About weight loss treatments

What weight loss treatments are available?

There are a range of different weight loss treatments available that can help you reach your desired weight. Whether you take weight loss injections or tablets, you’ll need to follow a diet and exercise plan to get the best results. Read on to learn more about the different types of weight loss medication available from ASDA Online Doctor to help you find the best treatment for you.

Weight loss medication

Weight loss medication is split into 2 categories: weight loss injections and weight loss tablets. The weight loss injections currently licensed for use in the UK are:

• Wegovy pill
• Wegovy
• Mounjaro
• Nevolat (generic liraglutide)

The weight loss tablets licensed for use in the UK are:

• Xenical
• orlistat
• Orlos
• alli
• Mysimba

You can start weight loss medication if you meet the prescribing guidelines for taking it. This usually involves having a certain body mass index (BMI) or weight-related health conditions, but each type of weight loss medication has different criteria. Most medications require a prescription, except alli and Orlos, which you can get over the counter, although a pharmacist or doctor still needs to check your suitability. When you take weight loss medications, you should commit to a low-calorie diet and regular exercise.

➤ Check your BMI to see what weight loss treatment you may be eligible for. You’ll just need a recent height and weight measurement.

Weight loss injections

Weight loss injections can reduce your appetite and make you feel fuller between meals. This is because they work on the parts of your brain responsible for hunger and appetite control. Wegovy and Mounjaro are taken once a week, while liraglutide is taken daily.

You can get weight loss injections through our service if you have a BMI of:

• 30 or above
• between 27 and 30 with a weight-related medical problem or risk factor, such as high blood pressure or sleep apnoea

Always be honest and accurate with your doctor. This is important because weight loss medication could cause serious illness and severe side effects if it is not suitable for you.

Wegovy (semaglutide)

Wegovy is an injection containing the active ingredient semaglutide, a glucagon-like-peptide-1 (GLP-1) receptor agonist.

How does it work?

Wegovy works the same way as GLP-1 in your body, which is a hormone produced in your intestines after eating. This hormone sends signals to your brain, making you feel satisfied and full after a meal. It also slows down digestion and stimulates the release of insulin, a blood sugar-lowering hormone.

How to take it?

Wegovy is injected under the skin once a week. It comes as pre-filled doses, starting at 0.25mg. You’ll gradually increase your dose during the first 20 weeks of treatment to allow your body to get used to the medication. Once you reach the maintenance dose of 2.4 or 7.2mg, you’ll stay on this until the end of your treatment.

How effective is it?

Wegovy can help people lose an average of 21% of their weight on the maintenance dose by 72 weeks.

Originally, semaglutide was used to treat type 2 diabetes under the name Ozempic, but doctors discovered that it was also an effective weight loss treatment. Wegovy contains semaglutide at a different dose, so it is only used to support weight loss. You can find out more about the differences between Mounjaro, Wegovy, and Ozempic in our comparison guide. ASDA Online Doctor doesn’t recommend taking medications for weight loss that are only licensed for type 2 diabetes.

Mounjaro (tirzepatide)

Mounjaro is another weight loss injection that works similarly to Wegovy. It’s used to treat both type 2 diabetes and obesity and contains the active ingredient tirzepatide.

How does it work?

Tirzepatide is a dual agonist, which means it mimics GLP-1 and glucose-dependent insulinotropic polypeptide (GIP), another hormone which our bodies produce after eating. Just like semaglutide, this hormone reduces appetite and helps you lose weight by making you feel fuller while eating less. Because Mounjaro and Wegovy contain different active ingredients, you may find one gives you fewer side effects than the other.

How to take it?

Mounjaro is injected into your abdomen or upper thigh once per week. You’ll follow a Mounjaro dosage schedule, starting from a dose of 2.5 mg per week. This can be gradually increased, usually every 4 weeks, to a maximum maintenance dose of 15 mg per week.

How effective is it?

Mounjaro has been proven to be an effective weight loss treatment in clinical trials. After 72 weeks on the highest maintenance dose (15mg) people lost an average 22.5% of their starting weight.

Nevolat (liraglutide)

Nevolat is another weight loss injection, but it contains the active ingredient liraglutide. Liraglutide injections used to be available under the brand name ‘Saxenda’, but Saxenda is now out of stock long term.

How does it work?

Nevolat reduces appetite and makes you feel fuller by mimicking the hormone GLP-1.

How to take it?

Nevolat needs to be injected once per day. This is because liraglutide breaks down in the body much faster than semaglutide or tirzepatide. Nevolat also follows a dosage schedule, which is increased over the first 5 weeks of treatment.

How effective is it?

Nevolat has been found to help people lose an average of 8% of their starting weight after taking the maintenance dose for 56 weeks, compared to 2.6% for patients taking a placebo.

Weight loss injections comparison

If you’re not sure which weight loss injection is best for you, we’ve created a comparison table with the 3 most common treatments. You can also discuss your suitability for each treatment with one of our doctors.

