Starting a new medicine inevitably comes with one question:
“What side effects am I likely to get?”
With Wegovy pills, the most commonly reported problems involve the digestive system.
That will sound familiar to anyone who has read about GLP-1 medicines before.
What are the most common Wegovy pill side effects?
The MHRA lists common gastrointestinal effects including:
- nausea
- diarrhoea
- constipation
- vomiting
These effects are associated with semaglutide and may be more noticeable during dose increases.
Not everyone experiences them, and severity varies.
Why can Wegovy affect your stomach?
Semaglutide works partly by affecting appetite and digestion.
That is useful for weight management, but it can also mean the digestive system takes a little time to adjust.
This is one reason treatment begins at a lower dose and rises gradually rather than starting immediately at 25 mg.
Are side effects worse when the dose increases?
They can be.
The Wegovy pill schedule uses a gradual escalation from 1.5 mg to 4 mg, 9 mg and 25 mg, with at least a month at each stage.
If side effects are troublesome, speak to your prescriber rather than changing the dose yourself.
What should you do if you feel sick?
Follow the advice supplied by your prescriber and the medicine’s patient information leaflet.
Staying hydrated can be important if you are experiencing vomiting or diarrhoea.
If you cannot keep fluids down, symptoms are severe, or you become concerned about dehydration, seek medical advice.
Are there serious side effects?
Like all prescription medicines, semaglutide can cause less common but potentially important adverse effects.
Patients should read the Patient Information Leaflet supplied with their medicine and seek urgent medical advice if they develop symptoms described there as requiring immediate attention.
The MHRA also monitors semaglutide safety and has updated UK product information as new safety evidence has emerged.
What about sudden changes in vision?
The MHRA updated semaglutide information in February 2026 regarding a very rare eye condition called non-arteritic anterior ischaemic optic neuropathy (NAION).
It can cause sudden, painless loss of vision in one eye.
Anyone experiencing sudden or rapidly worsening vision should seek urgent medical attention.
Should you stop Wegovy if you get side effects?
Do not make significant treatment changes without discussing them with the healthcare professional responsible for your prescription, unless you have been instructed to seek emergency help.
Your prescriber may want to review your symptoms, dose or treatment plan.
Can you report suspected side effects?
Yes.
Suspected medicine side effects in the UK can be reported through the MHRA Yellow Card scheme.
Reporting helps regulators continue monitoring medicine safety.
The takeaway
Digestive symptoms such as nausea, diarrhoea, constipation and vomiting are among the most commonly reported Wegovy pill side effects.
Many people will want to know whether those symptoms are expected or whether they need medical advice.
When in doubt, contact your prescriber, pharmacist, NHS 111 or another appropriate healthcare service rather than relying on advice from social media.
For the full dose schedule and how the pill works, see our Wegovy pills UK prices and doses guide . If you are checking whether you may be eligible, read our who can take Wegovy pills guide .
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Health Compare UK provides general information and price comparison only. It does not provide individual medical advice or prescribe medicines. This article is for general information only and should not replace advice from a qualified healthcare professional.
Sources
- UK MHRA product information for Wegovy (semaglutide) oral pill, including common side effects.
- MHRA semaglutide safety update regarding NAION, February 2026.
- MHRA Yellow Card scheme for reporting suspected medicine side effects.
Information is provided for general informational purposes and should not replace advice from a qualified healthcare professional.