Wegovy tablets and the Wegovy injection share the same active ingredient. But they don't affect your body in quite the same way, and their side effects reflect that.
The tablet's strict fasting rule, daily dosing schedule and different way of being absorbed all shape how people tolerate it. So it's worth understanding on its own.
This guide focuses on the tablet. It draws on data from the OASIS 4 phase 3 trial to explain which side effects oral semaglutide causes, how often they happen and what you can do to reduce them. For a full overview of the treatment, see our complete guide to Wegovy semaglutide tablets.
Most side effects are digestive, mild to moderate, and strongest while your dose is going up. For most people, they ease with time.
Why oral semaglutide causes side effects
Semaglutide is a GLP-1 receptor agonist. It mimics a natural hormone called glucagon-like peptide-1, which your gut releases after eating.
This hormone helps regulate your appetite, slows how quickly food leaves your stomach (gastric emptying) and tells your brain you're full.
Those effects are what make semaglutide work for weight management. But they're also the main reason for its most common side effects. When food moves through your digestive system more slowly than usual, nausea, bloating and changes in your bowel habits are a predictable result.
Side effects don't mean something's gone wrong. It's usually the medicine doing what it's meant to.
The tablet also needs specific conditions to be absorbed. You take it on an empty stomach with no more than 120ml of plain water, then have nothing else for at least 30 minutes. That routine helps the tablet absorb properly, and some people find it adds to digestive discomfort in the early weeks.
How do the side effects of oral semaglutide differ from the injection?
The tablet and the injection contain the same active ingredient, and their side effect profiles are broadly similar.
In OASIS 4, 74% of people on the tablet reported a digestive side effect of some kind.1 That's in line with the STEP 1 trial of the injection, where around three quarters of people taking semaglutide reported digestive side effects too.2
The types of side effects are the same: nausea, vomiting, diarrhoea, constipation and tummy discomfort. In both forms, they tend to be worst while your dose is going up, and improve over time.
For the injection's side effects, see our Wegovy injection side effects article.
What are the most common side effects of oral semaglutide?
The most frequently reported side effects of oral semaglutide are digestive. Nausea was the single most common one in the OASIS 4 trial:1
- Nausea - the most common side effect, reported by 46.6% of people taking oral semaglutide, compared with 18.6% on placebo
- Vomiting - reported by 30.9% of people, compared with 5.9% on placebo
- Diarrhoea - one of the more frequently reported effects
- Constipation - also common, and it can last longer than other digestive effects
- Stomach pain - including discomfort in the upper and lower tummy
The US prescribing information for the tablet notes that the types and frequencies of side effects are similar to those seen with semaglutide 2.4mg injections.3
How common are gastrointestinal side effects?
In OASIS 4, digestive side effects of any kind were reported by 74% of people taking oral semaglutide, compared with 42% on placebo.1 That's clearly higher than placebo.
Stopping treatment because of side effects was uncommon, happening in around 7% of people on oral semaglutide. Serious side effects were actually less common in the semaglutide group than in the placebo group (3.9% compared with 8.8%).4
Most side effects were mild to moderate, and they settled as the dose increases went on.
Side effects are most likely while your dose is being increased, which happens gradually over 12 weeks before you reach the maintenance dose. That's deliberate. It gives your body time to adjust and lowers the risk of severe digestive symptoms.
How to manage nausea and other digestive symptoms
Most digestive side effects can be managed with a few practical changes. These steps are in line with advice from prescribing clinicians and pharmacists:
- Eat smaller, more frequent meals - rather than two or three big ones. Large meals sit in your stomach for longer when it's emptying more slowly, which makes nausea worse.
- Avoid high-fat and processed foods - especially in the early weeks. Fat slows your stomach down even more and is a common trigger for nausea on semaglutide.
- Eat slowly and stop when you feel full - semaglutide makes you feel full sooner than usual. Eating past that point makes nausea much more likely.
- Drink plenty of fluids - especially if you're vomiting or have diarrhoea. Losing a lot of fluid this way can, rarely, affect your kidneys.
- Don't lie down straight after eating - staying upright for an hour or two after a meal helps reduce reflux and nausea.
- Take the tablet correctly - on an empty stomach with plain water only. Taking it with food or other drinks reduces how much is absorbed.
Be careful with alcohol during treatment. It can make nausea worse, and because semaglutide slows how quickly your stomach empties,5 alcohol may affect you differently from usual. There's no absolute ban, but keeping it low, especially while your dose is going up, is sensible.
Symptoms severe, or not settling after a few weeks? Speak to your prescribing clinician. Sometimes the dose increases can be paused at a lower dose to give you more time to adjust, rather than stopping treatment.
Smaller meals, slower eating and stopping when you're full go a long way to keeping nausea in check.
