Weight Loss Tablets in the UK: What's Licensed and What the Evidence Says

Several weight loss tablets are licensed in the UK, but they differ hugely in how they work and how much weight people lose. The longest-established is orlistat, which reduces fat absorption and is available on prescription (Xenical) or from pharmacies (Alli). Naltrexone/bupropion (Mysimba) is licensed but not recommended for NHS use. In 2026 two GLP-1 tablets were authorised for weight management: Wegovy tablets (oral semaglutide) in June and Foundayo (orforglipron) in August. These produce much more weight loss on average than older tablets. Everything else sold as a "slimming pill" is either a supplement without good evidence or, in some cases, an illegal and potentially dangerous product.

What "licensed" means

In the UK, a medicine must be authorised by the Medicines and Healthcare products Regulatory Agency (MHRA) before it can be marketed. The MHRA reviews evidence on quality, safety and effectiveness for a specific use. Its decision is set out in the Summary of Product Characteristics (SmPC), which you can read on medicines.org.uk.

Licensing also decides how a medicine can be supplied:

• Prescription-only medicines (POM) need a prescription from a qualified prescriber.
• Pharmacy medicines (P) can be sold without a prescription, but only in a pharmacy under a pharmacist's supervision.
• General sales list (GSL) medicines can be sold in shops.

No weight-loss medicine is on the general sales list. Food supplements, by contrast, are regulated as foods. They do not need to prove they work, and they cannot legally claim to treat or prevent disease.

A separate step, NICE appraisal, decides whether the NHS in England will fund a licensed medicine and for whom.

Licensed weight loss tablets at a glance

Weight-loss figures are trial averages alongside diet and activity advice and vary by trial design. Rybelsus is not included because it is licensed only for type 2 diabetes.

Orlistat

How it works

Orlistat blocks lipase, an enzyme in the gut that breaks down fat. Taken with meals, it stops roughly a third of the fat you eat from being absorbed; the undigested fat passes out in the stools. It does not act on appetite.

Forms and doses

• Xenical and generic orlistat 120mg are prescription-only, taken up to three times a day with meals that contain fat.
• Alli (orlistat 60mg) is a pharmacy medicine for adults with a BMI of 28 or more, used alongside a reduced-calorie, lower-fat diet.

Evidence

The most widely cited long-term trial is XENDOS (Diabetes Care, 2004), which followed more than 3,000 adults with obesity for four years. People taking orlistat with lifestyle changes lost more weight than those on placebo with lifestyle changes (on average a few kilograms more), and were less likely to develop type 2 diabetes, particularly if they had impaired glucose tolerance at the start.

NICE's obesity guidance includes orlistat as an option for some adults, and advises reviewing treatment after a period to check whether meaningful weight loss has occurred before continuing.

Side effects

Orlistat's side effects are mainly digestive and are linked to how much fat you eat: oily stools, urgency, wind with oily discharge and, sometimes, faecal incontinence. A lower-fat diet reduces these effects. Because orlistat reduces absorption of fat-soluble vitamins (A, D, E and K), a multivitamin taken at bedtime is often advised. It can interact with some medicines, including ciclosporin, levothyroxine, warfarin, some antiepileptics and the contraceptive pill if it causes severe diarrhoea.

Our guide to orlistat vs GLP-1 medications compares the two approaches in detail.

Naltrexone/bupropion (Mysimba)

Mysimba combines naltrexone (used for addiction) and bupropion (an antidepressant and smoking-cessation medicine). Together they act on appetite and reward centres in the brain. It is licensed in the UK for weight management in adults with a BMI of 30 or more, or 27 or more with a weight-related condition.

NICE TA494 (2017) did not recommend naltrexone/bupropion for NHS use, because it was not considered cost-effective. It is therefore mainly available privately. It has a number of contraindications and cautions, including uncontrolled high blood pressure, a history of seizures, some psychiatric conditions and use with opioids. Prescribers will also consider possible effects on mood. Like other medicines, it is reviewed after a period of treatment to see whether it is working.

GLP-1 tablets

The arrival of GLP-1 tablets in 2026 changed the picture for oral weight-management treatment.

