Medics have issued a warning over a side effect of a popular medication.
Semaglutide treatments such as Ozempic and Wegovy have taken the internet by storm for their role in treating diabetes, as well as their additional benefit of supporting weight loss.
Although Ozempic is not officially approved as a weight-loss drug and is primarily prescribed to treat diabetes, its appetite-suppressing effects mean that, when combined with diet and exercise, it can help people lose weight.
There is one negative side effect, however, that has now been highlighted by doctors which could have a serious impact on patients who are using the medication.
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Side effects are unfortunately a part of nearly all medications, even everyday ones like paracetamol, and clinicians and patients have to weigh up whether the benefit outweighs the risk.
So what is this side effect?
The UK government website advises: "It typically causes sudden, painless vision loss, usually in one eye that is often described as a blurring or cloudiness of vision."
A study carried out in 2025 looked into complications around vision for patients from the US, including in Utah, Minnesota, New York, West Virginia and Ohio, who were taking semaglutide.
It found that the average age for people affected by this was 57, and that 56 percent of affected patients were women.
Among them was one woman in her 50s who experienced 'painful vision loss' in her left eye after her first injection of the medication.
A statement from the UK's Medicines and Healthcare products Regulatory Agency (MHRA) also drew attention to the risk.
It said: "Patients taking semaglutide who notice a sudden change in their eyesight, such as sudden impairment to their vision, or if eyesight gets worse very quickly in one or both eyes, should urgently attend eye casualty or A&E."
It is estimated that approximately 1 in 10,000 patients who take semaglutides could experience this side effect, making it a relatively rare effect.
MHRA chief safety officer Dr Alison Cave said: "While the potential risk of NAION (non-arteritic anterior ischemic optic neuropathy) for patients prescribed semaglutide is extremely small, it is important that patients and healthcare professionals are alert to the associated symptoms."
A representative for Novo Nordisk told UNILAD: "Patient safety is our top priority, and we take any reports about adverse events from the use of our medicines very seriously. We work closely with authorities and regulatory bodies from around the world to continuously monitor the safety profile of our products."
The statement added: "Based on the totality of evidence, we concluded that the data did not suggest a reasonable possibility of a causal relationship between semaglutide and NAION and Novo Nordisk believes that the benefit-risk profile of semaglutide remains favourable."
Kit Roberts