal cases. [3]

For people with type 2 diabetes, worsening diabetic retinopathy is another important risk. Rapid improvement in blood sugar control may temporarily worsen existing diabetic eye disease. If you have diabetic retinopathy and notice changes in vision while taking the Wegovy pill, contact your doctor. [2]

Bowel obstruction has also been reported, although its frequency is not known. Severe constipation accompanied by abdominal pain, bloating or vomiting needs medical assessment. [2]

Rare serious allergic reactions can cause swelling of the face or throat and difficulty breathing. Sudden, painless vision loss, often affecting one eye, or rapidly worsening eyesight also needs urgent assessment because semaglutide has been very rarely associated with non-arteritic anterior ischaemic optic neuropathy, or NAION. [4]

Wegovy does not affect just one organ. Most side effects involve the gut, while less common or serious problems can involve the pancreas, gallbladder, kidneys and eyes. [2, 3, 4]

How do Wegovy pill side effects compare to the injection?

   

There is no clear evidence that the pill has fewer side effects overall. Wegovy pill side effects vs injection are broadly similar because both forms contain semaglutide. The current UK SmPC states that the safety profile of the Wegovy pill form in OASIS 4 was consistent with the injection trials, although some individual effects differed in frequency. [2]

Where the pill causes more side effects

Some gastrointestinal effects were reported more frequently with the pill in separate clinical trials. Nausea occurred in 46.6% with Wegovy tablets compared with 43.9% across the 2.4 mg Wegovy injection programme, while vomiting occurred in 30.9% versus 24.5%. Dyspepsia also had a higher frequency category with the pill. [2]

Hair loss was reported in 6.4% with the tablets in OASIS 4 compared with 2.5% with the 2.4 mg injection programme. These side effects figures come from separate studies rather than a direct head-to-head comparison, and side effects can vary between individuals, so they should not be interpreted as proof that the pill causes more side effects overall. [2]

Where the injection causes more side effects

Diarrhoea and constipation were reported more often in the injection programme: diarrhoea in 29.7% and constipation in 24.2%, compared with 17.6% and 20.1% respectively with the tablets. [2]

The Wegovy injection can cause injection site reactions, which do not occur with the tablet. Injection site reactions are a common side effect of the injection. [7] If you are choosing between formulations, our Wegovy pill vs injection guide explains the wider practical differences, including use of the Wegovy pen.

How long do Wegovy pill side effects last?

How long Wegovy pill side effects last depends on the symptom. Nausea, vomiting and diarrhoea are generally short in duration, while constipation can last longer. [2] There is also no single exact time after taking a tablet when symptoms must begin.

When do Wegovy pill side effects start? Gastrointestinal Wegovy pill side effects are most often reported during dose escalation, particularly in the first few weeks after starting Wegovy treatment or after dose increases. [2, 6]

If you are wondering “how long do side effects of Wegovy last?”, the answer varies. The effects of the Wegovy pill do not follow one fixed timetable. General weight-loss medicine advice from Guy's and St Thomas' NHS Foundation Trust says nausea and vomiting often settle within around three to four weeks after starting treatment or increasing the dose as the body adjusts. [8]

Do side effects get worse when you increase your dose?

They can. Dose increases are designed to be gradual because gastrointestinal side effects are most frequently reported during the dose escalation period. [2] Symptoms may recur before the maintenance dose is reached.

Some people notice nausea, diarrhoea or discomfort again after dose increases before the body adjusts to the new dose. The symptoms noticed after a dose increase are usually gastrointestinal ones.

Do not change your dose yourself to manage Wegovy pill side effects. If symptoms are persistent or difficult to tolerate, speak to the prescriber before the next dose increase or before progressing towards the maintenance dose. It is worth knowing that reaching the highest dose is not a goal in itself: a prescriber can hold you at a lower dose for longer, or settle at one you tolerate well, if the response is adequate.

Does the Wegovy pill have long-term side effects?

Long-term oral-specific evidence is still developing. The pivotal OASIS 4 trial involved 64 weeks of treatment followed by seven weeks off treatment, while wider semaglutide safety information also comes from longer and larger injection studies. [2, 5] Known Wegovy pill side effects can persist or occur later in treatment, so ongoing monitoring still matters.