Wegovy tablets (oral semaglutide)

The MHRA authorised Wegovy tablets on 11 June 2026 for adults with a BMI of 30 or more, or 27 to 30 with at least one weight-related condition, alongside diet and activity. According to the SmPC:

• Doses start at 1.5mg daily and step up monthly through 4mg and 9mg to 25mg.
• Tablets are taken on an empty stomach with a sip of water (up to 120ml), with a 30-minute wait before eating, drinking or taking other tablets.

In OASIS 4 (NEJM, 2025), adults taking 25mg daily lost an average of 13.6% of their body weight over 64 weeks, compared with 2.2% on placebo. Our oral semaglutide guide explains the evidence and practicalities.

Foundayo (orforglipron)

The MHRA authorised Foundayo on 10 August 2026 for weight management in adults (same BMI criteria) and for type 2 diabetes. It is a small-molecule, non-peptide GLP-1 drug, so it can be taken at any time of day without food or water restrictions. According to the SmPC, doses start at 0.8mg daily and can increase in steps, each after at least 30 days, up to a maximum of 17.2mg.

In ATTAIN-1 (NEJM, 2025), the highest dose led to an average weight loss of 12.4% at 72 weeks, compared with 0.9% on placebo. Our Foundayo guide covers the details, including an important interaction with oral contraceptives.

Rybelsus: not for weight loss

Rybelsus is also oral semaglutide, but at lower doses and licensed only for type 2 diabetes. People with diabetes often lose some weight on it, but it is not licensed or dosed for weight management. Our guide to Rybelsus and weight loss explains why.

How the options compare

Injections are not included here, but for completeness: Wegovy injections, Mounjaro and Saxenda are also licensed for weight management. Our guide to every weight loss medication available in the UK brings tablets and injections together, and tablets vs injections compares the GLP-1 options.

Supplements and "slimming pills"

Many products sold as weight loss tablets are not medicines at all.

Food supplements

Products containing ingredients such as green tea extract, garcinia cambogia, raspberry ketones, glucomannan, chromium or caffeine are sold widely online and in shops. Some, such as glucomannan, have weak evidence of small effects; most have little or none. Products described as "natural GLP-1", "GLP-1 support" or similar are not GLP-1 medicines and have not been shown to produce comparable weight loss. High-dose green tea extract has been linked to liver injury in rare cases.

Food supplements cannot legally claim to treat obesity or any other disease. If a supplement advertises dramatic weight loss, be sceptical.

Illegal and unlicensed slimming pills

The MHRA regularly seizes illegal slimming products. Some have been found to contain:

• Sibutramine, a former prescription weight-loss drug withdrawn in Europe in 2010 because of increased cardiovascular risk.
• Phenolphthalein, a laxative withdrawn because of cancer concerns.
• DNP (2,4-dinitrophenol), an industrial chemical that is extremely toxic and has caused deaths in the UK. It is not a medicine and is never safe to take.
• Undeclared prescription medicines, including diuretics and antidepressants.

Unlicensed "GLP-1 tablets" or "semaglutide drops" sold online may contain the wrong dose, the wrong substance or nothing at all. Our guide to fake and unlicensed weight loss jabs explains how to spot unsafe sellers, and the same principles apply to tablets.

Why some weight loss pills were withdrawn

The history of weight-loss tablets explains why regulators are cautious and why licensing matters. Several medicines that were once prescribed for weight loss were later withdrawn:

• Fenfluramine and dexfenfluramine were withdrawn worldwide in 1997 after being linked to heart valve disease and pulmonary hypertension.
• Rimonabant was suspended in Europe in 2008 because of an increased risk of psychiatric side effects, including depression.
• Sibutramine was suspended in Europe in 2010 after a large trial showed an increased risk of heart attacks and strokes in people with existing cardiovascular disease.

These withdrawals are why modern weight-loss medicines are expected to show cardiovascular safety, and why the SELECT trial, which showed semaglutide injections reduced cardiovascular events, was considered such an important result. They are also why sibutramine turning up in illegal slimming pills is so concerning.

