The overall picture: mostly gut-related, mostly mild

Semaglutide mimics a gut hormone, so it is no surprise the side effects people notice most are digestive. In OASIS 4 — the phase 3b trial that supported the tablet's approval — gastrointestinal adverse events affected about 74% of people taking oral semaglutide 25 mg, compared with about 42% on placebo, and were described as mostly mild to moderate and transient.[2]

The high figure sounds alarming until you look at what people did with it. In the same trial, the share who stopped treatment because of side effects was small and barely above placebo — about 7% on oral semaglutide against about 6% on placebo.[2] Gut symptoms were common but, for most, tolerable enough to keep going, and Novo Nordisk describes the tablet's overall safety profile as comparable to the injectable version and to earlier semaglutide studies.[1]

Key takeaway

Common does not mean severe. Gut side effects are frequent with the Wegovy pill, but in the trial they were mostly mild, mostly temporary, and rarely a reason to stop — only about 1 in 14 people discontinued because of side effects, similar to placebo.[2]

The most common side effects

The Wegovy pill's common side effects are the familiar semaglutide profile. According to Novo Nordisk, the most commonly reported include:[1]

  • Nausea — the classic GLP-1 side effect
  • Diarrhoea and constipation — the gut can react in either direction
  • Vomiting
  • Abdominal (stomach) pain
  • Indigestion or heartburn (an upset stomach)
  • Bloating and belching
  • Headache, tiredness or fatigue, and dizziness
  • Low blood sugar (hypoglycaemia)

UK pharmacy guides echo the same gut-dominated list and note that these effects tend to be worst while the dose is being increased.[4]

An honest gap in the data

Precise per-symptom percentages — an exact figure for how many people get nausea, say — are published for the Wegovy injection but not for the 25 mg pill in the sources we can access. So we do not repeat the injection's figures as if they were the tablet's; for exact frequencies you would need the official product information, and a prescriber or pharmacist can talk you through it.

Why side effects peak during dose escalation

No one new to semaglutide starts on the full 25 mg dose — the one reported exception is people already established on the 2.4 mg once-weekly Wegovy injection, who can be transitioned directly to the 25 mg once-daily tablet by their prescriber.[3] For everyone else, the UK dose ladder climbs in steps — 1.5 mg, then 4 mg, 9 mg and 25 mg, with a minimum of one month at each level before moving up.[3] That slow climb exists for exactly this reason: according to UK pharmacy guidance, the gradual escalation is there to reduce gastrointestinal side effects, which are at their worst during dose escalation.[4]

Practically, that means the toughest stretch for most people is the escalation phase itself rather than the time spent settled on a stable dose.[4] If side effects are hard to manage, the pace is set by the prescriber, who can hold a dose for longer or step back down. Our Wegovy pill dosage page sets out the full titration ladder and how the increases are decided.

Serious risks to know about

Beyond the gut symptoms, semaglutide has less common but more serious risks. A UK pharmacy guide to the Wegovy pill flags the following to watch for and report; a single consumer-facing secondary source — not the official product information — underpins several of these points, so we present them as reported cautions rather than settled frequencies.[4]

When to seek urgent help

Severe, persistent stomach pain can be a sign of acute pancreatitis (inflammation of the pancreas) and needs urgent medical attention, according to UK pharmacy guidance.[4] Do not wait for a routine appointment if this happens.

Pancreatitis

Acute pancreatitis is reported as a risk with semaglutide medicines; the warning sign is severe, persistent abdominal pain, and UK pharmacy guidance advises seeking urgent care if it occurs.[4]

Gallbladder problems

Gallbladder disease is among the reported warnings for the Wegovy pill. UK pharmacy guidance says to report new upper-abdominal pain or jaundice (yellowing of the skin or eyes).[4]

Dehydration and kidney injury

Because vomiting and diarrhoea can cause fluid loss, there is a reported risk of acute kidney injury from dehydration. UK pharmacy guidance is simple: keep your fluids up, especially if you are unwell with gut symptoms.[4]

Low blood sugar (hypoglycaemia)

The risk of hypoglycaemia is increased when semaglutide is combined with insulin or a sulphonylurea (a type of diabetes tablet), according to UK pharmacy guidance.[4] This is one of the reasons a prescriber needs a full picture of your other medicines before starting.

Diabetic eye disease (retinopathy)

In people with diabetes, a rapid improvement in blood glucose can transiently worsen diabetic retinopathy, UK pharmacy guidance reports.[4] Anyone with existing eye disease should make sure their prescriber knows.

Heart rate

A small increase in resting heart rate has been observed with semaglutide, according to UK pharmacy guidance.[4]

Mood changes

Mood changes have been reported among the effects to watch for, according to one UK online-clinic guide.[5] If you notice a change in mood, raise it with your prescriber rather than pushing through.

The thyroid class warning

In the United States, semaglutide carries a boxed warning about a risk of thyroid C-cell tumours, including medullary thyroid carcinoma. It is a class warning based on studies in rodents, and it is why the medicine is not used in people with certain thyroid or endocrine conditions.[1]

In practice this means being alert to the symptoms UK pharmacy guidance lists as things to report — a lump in the neck or hoarseness — while remembering the evidence for a human risk comes from animal data.[4] If you have a personal or family history of thyroid cancer, this is a conversation to have with a prescriber before anything else.

