Weight-loss pills and tablets explained

Weight-loss pills vs injections: what’s the difference?

In 2026, 2 new weight-loss pills were approved in the UK: Wegovy (semaglutide) and Foundayo (orforglipron).

Both medicines work in a similar way to weight-loss injections, including Mounjaro (tirzepatide) and the injectable version of Wegovy (semaglutide).

Weight-loss injections have been shown to be an effective treatment for excess weight or obesity, which can both increase the risk of health problems, such as heart attack and stroke.

However, these injections need to be stored in a fridge and self-injected every week. In comparison, taking a Foundayo or Wegovy pill every day might be more convenient for some people.

These pills may be as effective, or even more effective, than some injections. For example, research suggests the Wegovy pill leads to slightly more weight loss than the Wegovy injection.

But, like weight-loss injections, these pills should not be considered a “quick fix” for weight loss.

According to the Medicines and Healthcare products Regulatory Agency (MHRA), they must be prescribed alongside other healthy lifestyle changes, such as a reduced-calorie diet and increased physical activity.

These changes can help to maintain weight loss if you stop taking weight-loss medicines.

• Read more about what happens when you stop taking Mounjaro injections.

How do weight-loss pills work?

The Wegovy pill and Foundayo are the first GLP-1 agonist tablets to be approved in the UK and they work in the same way as the Wegovy injection and Mounjaro.

They all mimic a hormone called GLP-1 (glucagon-like peptide-1) in the body. GLP-1 agonists were originally prescribed to lower blood sugar levels in people with type 2 diabetes. 

But they also lower appetite, slow down digestion and increase fullness after eating, which can help people eat less and lose weight.

However, other non-GLP-1 weight-loss pills have been available in the UK for many years.

This includes orlistat (the generic name of Xenical, Orlos and Alli) and naltrexone-bupropion (Mysimba).

Orlistat stops around a third of the fat in your food being absorbed into your body, which reduces your energy (calorie) intake.

And naltrexone-bupropion affects 2 chemical messengers in your brain called dopamine and norepinephrine, which can lower your appetite and reduce food cravings.

What’s the best GLP-1 pill for weight loss?

Wegovy pill (semaglutide)

In June 2026, the Wegovy pill was approved for weight loss and weight management in UK adults with either:

• a BMI (body mass index) of 30 or above
• a BMI of 27 or above, and at least 1 weight-related health problem.

It’s a daily pill with a starting dose of 1.5mg a day. This can increase to 4mg, 9mg or 25mg, with a minimum of 1 month at each dose.

Semaglutide is the active ingredient in several different medicines, but only the Wegovy pill and injection are approved for weight loss and weight management in the UK.

Out of these medicines, only the Wegovy pill is not yet offered on the NHS. It still needs to be reviewed by the National Institute of Health and Care Excellence (NICE), so it’s currently only available through private prescription.

• Read more about who is eligible for the Wegovy injection on the NHS.

Is the Wegovy pill effective?

Research has shown the Wegovy pill is an effective treatment for weight loss.

A clinical trial in the New England Journal of Medicine in 2025 found people lost 13.6 per cent of their body weight after taking a daily pill with up to 25mg of semaglutide for 15 months (64 weeks).

Some studies have even suggested the pill may be more effective than the injection.

A 2026 review published in the British Medical Journal (BMJ) found people lost slightly more weight on the Wegovy pill (10.9 per cent ) than the injection (9.8 per cent) when compared to lifestyle changes alone.

However, there is evidence the Wegovy injection has benefits for heart health.

A study in the New England Journal of Medicine in 2023 found that people with cardiovascular disease (CVD) and excess weight or obesity given the Wegovy injection were 20 per cent less likely to have a heart attack, stroke or die from coronary heart disease than those given a dummy injection (placebo) over around 3 years.

More research is needed to see if the pill can also lower the risk of a heart attack or stroke in people with CVD.

Foundayo (orforglipron)

In August 2026, the MHRA approved Foundayo for weight loss and weight management in UK adults with either:

• a BMI of 30 or above
• a BMI of 27 or above, and at least 1 weight-related health problem.

The starting dose is 0.8mg per day, increasing to 2.5mg, 5.5mg, 9mg, 14.5mg and 17.2mg, with a minimum of 1 month at each dose.

Is Foundayo effective?

In a 72-week trial in the New England Journal of Medicine in 2025, people taking 12mg of orforglipron per day lost 8.4 per cent of their body weight, while those taking 36mg lost 11.2 per cent.

Some research has also suggested that orforglipron could help people maintain weight loss after they stop taking weight-loss injections like Mounjaro.

Are there GLP-1 pills for type 2 diabetes?

Rybelsus (semaglutide) is a GLP-1 agonist pill that is already licensed on the NHS to improve blood sugar levels in people with type 2 diabetes.

A study published in Advances in Therapy in 2024 of 333 UK adults with type 2 diabetes found that after taking Rybelsus for around 8 to 10 months, their blood sugar levels (HbA1C) decreased by 12.2mmol/mol and they lost 4.8kg on average.