How to judge weight loss claims

Whether you are reading an advert, a social media post or a news story, a few questions help separate evidence from marketing:

• Is it a licensed medicine? Check the name on medicines.org.uk or ask a pharmacist.
• What was it compared with? Good evidence compares a treatment with placebo or another treatment in a randomised trial. Before-and-after pictures and testimonials are not evidence.
• How long was the study? Weight-loss trials for licensed medicines typically last more than a year. Short studies can overstate effects.
• How much weight, and in whom? Look for average weight loss as a percentage, and whether the people studied are similar to you.
• What happened to people who stopped? Weight tends to return after most treatments are stopped.
• Who is making the claim? Be wary of sellers who profit from the product and do not cite independent sources.

Realistic expectations

Even with the most effective licensed tablets, results vary. In OASIS 4, about three-quarters of people on oral semaglutide 25mg lost at least 5% of their body weight, which means about a quarter did not. In ATTAIN-1, about one in five people on the highest orforglipron dose lost at least 20%, while others lost much less. A 5–10% weight loss can still bring meaningful health benefits, such as lower blood pressure and better blood glucose. Our guide to realistic weight loss expectations explains what to expect and how progress is usually reviewed.

How to get a licensed weight loss tablet safely

Through the NHS

Talk to your GP. They can discuss whether a medicine is appropriate alongside other support, such as a local weight management programme. NHS access to medicines depends on NICE guidance and local services. At the time of writing, GLP-1 tablets were not routinely available on the NHS for weight management.

Through a pharmacy

For Alli, a pharmacist will ask about your weight, health and other medicines before deciding whether to supply it.

Through a private prescriber

Regulated online pharmacies and online doctor services can prescribe licensed weight-loss tablets after an assessment. Good practice includes verifying your identity and weight, asking about your medical history and medicines, and, with your consent, informing your GP. Our provider comparison only includes regulated UK services, and our guide to how to choose an online pharmacy for weight loss explains what to check, including registration with the General Pharmaceutical Council (GPhC).

Costs vary by medicine, dose and provider. Our prices page explains what affects them.

Who should be cautious

A prescriber will assess suitability. Weight loss tablets may not be appropriate, or need extra care, if you:

• are pregnant, planning pregnancy or breastfeeding
• are under 18 (most are licensed for adults only)
• have a history of an eating disorder
• have pancreatitis or gallbladder disease (GLP-1 tablets)
• have chronic malabsorption or cholestasis (orlistat)
• have uncontrolled high blood pressure, seizures or take opioids (naltrexone/bupropion)
• take medicines that interact, such as the contraceptive pill (Foundayo), levothyroxine or warfarin

Our guide to who shouldn't take GLP-1 medications covers the GLP-1 tablets in more detail.

Tablets are one part of treatment

Every licensed weight-management tablet is authorised alongside a reduced-calorie diet and increased physical activity. Trials included dietary advice and activity goals, and results without them may be smaller. Weight also tends to return after stopping effective treatment. Building sustainable habits, getting enough protein and doing regular strength training can help support results. Our guides to what to eat on GLP-1 medication and preserving muscle offer practical advice.

When to speak to a professional

Speak to your GP, pharmacist or prescriber if:

• You are thinking about a weight loss tablet and want to know which options are suitable for you.
• You take other regular medicines, including the contraceptive pill, levothyroxine, warfarin or antidepressants.
• You have a history of an eating disorder, depression or seizures.
• You are pregnant, planning pregnancy or breastfeeding.
• You have side effects that are affecting your daily life.
• You have bought a slimming product online and are unsure whether it is safe.

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.
• Pain in the upper right abdomen, fever, or yellowing of the skin or eyes.
• Persistent vomiting or diarrhoea with signs of dehydration.
• A high temperature, fast heartbeat, heavy sweating or difficulty breathing after taking an unlicensed slimming product.
• Thoughts of self-harm or suicide, or a sudden change in mood.

For more on tablet treatments, visit our oral GLP-1 hub. Any decision about weight-loss medicine should be made with a qualified prescriber who knows your medical history.