Who should not take it: contraindications

A contraindication means the medicine should not be used at all. For the Wegovy pill, the contraindications reported at approval are:[1]

  • A personal or family history of medullary thyroid carcinoma (MTC)
  • Multiple Endocrine Neoplasia syndrome type 2 (MEN 2) — a rare inherited condition that raises the risk of certain tumours

Pregnancy. The tablet is not suitable in pregnancy. Because semaglutide has a long half-life — meaning it takes a while to clear from the body — UK pharmacy guidance reports that women planning a pregnancy should stop treatment at least two months beforehand.[4] If you could become pregnant, this is another point to settle with a prescriber before starting.

Key takeaway

The Wegovy pill is a prescription-only medicine for a reason: the common side effects are manageable for most people, but the serious risks and contraindications need a prescriber who knows your full history and other medicines. It is one option a prescriber may discuss, never something to start on your own. How its side-effect profile compares with the injection is covered on our pill vs injection page.

Reporting a side effect: the Yellow Card scheme

If you take any medicine and have a side effect, you are encouraged to report it. The MHRA Yellow Card scheme collects reports of suspected side effects, which helps the regulator monitor the safety of medicines in real-world use.[6] You do not need to be certain the medicine caused the problem to report it.

Reporting is not a substitute for medical care. For anything severe or sudden — persistent stomach pain, signs of an allergic reaction, or symptoms that worry you — seek urgent help first, and speak to your GP or pharmacist about any side effect that does not settle.

Frequently asked questions

What are the most common side effects of the Wegovy pill?

They are mostly gut-related: nausea, diarrhoea, vomiting, constipation and stomach pain, plus headache, tiredness, indigestion, dizziness, bloating, belching and low blood sugar.[1] In OASIS 4, gastrointestinal side effects affected about 74% of people on oral semaglutide 25 mg versus about 42% on placebo, and were mostly mild to moderate.[2]

Do the side effects get better over time?

For most people the gut side effects are described as mild to moderate and transient,[2] and UK pharmacy guidance reports they are worst while the dose is being increased.[4] The dose is stepped up slowly — 1.5 mg, then 4 mg, 9 mg and 25 mg, with at least a month at each step[3] — which UK pharmacy guidance says is designed to reduce them.[4] Whether to slow down, hold or stop is a decision for the prescriber.

What are the serious risks of the Wegovy pill?

Semaglutide carries a boxed warning in the US about a risk of thyroid C-cell tumours, based on animal studies.[1] Other risks UK pharmacy guidance says to watch for include acute pancreatitis, gallbladder problems, kidney injury from dehydration, low blood sugar when combined with insulin or sulphonylureas, a possible temporary worsening of diabetic eye disease, and a small rise in resting heart rate.[4] Seek urgent help for severe, persistent stomach pain.

Who should not take the Wegovy pill?

It is contraindicated in people with a personal or family history of medullary thyroid carcinoma (MTC) or Multiple Endocrine Neoplasia syndrome type 2 (MEN 2).[1] It is not suitable in pregnancy, and UK pharmacy guidance reports that women planning a pregnancy should stop at least two months beforehand.[4] Suitability is always assessed by a prescriber.

How do I report a side effect?

Report suspected side effects through the MHRA Yellow Card scheme and speak to your GP or pharmacist.[6] Reporting helps the regulator monitor the safety of medicines. For severe or sudden symptoms, seek urgent medical care rather than waiting.

References

  1. Novo Nordisk. FDA approval of the Wegovy pill (oral semaglutide 25 mg) — company announcement and accompanying approval press release (also distributed via PR Newswire): source for the tablet containing semaglutide (the same active ingredient as the Wegovy injection), the 25 mg once-daily maintenance dose, the list of most common side effects, the safety profile described as comparable to the injectable and to earlier semaglutide trials, the boxed thyroid C-cell warning and the MTC/MEN 2 contraindications. novonordisk.com
  2. American College of Cardiology. OASIS 4 trial summary (oral semaglutide 25 mg; published in the New England Journal of Medicine, 17 September 2025) — gastrointestinal adverse-event rates and discontinuation figures (secondary source).
  3. The Pharmaceutical Journal. "MHRA approves semaglutide oral tablets for weight loss" — UK titration ladder (1.5 mg → 4 mg → 9 mg → 25 mg, minimum one month per step) and the note that patients already on the 2.4 mg once-weekly semaglutide injection can be transitioned directly to the 25 mg once-daily tablet (secondary source).
  4. UK pharmacy patient guide to the Wegovy pill — warnings and precautions (pancreatitis, gallbladder disease, dehydration/kidney injury, hypoglycaemia with insulin or sulphonylureas, diabetic retinopathy, resting heart rate, thyroid symptoms to report), the note that gut side effects are worst during dose escalation, and the pregnancy caution (consumer-facing secondary source; single source, not the official product information — treat with caution).
  5. UK online-clinic guidance for the Wegovy pill — mood changes reported among effects to watch (secondary source; single source — treat with caution).
  6. MHRA. Yellow Card scheme — report a suspected side effect. yellowcard.mhra.gov.uk