Semaglutide in the UK: Wegovy, Ozempic and Rybelsus Explained

Semaglutide is a once-weekly or once-daily GLP-1 medicine made by Novo Nordisk. In the UK it is available under three brand names: Wegovy (injections and, since June 2026, tablets) for weight management and cardiovascular risk reduction, Ozempic (injections) for type 2 diabetes, and Rybelsus (tablets) for type 2 diabetes. They share the same active ingredient, but they are licensed for different conditions, come in different doses and devices, and are not interchangeable. All are prescription-only. This guide explains how each product works, who it is for, what the evidence shows and how they are regulated in the UK.

What semaglutide is and how it works

Semaglutide belongs to a class of medicines called GLP-1 receptor agonists. GLP-1 (glucagon-like peptide-1) is a hormone released by the gut after eating. It signals to the brain that you are full, slows the rate at which food leaves the stomach, and helps the pancreas release insulin when blood glucose is high.

Natural GLP-1 breaks down within minutes. Semaglutide has been chemically modified so it lasts much longer in the body, with a half-life of about a week. That is why the injectable forms only need to be taken once a week.

Its main effects relevant to weight are:

• Reduced appetite and increased fullness, through action on appetite centres in the brain.
• Slower stomach emptying, which helps people feel full for longer but also contributes to side effects such as nausea.
• Changes in food preferences reported by some people, such as less interest in high-fat foods.

For blood glucose, semaglutide increases insulin release and reduces glucagon release when glucose is high, which lowers HbA1c in people with type 2 diabetes. Because this effect depends on glucose levels, semaglutide alone has a low risk of hypoglycaemia, although the risk rises when it is combined with insulin or sulfonylureas.

Our guide to how Wegovy works explains the biology in more depth, and What are GLP-1 medications? puts semaglutide in the context of the wider class.

The semaglutide products available in the UK

Doses and licence wording are summarised from the SmPCs and MHRA announcements. Always check the current SmPC on medicines.org.uk for exact details.

Wegovy injection

Wegovy was authorised in the UK for weight management in September 2021. It is licensed, alongside a reduced-calorie diet and increased physical activity, for adults with a BMI of 30 or more, or 27 to 30 with at least one weight-related condition. The SmPC also covers some adolescents aged 12 and over, under specific criteria; check the current SmPC for details.

Treatment starts at 0.25mg once weekly and increases every four weeks through 0.5mg, 1mg and 1.7mg to reach the 2.4mg maintenance dose. In January 2026 the MHRA authorised a higher maximum dose of 7.2mg weekly for adults with a BMI of 30 or more using Wegovy for weight management, given as three 2.4mg injections on the same day. Our Wegovy dosing schedule guide and pen guide explain how this works.

In 2024 the licence was extended to include reducing the risk of major adverse cardiovascular events in adults with established cardiovascular disease and overweight or obesity, based on the SELECT trial.

Wegovy tablets

The MHRA authorised Wegovy tablets for weight management on 11 June 2026, making them the first GLP-1 tablet licensed for weight management in the UK. The indication mirrors the injection's weight-management licence for adults. According to the SmPC:

• Treatment starts at 1.5mg once daily, increasing monthly through 4mg and 9mg to 25mg.
• Tablets are taken on an empty stomach with a sip of water (up to 120ml), at least 30 minutes before eating, drinking or taking other oral medicines.
• People on semaglutide 2.4mg injections can switch to 25mg tablets, starting a week after their last injection.

In the OASIS 4 trial (NEJM, 2025), adults taking 25mg daily lost an average of 13.6% of body weight over 64 weeks, compared with 2.2% on placebo. Our oral semaglutide guide covers the tablet in detail.

Ozempic

Ozempic is a once-weekly semaglutide injection licensed for adults with insufficiently controlled type 2 diabetes, alongside diet and exercise. Doses range from 0.25mg (a starting dose) to a maximum of 2mg weekly. It has been available in the UK since 2018.

Its evidence base comes from the SUSTAIN trial programme. SUSTAIN-6 (NEJM, 2016) showed a reduction in major cardiovascular events compared with placebo in people with type 2 diabetes at high cardiovascular risk, and later trials have studied effects on kidney outcomes in people with diabetes and chronic kidney disease.