Less common side effects
Beyond the main digestive symptoms, semaglutide is linked to a few other effects that happen less often:
- Headache and tiredness - reported by roughly one in ten people, likely linked to eating less in the early weeks
- Dizziness - especially when standing up quickly; drinking enough fluids helps
- Faster heart rate - semaglutide trials have reported an average increase of one to four beats a minute, with bigger increases in a small number of people
- Gallbladder problems - losing a lot of weight can raise your risk of gallstones, and gallbladder problems have been reported in a small proportion of people in semaglutide trials. Any ongoing pain in the upper right of your tummy should be checked promptly.
These are usually manageable, but tell your clinician if they persist or get worse.
Serious but rare side effects
Semaglutide's overall safety record is well established. But there are a few rare, serious side effects to be aware of.
Pancreatitis
In January 2026, the MHRA updated the product information for all GLP-1 receptor agonists, including semaglutide, to strengthen warnings about severe acute pancreatitis (inflammation of the pancreas). This followed reports of rare cases of severe and fatal pancreatitis.
Between 2007 and October 2025, the MHRA received 1,296 Yellow Card reports of pancreatitis linked to GLP-1 receptor agonists, across an estimated 25.4 million packs dispensed.6 That's a very small absolute risk.
Pancreatitis should be suspected if you have severe, ongoing tummy pain that spreads to your back, sometimes with nausea or vomiting. This needs urgent medical attention. If pancreatitis is confirmed, semaglutide must be stopped and should not be restarted.
Severe tummy pain that spreads to your back needs urgent medical attention. Stop taking semaglutide and get help straight away.
Vision changes: NAION
In February 2026, the MHRA issued a Drug Safety Update about non-arteritic anterior ischaemic optic neuropathy (NAION). It's a condition that can cause sudden, painless loss of vision in one eye, and it has very rarely been reported with semaglutide.7
The MHRA's assessment found it to be a very rare side effect. It had received three reports through the Yellow Card scheme, against an estimated 10.2 million packs of semaglutide dispensed in the UK up to August 2025.
Treat any sudden or rapidly worsening vision loss on semaglutide as urgent. Go to eye casualty or A&E straight away, and tell the team you're taking semaglutide, as private prescriptions may not show up on your NHS record.
Thyroid considerations
In studies on rodents, semaglutide caused thyroid tumours. It isn't known whether this applies to humans.
Because of this, the US prescribing information carries a warning for people with a personal or family history of a rare thyroid cancer (medullary thyroid carcinoma) or a condition called multiple endocrine neoplasia type 2 (MEN 2). Tell your prescriber if either applies to you. Any unexplained lump in your neck, or difficulty swallowing, should be checked by a doctor.
Do oral semaglutide side effects go away?
Yes, for most people. The digestive side effects are usually worst while your dose is going up, and tend to ease once you're on the maintenance dose.
In OASIS 4, digestive side effects were generally short-lived,1 and few people stopped treatment because of them. Managing side effects well helps you stay on treatment long enough to get the full benefit. For what to expect, see our guide to how much weight you can lose on Wegovy tablets.
The dose schedule, starting low and going up every four weeks, is specifically designed to let your body adapt. If you do have persistent or severe symptoms, your clinician can pause the increases at a lower dose for longer before continuing.
Constipation can last longer than nausea and vomiting for some people. Eating more fibre and drinking more fluids is the usual first step. If it doesn't clear up, your clinician can advise on other options.
Nutritional considerations during treatment
Eating less during semaglutide treatment can raise the risk of falling short on some nutrients, especially if your food choices are limited or your appetite is very low.
A daily multivitamin can help top up key micronutrients while you're actively losing weight, including vitamins A, C, D and the B vitamins, which can fall when you eat less overall.
This matters even more if you're also taking orlistat, which reduces how well you absorb fat-soluble vitamins. If you're switching between treatments, or taking any other weight management medicine, ask your pharmacist whether you need extra nutritional support.
For the latest on availability, visit the Wegovy tablets page.
When to seek medical advice
Contact your GP or prescribing clinician if you experience:
- Severe or persistent nausea, vomiting, or diarrhoea that does not improve after several weeks
- Severe abdominal pain, especially if it radiates to the back, with or without nausea or vomiting
- Signs of dehydration: dizziness, rapid heartbeat, reduced urination, or extreme thirst
- Persistent constipation that does not respond to dietary adjustments
- Any unexplained lump in the neck, hoarseness, or difficulty swallowing
- Rapid or significant worsening of vision in one eye
Attend eye casualty or A&E immediately for sudden vision loss. For severe abdominal pain, seek urgent medical care and do not wait for a routine appointment.
Frequently asked questions
Do the side effects of Wegovy tablets go away?
Yes, for most people. The most common side effects of oral semaglutide, particularly nausea and vomiting, are most intense during the dose escalation phase and tend to ease once the maintenance dose is reached. In the OASIS 4 trial, gastrointestinal events were generally described as mild to moderate and transient. Constipation can persist longer than other GI symptoms in some patients, but dietary adjustments usually help. If side effects are severe or not settling after several weeks, speak to your prescribing clinician, as the escalation schedule can sometimes be paused at a lower dose to allow more time for adjustment.
What are the worst side effects of Wegovy tablets?
