Are semaglutide tablets safe for weight loss?

You've just read that 74% of people in the trial had side effects — here's what that actually means

That figure comes from OASIS 4, the phase 3 trial underpinning the MHRA's June 2026 approval of Wegovy tablets. It sounds alarming at face value. But the detail matters: 74% of participants on oral semaglutide reported a gastrointestinal side effect at some point during 64 weeks, compared with 42% on placebo. The gap is real, but the nature of those effects is mostly nausea, loose stools or constipation, uncomfortable, not dangerous, and in the majority of cases mild to moderate. Serious adverse events were broadly similar between the treatment and placebo groups in the trial.

The dose-escalation schedule exists partly to manage this. Starting at 1.5mg once daily and working up through 4mg and 9mg before reaching the 25mg maintenance dose gives the body time to adjust at each step, with a minimum of one month at each level. Side effects tend to cluster around dose changes, then settle. The full breakdown of what to expect at each stage covers this in more detail, including practical ways most people reduce the worst of it.

The short version: a majority of people experience some digestive discomfort, especially early on. Most find it manageable. Stopping because of side effects happened in a minority of trial participants, and the rates were not dramatically different from those seen with the weekly injection at the same maintenance dose.

The side effects that genuinely need a prescriber's attention

There is a difference between 'common and expected' and 'rare but serious', and it's worth knowing both. If you want a thorough overview of what the side effects of semaglutide tablets are, that page brings together the full picture alongside guidance on when to act.

Acute pancreatitis is the most clinically significant risk. It is uncommon, but following its own review, the MHRA published a Drug Safety Update in January 2026 to remind patients and clinicians that severe, persistent abdominal pain (particularly pain that reaches into the back) requires urgent medical assessment. Do not wait and see with that symptom. Call 111 or go to A&E if the pain is severe.

Other signs that need prompt attention: gallbladder symptoms (sharp pain under the right ribs, especially after eating); signs of dehydration if vomiting or diarrhoea is prolonged (dizziness, dark urine, inability to keep fluids down); and any allergic reaction, swelling of the face, lips or throat, or difficulty breathing. These are rare. Knowing them matters because catching them early changes the outcome.

Low mood or thoughts of self-harm have been flagged across GLP-1 medicines as a class. The evidence for a causal link is limited, but it is taken seriously. Tell your prescriber if your mood changes noticeably after starting. You can also find further support through Mind if you need it.

Who this medicine is not right for, and the checks that happen first

Oral semaglutide is not suitable for everyone, and a prescriber works through several factors before issuing a prescription. The licensed population is adults with a BMI of 30 or above, or 27 to 29.9 with at least one weight-related health condition, but the BMI threshold alone does not settle the question.

The medicine is not recommended during pregnancy, breastfeeding, or when trying to conceive. It is not licensed for under-18s. People with a personal or family history of medullary thyroid carcinoma or MEN2, or with a history of pancreatitis, should discuss this carefully with a clinician before starting. Certain gastrointestinal conditions also warrant a conversation. More background on what oral semaglutide is and how it works may be helpful before that consultation.

At nume, a GPhC-registered Independent Prescriber personally reads every consultation, a real clinician, not a decision tree. Side-effect history, current medicines and relevant conditions are all part of that review. If you have questions about your own circumstances before you start, our team is available seven days a week. You can also read more about how we work and who our clinical team is on our about us page.

How to report a side effect and why it matters

Oral semaglutide for weight loss carries a Black Triangle (▼) in the UK, meaning the MHRA is actively collecting additional safety data. That is standard for newly approved medicines and does not mean they are more dangerous, it means the regulator wants robust real-world evidence to sit alongside the trial data.

If you experience a side effect (expected or unexpected) the right step is to report it via the MHRA Yellow Card scheme. You can do this yourself as a patient; you do not need to go through a doctor first. Reports from real users help build the evidence base that keeps future patients safer. The scheme also accepts reports about suspect medicines, which is relevant given that fake pens and unlicensed versions of GLP-1 products do circulate online. If you bought from an unverified source and are experiencing something unexpected, report that too.

Our FAQs page covers a number of common questions about starting treatment, including detail on semaglutide tablets side effects that patients ask about most often, and if you are moving through the escalation schedule you may also find it useful to read about what to expect specifically at the 7mg tablet stage or to check the side effects associated with the 14mg tablet dose as you step up. If you want to understand the broader weight-loss treatment options available before deciding, that's a sensible starting point. When you're ready to talk through your own suitability, speak to our prescribers via a free consultation, side effects and your individual risk factors are part of every clinical conversation we have.