Ozempic is not licensed for weight management. During the GLP-1 supply shortages of 2023 and 2024, UK health authorities advised that semaglutide products licensed for diabetes should be prescribed only for their licensed use, so that people with diabetes could continue treatment. Our Ozempic vs Wegovy guide explains the differences in detail.

Rybelsus

Rybelsus is a once-daily semaglutide tablet licensed for type 2 diabetes. Its evidence comes from the PIONEER trial programme. Because semaglutide is a peptide that is easily broken down in the stomach, the tablet contains an absorption enhancer and must be taken on an empty stomach with a small amount of water.

In 2025 a new formulation was introduced in the UK, replacing the original 3mg, 7mg and 14mg tablets with 1.5mg, 4mg and 9mg tablets that give equivalent exposure thanks to improved absorption. During the transition the two formulations co-existed, and UK health bodies warned about the risk of dosing errors. Rybelsus is not licensed for weight management, although people with diabetes often lose some weight. Our guide to Rybelsus and weight loss explains why.

Why the products are not interchangeable

Because they contain the same molecule, it is tempting to think of these products as interchangeable. They are not, for several reasons:

• Different licences. A product's licence defines the conditions and patients it has been assessed for. Prescribing outside the licence ("off-label") is possible in some circumstances but carries extra responsibility for the prescriber.
• Different doses. Wegovy goes up to 2.4mg (or 7.2mg) weekly; Ozempic to 2mg weekly. Oral doses are much larger in milligrams than injected doses because only a small proportion of an oral dose is absorbed.
• Different devices. Pens differ in how doses are selected and how many doses they contain. Using the wrong pen or dose can lead to errors.
• Different formulations. The two Rybelsus formulations, and Wegovy tablets, are not interchangeable milligram for milligram.

If you are moving between semaglutide products, your prescriber will advise on the right dose and timing.

What the evidence shows

Weight loss

These are trial averages in people without diabetes, alongside lifestyle support. People with type 2 diabetes typically lose less weight on GLP-1 medicines. Individual results vary, and in STEP 1 roughly one in seven people taking semaglutide lost less than 5% of their body weight. Our Wegovy results guide breaks down the STEP trials in more detail.

Weight maintenance

When semaglutide is stopped, weight tends to return. In STEP 4, people switched to placebo after 20 weeks regained weight, while those who continued kept losing. In the STEP 1 extension, people regained about two-thirds of their lost weight within a year of stopping. See our Wegovy maintenance guide.

Heart health

In SELECT (NEJM, 2023), semaglutide 2.4mg reduced major adverse cardiovascular events by 20% compared with placebo in 17,604 adults with established cardiovascular disease and a BMI of 27 or more, without diabetes. Our SELECT trial guide explains the findings and their limits.

How semaglutide compares with tirzepatide

Tirzepatide (Mounjaro) acts on both GLP-1 and GIP receptors. In the head-to-head SURMOUNT-5 trial (NEJM, 2025), tirzepatide produced greater average weight loss than semaglutide over 72 weeks. Semaglutide, however, has cardiovascular outcome evidence in people without diabetes from SELECT. Our Mounjaro vs Wegovy comparison and SURMOUNT-5 guide set out the details.

Side effects and safety

Side effects are broadly similar across semaglutide products, although they depend on dose. The most common are gastrointestinal:

• nausea
• diarrhoea
• vomiting
• constipation
• abdominal pain, indigestion, bloating and burping

These are most likely during dose increases and usually become milder over time. Eating smaller meals, stopping when full, and avoiding very fatty or rich foods can help.

Less common but important risks listed in the SmPCs include:

• Gallbladder problems, including gallstones.
• Acute pancreatitis, which is rare but serious.
• Dehydration and kidney problems, usually linked to severe vomiting or diarrhoea.
• Hypoglycaemia in people taking insulin or sulfonylureas.
• Worsening diabetic retinopathy in people with diabetes whose blood glucose falls rapidly.
• Non-arteritic anterior ischaemic optic neuropathy (NAION), a very rare eye condition causing sudden vision loss, now listed in semaglutide product information.
• Aspiration risk under anaesthesia, because of slower stomach emptying.

Semaglutide should not be used during pregnancy or breastfeeding. The SmPCs advise stopping at least two months before a planned pregnancy. Our Wegovy side effects guide covers management in detail.