The most troublesome side effects reported by patients are nausea and vomiting, which affect roughly 47% and 31% of people respectively on the oral tablet. These are most severe during the early weeks of treatment when the dose is being increased. Serious but rare side effects include acute pancreatitis and, very rarely, sudden vision loss (NAION). The MHRA strengthened its warnings on both of these in early 2026. Severe, persistent abdominal pain radiating to the back or any sudden change in vision should be treated as urgent and require immediate medical attention.
When do Wegovy tablet side effects start?
Side effects typically begin within the first one to two weeks of starting treatment, as the body adjusts to the medication. They tend to peak when the dose is increased and then settle over the following weeks. Because the tablet uses a gradual 12-week dose escalation schedule starting from a low dose, the severity of early side effects is usually manageable. Patients who find a particular dose increase difficult can ask their clinician to pause escalation at that dose for longer before moving up.
How long do the side effects of Wegovy tablets last?
Nausea and vomiting usually improve significantly after the first few weeks on each new dose and often resolve or become minimal once the maintenance dose is established. Based on OASIS 4 trial data, gastrointestinal events were broadly transient. Constipation can take longer to settle and may persist throughout treatment for some patients. Any side effect that is worsening rather than improving, or that is still severe after several weeks, should be discussed with a clinician.
How can I reduce the side effects of Wegovy tablets?
The most effective steps are eating smaller, more frequent meals; avoiding high-fat and processed foods, especially in the early weeks; eating slowly and stopping when full; staying well hydrated; and not lying down immediately after eating. For the oral tablet specifically, it's also important to take it correctly: on an empty stomach with no more than 120ml of plain water, waiting at least 30 minutes before eating or drinking anything else. Alcohol can worsen nausea and should be kept to a minimum during the dose escalation phase. If symptoms are severe, your clinician can pause the dose escalation rather than stopping treatment entirely.
Do Wegovy tablets have fewer side effects than Mounjaro?
The side effect profiles of Wegovy (semaglutide) and Mounjaro (tirzepatide) are broadly similar, as both are GLP-1 receptor agonists that work by slowing gastric emptying. Both are associated mainly with gastrointestinal side effects: nausea, vomiting, diarrhoea, and constipation. There are no direct head-to-head trial data comparing their tolerability in equivalent doses. Some patients find one better tolerated than the other, but this varies individually. For a comparison of the two treatments, see our guide to Mounjaro vs Orlistat.
Is oral semaglutide available in the UK?
Not yet. The oral semaglutide tablet (Wegovy 25mg once daily) was approved by the US FDA in December 2025, but Novo Nordisk's application to the MHRA is still under review as of mid-2026, with a decision expected in late 2026. Once approved, private prescribing is likely to follow before NHS availability, which will also require a separate NICE health technology assessment. Injectable Wegovy (2.4mg and 7.2mg) and Mounjaro (tirzepatide) are both currently licensed and available in the UK.
Are semaglutide tablets the same as Ozempic?
No. Ozempic is an injectable semaglutide pen licensed for type 2 diabetes, and it's not licensed for weight management in the UK and should not be used as a substitute for Wegovy. The oral semaglutide tablet for weight management is a distinct formulation at a higher dose (25mg daily), approved in the US in December 2025 and by the MHRA in the UK on 11 June 2026. Rybelsus is a separate oral semaglutide product (3mg, 7mg, and 14mg) licensed in the UK for type 2 diabetes only, not for weight loss.
References
- Wharton S, Lingvay I, Bogdanski P, et al. Oral semaglutide at a dose of 25 mg in adults with overweight or obesity. New England Journal of Medicine. 2025;393(11):1077-1087. doi:10.1056/NEJMoa2500969
- Wilding JPH, et al. Once-Weekly Semaglutide in Adults with Overweight or Obesity (STEP 1). New England Journal of Medicine. 2021;384(11):989-1002. doi:10.1056/NEJMoa2032183
- Novo Nordisk Inc. Wegovy (semaglutide) Prescribing Information. Revised 05/2026. novo-pi.com/wegovy.pdf
- Applied Clinical Trials Online. FDA Approves Oral Wegovy Following Positive Phase III OASIS 4 Trial Results. appliedclinicaltrialsonline.com
- Novo Nordisk Ltd. Rybelsus 14 mg tablets Summary of Product Characteristics. Electronic Medicines Compendium (eMC). medicines.org.uk/emc
- Medicines and Healthcare products Regulatory Agency. GLP-1 receptor agonists: strengthened warnings for pancreatitis. Drug Safety Update. January 2026. gov.uk/mhra
- Medicines and Healthcare products Regulatory Agency. Semaglutide (Wegovy, Ozempic and Rybelsus): risk of Non-arteritic Anterior Ischemic Optic Neuropathy (NAION). Drug Safety Update. 5 February 2026. gov.uk/mhra
This article is intended for informational purposes only and does not replace professional medical advice. Always read the patient information leaflet supplied with your medication and speak to a healthcare professional if you have specific concerns.