Constipation can last longer than nausea or vomiting. Gallstones may occur during treatment, and rapid weight loss itself can increase the risk of gallstone formation. [2, 9] Hair shedding can also appear after marked or rapid weight loss. Telogen effluvium occurs when more hair follicles enter the resting and shedding phase after a major physical change, and marked weight loss is a recognised trigger. [10]

In OASIS 4, average body weight fell by 13.6% at week 64, while 47.0% of participants taking oral semaglutide achieved at least 15% weight loss. [2, 5] Hair loss was reported more frequently in people who achieved greater weight loss. People can lose weight at different rates, so these results cannot predict an individual's response.

Current UK safety reviews have not found evidence of a causal link between GLP-1 medicines and suicidal thoughts, self-injury or depression. [11]

How to manage Wegovy pill side effects

   

Many Wegovy pill side effects can become easier to manage as the body adjusts. Smaller meals, careful food choices and good hydration may help with digestive symptoms, while persistent or severe effects should be discussed with a healthcare professional. [6, 8]

Nausea and vomiting: common side effect advice

To manage nausea, eat smaller, more frequent meals and choose bland foods when symptoms are worse. If fatty or spicy foods make nausea, indigestion or stomach pain worse, reduce or avoid them temporarily. General NHS digestive advice notes that fatty foods can contribute to digestive discomfort and heartburn, while spicy foods can trigger heartburn or diarrhoea in some people. Fatty or spicy foods do not affect everyone in the same way. [8, 12]

Stay hydrated by drinking fluids regularly, especially if you have been vomiting. The Wegovy pill must still be taken on an empty stomach after at least an eight-hour fast, with up to 120 mL of water, followed by at least 30 minutes before food, drink or other oral medicines. [2]

If vomiting is frequent, you cannot keep fluids down, or you feel lightheaded, contact your healthcare team because dehydration can lead to kidney problems. [6, 8]

Diarrhoea and constipation

For diarrhoea, stay hydrated and try smaller, frequent meals. Fluids are important because ongoing diarrhoea can cause dehydration and kidney problems. If symptoms are severe, bloody or persistent, seek medical advice rather than relying only on over the counter medicines. [6, 8]

To manage constipation, stay hydrated, increase fibre gradually and stay physically active if you are able. If you are considering an over the counter laxative, ask a pharmacist which option is appropriate, particularly if you take other medications.

Headaches and fatigue

Headaches and fatigue are very common Wegovy pill side effects and may be more noticeable during dose increases. [2] To manage headaches, stay hydrated, avoid skipping meals and rest when needed. Smaller, frequent meals may help if reduced appetite is making it difficult to eat regularly. [8]

If a headache is severe, new, persistent or accompanied by vision changes, seek medical advice rather than assuming it is a common Wegovy pill side effect.

How safe is the Wegovy pill for people trying to lose weight?

Is the Wegovy pill safe? For adults who meet the licensed criteria and are appropriately assessed, the Wegovy pill has been authorised by the MHRA after evaluation of its quality, safety and effectiveness. [1] That does not mean the Wegovy pill is free of risk or suitable for everyone.

The safety data from OASIS 4, published in the New England Journal of Medicine, showed that gastrointestinal adverse events were common; the Wegovy tablets SmPC reports that 3.4% of people taking semaglutide tablets permanently stopped treatment because of gastrointestinal events. [2, 5]

Serious adverse events were reported in 3.9% of participants taking oral semaglutide 25 mg in OASIS 4, compared with 8.8% taking placebo. [5] These are serious adverse events recorded during the clinical trial and should not be interpreted as proof that every event was caused by the medicine.

Clinical trials and post-marketing monitoring continue to inform the safety profile and other side effects. For suitable patients, the potential health benefits of clinically appropriate weight loss and weight management need to be considered alongside the known side effects and individual medical history.

If you are considering Wegovy or other weight loss treatments, a clinical assessment is important before you start treatment. Other options, including Mounjaro online, may be considered depending on individual suitability.

Drug interactions and contraindications

The main formal contraindication in the current UK Wegovy tablets SmPC is hypersensitivity to semaglutide or any of the tablet ingredients. [2] The current UK Wegovy tablet SmPC does not carry a boxed warning for thyroid tumours and does not list thyroid cancer or a personal or family history of medullary thyroid carcinoma as a contraindication. [2] A European regulatory review concluded that available evidence did not support a causal association between GLP-1 receptor agonists and thyroid cancer. [13]

Semaglutide can delay stomach emptying and may influence absorption of other oral medicines. Levothyroxine exposure can increase, and people taking warfarin or other coumarin anticoagulants may need closer INR monitoring when they start treatment. [2]

Blood sugar also matters. Taking the Wegovy pill with insulin or certain diabetes medications, especially sulfonylureas, can increase the risk of low blood sugar. A clinician may need to review your diabetes treatment to reduce the risk of hypoglycaemia. [2] One point worth clarifying, as it often causes confusion with the dual GIP/GLP-1 medicines: semaglutide has not been found to reduce the effectiveness of the contraceptive pill, so no extra contraceptive precautions are needed on that account – though the pill should still be taken after the 30-minute waiting window.