How semaglutide is accessed in the UK

On the NHS

• Weight management: NICE TA875 recommends semaglutide (Wegovy) within specialist weight management services for adults who meet BMI and comorbidity criteria, for up to two years.
• Cardiovascular risk: NICE TA1152 (May 2026) recommends semaglutide for adults with established cardiovascular disease and a BMI of at least 27.
• Type 2 diabetes: Ozempic and Rybelsus are prescribed according to diabetes guidance.

Access varies by area. Our guide to Wegovy on the NHS explains referral and eligibility.

Privately

Wegovy injections and Wegovy tablets are available on private prescription from regulated providers, including online pharmacies and online doctor services. A private prescriber must assess you, usually including verification of your identity and weight, before prescribing. Our provider comparison explains how services differ. Costs vary by product, dose and provider; our prices page explains the factors that affect them.

Avoiding unsafe products

The MHRA has repeatedly warned about fake and unlicensed semaglutide sold online, through social media and in beauty settings. Warning signs include no prescription or consultation, vials or powders instead of branded pens or tablets, "research only" labelling and unusually low prices. Our guide to fake weight loss jabs explains how to check a supplier.

A short timeline of semaglutide in the UK

Dates are based on regulatory announcements, NICE publications and journal articles. Where a licence was granted at EU level before 2021, it applied in the UK at the time.

Interactions with other medicines

Semaglutide does not interact with many medicines in the way some drugs do through liver enzymes, but it can affect others in two main ways.

Slower stomach emptying. Because semaglutide delays gastric emptying, it can change how quickly other oral medicines are absorbed. This is usually not clinically important, but it matters more for medicines where precise levels are needed. The SmPCs mention:

• Warfarin and similar anticoagulants, where more frequent INR monitoring is advised when starting semaglutide.
• Levothyroxine, where Wegovy tablets increased exposure to thyroxine in studies, so thyroid levels may need monitoring.

Effects on blood glucose. Combining semaglutide with insulin or sulfonylureas increases the risk of hypoglycaemia, and doses of those medicines may need reducing.

Oral semaglutide specifically. Wegovy tablets and Rybelsus must be taken on an empty stomach, and other oral medicines should be taken at least 30 minutes later. This can require some planning if you take several medicines in the morning.

Contraception. Unlike tirzepatide, semaglutide is not generally associated with reduced effectiveness of oral contraceptives in its product information, but severe vomiting or diarrhoea from any cause can reduce absorption of the pill. Our guide to GLP-1 medicines and contraception explains the details.

Always tell your prescriber and pharmacist about all the medicines and supplements you take. Our guide to GLP-1 medication interactions covers this in more depth.

Who should not take semaglutide

A prescriber will assess whether semaglutide is suitable. It is generally not appropriate, or needs particular caution, if you:

• are pregnant, planning pregnancy or breastfeeding
• have had a serious allergic reaction to semaglutide or its ingredients
• have a history of pancreatitis
• have severe gastrointestinal disease, such as severe gastroparesis
• have diabetic retinopathy (if you have diabetes)
• have severe kidney or liver impairment
• have a history of an eating disorder

The SmPC for each product lists the full contraindications and warnings. Our guide to who shouldn't take GLP-1 medications covers this in more detail.

When to speak to a professional

Speak to your GP, pharmacist or prescriber if:

• You are considering semaglutide and want to know which product, if any, is right for you.
• You have type 2 diabetes and are taking insulin or a sulfonylurea, as doses may need adjusting.
• You are taking levothyroxine, warfarin or other medicines where absorption or levels need monitoring.
• Side effects are persistent or affecting your ability to eat and drink.
• You are planning pregnancy or have become pregnant.
• You are unsure which semaglutide product or dose you have been given.

Seek urgent medical help (NHS 111, or 999 in an emergency) if you have:

• Severe, persistent abdominal pain, which may spread to your back, with or without vomiting (possible pancreatitis).
• Pain in the upper right abdomen, fever, or yellowing of the skin or eyes (possible gallbladder problems).
• Persistent vomiting or diarrhoea with signs of dehydration.
• Sudden loss of vision or blurred vision in one eye.
• Signs of a severe allergic reaction, such as swelling of the face or throat or difficulty breathing.

For more on Wegovy, visit our Wegovy hub. Which semaglutide product, if any, is suitable for you is a decision for a qualified prescriber.