Foundayo is also approved to treat people with type 2 diabetes whose blood sugar is poorly controlled, but is not yet available on the NHS.

What are the side effects of GLP-1 pills?

The reported side effects of GLP-1 agonist pills are similar to the side effects of weight-loss injections.

More than 1 in 10 people taking the Wegovy pill (semaglutide) or Foundayo (orforglipron) will experience digestive problems, according to the patient leaflets that come with each medicine. These include:

• feeling or being sick
• diarrhoea
• constipation
• stomach pain.

Other side effects include headaches, dizziness, gallstones and hair loss.

GLP-1 medicines also increase the risk of an inflamed pancreas (acute pancreatitis), which can be life-threatening.

It’s estimated that up to 1 in 100 people who take these drugs will develop this condition.

If you notice any symptoms, such as a sudden severe pain in the middle of the abdomen that does not go away, speak to your GP or call NHS 111 immediately.

If you have type 2 diabetes and have diabetic eye disease (diabetic retinopathy), semaglutide – the active ingredient in Wegovy and Rybelsus – may make your condition worse.

And in very rare cases, semaglutide has been linked to NAION (non-arteritic anterior ischaemic optic neuropathy), which causes sudden loss of vision in one eye at a time.

It’s also worth keeping in mind that rapid weight loss can lead to reduced muscle and bone mass, as well as fat loss.

This means it’s important to eat a balanced diet with enough protein and regularly do strength exercises to maintain muscle and bone mass while taking GLP-1 pills.

• Read the British Dietetic Association’s guide to eating well while taking weight-loss medications.

What about GLP-1 alternatives?

Orlistat (Xenical, Orlos or Alli)

Orlistat stops your body from absorbing a third of the fat in your food, which lowers your overall calorie intake.

It’s known by a few different brand names, including Xenical, which is available as a prescription, and Orlos or Alli, which are lower doses you can buy over the counter.

It comes as pills that are typically taken 3 times a day.

If you get it as a prescription, each tablet has a dose of 120mg, while over-the-counter versions have 60mg.

You can be prescribed orlistat on the NHS if you have either:

• a BMI of 30 or above
• a BMI of 28 or above and at least 1 weight-related health problem.

While studies suggest orlistat is less effective than GLP-1 pills, research shows it can still support weight loss.

For example, research in the journal Obesity in 2025 found people lost 5.1 per cent of their body weight after taking 120mg of orlistat every day for 6 months.

Orlistat side effects

Some people may experience some side effects while taking orlistat, especially after eating foods that are very high in fat. Common side effects include:

• fatty or oily poo
• diarrhoea
• urgent or more frequent bowel movements
• flatulence with or without oily spotting
• stomach pain.

Check with your doctor before you start taking orlistat, as it does not mix well with certain medicines, including:

• medicines to prevent blood clots (anticoagulants), such as warfarin
• medicines to treat abnormal heart rhythms (arrhythmias), such as amiodarone.

Naltrexone-bupropion (Mysimba)

Naltrexone and bupropion are the 2 active ingredients in the weight-loss pill Mysimba. They affect chemical messengers (neurotransmitters) in the brain to reduce appetite.

It’s available on private prescription for UK adults with a BMI of 30 or above, or a BMI of 27 and above with a weight-related health problem.

It’s not offered on the NHS. In its latest review, NICE did not find the drug was good value for money due to high costs and a lack of certainty on its long-term effectiveness.

Research suggests the drug does lead to some weight loss, at least in the short term.

A review published in the British Journal of Clinical Pharmacology of 4 trials found that people taking naltrexone-bupropion lost 2.5kg more weight than people taking a dummy pill for 12 months.

Mysimba side effects

According to the patient leaflet that comes with Mysimba, more than 1 in 10 people taking the drug may experience feeling or being sick, constipation, and headaches.

Other common side effects include dizziness, anxiety and difficulty sleeping.

What weight-loss tablets are available on the NHS?

The Wegovy pill (semaglutide) and Foundayo (orforglipron) are still being reviewed by NICE, so GLP-1 pills are not yet offered for weight loss on the NHS and are only available via private prescription.

If you have type 2 diabetes, you can be prescribed Rybelsus (semaglutide) on the NHS to manage your condition, but not for weight loss.

Orlistat is the only weight-loss pill currently available on the NHS.

It can be offered to UK adults with a BMI of 30 or above, or a BMI of 28 or above and at least 1 weight-related health problem.

Can you get pills for weight loss over the counter?

While most weight-loss pills are only available as a prescription, you can buy a lower dose of orlistat from a pharmacy under the brand names Orlos or Alli.

It’s a good idea to speak to your doctor first before you buy orlistat, especially if you have other health conditions.

Even though Orlos or Alli do not require a prescription, you still need to have a BMI of 28 or above to buy these medicines.

You may see other over-the-counter supplements and tablets being sold in pharmacies that claim to help you lose weight. However, there is little evidence that these are effective for weight loss.

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