Tell the prescriber about all other medications, supplements and relevant medical conditions before taking Wegovy. The Wegovy pill should not be used as a substitute for insulin in diabetes, and it is not recommended in severe gastroparesis. [2] 

Because semaglutide slows gastric emptying, the stomach may still contain food after the usual pre-operative fasting, and stomach contents being inhaled into the lungs during general anaesthesia or deep sedation has been reported with this class of medicine. Tell the surgical team and the anaesthetist about the treatment before any planned operation, endoscopy or procedure involving sedation.

When to contact a doctor

Contact a doctor or your prescribing service if Wegovy pill side effects are persistent, worsening or interfering with normal eating and drinking. Seek prompt advice if you are vomiting repeatedly, cannot keep fluids down, have signs of dehydration, or develop ongoing abdominal discomfort. [6, 8]

Seek immediate medical attention for persistent severe stomach pain or severe abdominal pain that may spread to the back, particularly with vomiting, because this can indicate pancreatitis. [2, 3] Difficulty breathing, swelling of the face or throat or other signs of an allergic reaction are also a medical emergency.

Severe constipation with abdominal pain, bloating or vomiting can be a sign of bowel obstruction and needs urgent medical assessment. [2] Pain in the upper right side of the abdomen, particularly with fever or yellowing of the skin or eyes, can indicate a gallbladder problem and also needs prompt assessment. [2] If you have diabetes and existing diabetic retinopathy, new vision changes also need prompt medical advice. [2]

Sudden vision loss or rapidly worsening eyesight requires urgent eye assessment because of the very rare risk of NAION. [4] If you have symptoms of low blood sugar such as sweating, shaking, weakness or confusion, follow the advice provided by your diabetes team and seek urgent help if symptoms are severe. [2, 6]

FAQS

These answers cover some of the questions people most often ask about Wegovy pill side effects.

What are the worst side effects of Wegovy?

The serious side effects that may require urgent treatment include acute pancreatitis, serious allergic reactions, bowel obstruction and severe vision changes linked to NAION. Diabetic retinopathy complications, kidney or bladder stones and severe dehydration can also require medical treatment. [2, 3, 4, 6]

Most people do not experience these serious side effects, but knowing the warning signs helps distinguish them from expected digestive symptoms.

How long after taking Wegovy pills do side effects start?

There is no fixed number of hours after taking the Wegovy pill when side effects start. Gastrointestinal symptoms are most often reported during dose escalation, so side effects may become noticeable after starting treatment or following dose increases. [2]

For many people, the body adjusts, and symptoms lessen over time. If they remain troublesome or worsen, contact the prescriber.

Can you drink alcohol while taking the Wegovy pill?

The UK Wegovy tablet SmPC does not list a specific interaction with alcohol. However, NHS advice says it is best not to drink alcohol while taking semaglutide because it can worsen nausea or vomiting. [2, 14]

Alcohol also adds calories, which may work against weight loss goals. If you have diabetes, pancreatitis risk factors or another condition affected by alcohol, ask your clinician for individual advice.

Do Wegovy pill side effects go away on their own?

Many do. The most common side effects involving the digestive system are usually mild to moderate and often improve as the body adjusts, although constipation can last longer. [2]

Do the side effects of Wegovy go away for everyone? Not necessarily. Persistent, severe or unusual effects Wegovy pill users experience should be assessed rather than simply waited out. These effects of the Wegovy pill may need a treatment review.

Is the Wegovy pill safe during pregnancy?

No. The Wegovy pill should not be used during pregnancy. Semaglutide should be stopped at least two months before a planned pregnancy because it remains in the body for a long time. [2]

If pregnancy occurs while taking the Wegovy pill, contact the prescriber. Wegovy tablets should also not be used while breastfeeding because a risk to the breastfed child cannot be excluded. [2]

Does the Wegovy pill cause hair loss?

Yes, hair loss can occur and is classed as a common side effect. [2] It was reported more often in people who achieved greater weight loss.

The relationship may not be solely a direct drug effect. Marked weight loss is independently recognised as a trigger for telogen effluvium, a temporary shift of hair follicles into the shedding phase. [2, 10] If hair loss is substantial or continues, speak to a healthcare professional so other causes can be considered.