Weight loss tablets

Weight loss tablets work by either reducing your appetite (Wegovy and Mysimba) or stopping your body from absorbing some fat from your food (orlistat-based medications). The Wegovy pill is the first official GLP-1 weight loss tablet to become available in the UK. All weight loss tablets are taken daily.

Asda Online Doctor can prescribe Wegovy pills or Mysimba if you have a BMI of:

• 30 or more
• between 27 and 30 with a weight-related medical problem or risk factor, such as high blood pressure or sleep apnoea

You can be prescribed orlistat medication from Asda Online Doctor if your BMI is:

• above 30
• 28 or more, and you have a weight-related condition, such as type 2 diabetes, or a risk factor

Wegovy pill

The Wegovy pill is a GLP-1 medication, like Wegovy, Mounjaro, and Nevolat. It’s the first of its kind approved for weight loss in the UK. The active ingredient is semaglutide.

How does it work?

The Wegovy pill works by copying the effects of GLP-1, which helps regulate appetite by sending signals to the brain that you have eaten and feel full, and slows down digestion. This can help you feel satisfied for longer and reduce how hungry you feel between meals. It also causes your body to release insulin when needed, which helps manage blood sugar levels.

How to take it?

Take 1 Wegovy pill a day, when you first wake up. It must be taken on an empty stomach after a minimum of 8 hours of fasting, with only a sip of water (no more than about 120ml). You should then wait 30 minutes before eating, drinking, or taking any other oral medications. This helps the pill absorb in your stomach properly and take effect.

How effective is it?

In clinical trials, by week 64, people taking Wegovy 25mg once a day lost an average of 17% of their starting body weight. In comparison, people taking a placebo tablet with no active medication lost around 3% of their starting body weight over the same period.

Generic orlistat

Orlistat is a fat enzyme blocker. It’s an unbranded medication containing the active ingredient orlistat.

How does it work?

When you eat foods containing fat, enzymes in your gut break down the fat so that your body can absorb it. Orlistat blocks these enzymes from breaking down fat, which means your body will not be able to absorb as much of it. The fat will then pass out of your system when you go to the toilet. This means you absorb less fat, which leads to more weight loss.

How to take it?

You can take one 120mg orlistat tablet up to 3 times a day. You should take this either with or within 1 hour of a meal containing fat.

How effective is it?

In clinical trials, orlistat was found to help 37% of people lose 5% or more of their body weight after 12 weeks. 49% of these patients went on to lose 10% or more of their weight after a year of treatment.

Xenical

Xenical contains the fat enzyme blocker, orlistat.

How does it work?

It works the same way as generic orlistat, the only difference is that Xenical is a branded treatment made by a different manufacturer. Taking it with meals containing fat prevents around a third of the fat from your meal being absorbed.

How to take it?

You take one Xenical capsule up to 3 times a day, only with meals containing fat.

How effective is it?

In clinical trials, Xenical was found to help 37% of people lose 5% or more of their body weight after 12 weeks. Of these patients, 49% went on to lose 10% or more after 1 year of treatment.

Mysimba

Mysimba contains a combination of two active ingredients: naltrexone (8mg) and bupropion (90mg).

How does it work?

Naltrexone and bupropion affect the parts of your brain responsible for appetite and cravings. This reduces feelings of hunger and food cravings, making it easier to reduce your calorie intake without feeling hungry.

How to take it?

Mysimba is taken every day and follows a dosage schedule until you reach the maintenance dose: 2 tablets twice a day.

How effective is it?

In clinical trials, Mysimba has been proven to help people lose an average of 8.1% after 56 weeks of treatment.

Weight loss medications and effectiveness in clinical trials

Each weight loss medication is effective in its own right, which is why they’ve been approved for use in the UK. Each has been tested in clinical trials, although these often differ in how many patients were tested and at how many weeks. Below we look at the different clinical trials for each weight loss medication so you can get a better idea of how much weight you might lose. Remember, any weight loss medication is most effective when you follow a diet and exercise plan.

Weight loss medication	Effectiveness in clinical studies
Mounjaro	People lost up to 22.5% of their starting weight on the 15 mg maintenance dose after 72 weeks
Wegovy	People lost an average 21% of their starting weight after 72 weeks on the 7.2mg maximum maintenance dose
Wegovy pill	People lost 17% on average of their starting weight on the 25mg maintenance dose after 64 weeks
Nevolat (liraglutide)	People lost an average of 8% of their starting weight on the maintenance dose after 56 weeks
Orlistat	Found to help 37% of people lose 5% or more of their starting weight after 12 weeks
Xenical	Found to help 37% of people lose 5% or more of their starting weight after 12 weeks
Alli	Found to help 46.7% of people lose 5% or more of their starting weight after 6 months
Mysimba	People lost an average of 8.1% of their starting weight after 56 weeks of treatment

Are weight loss treatments available over the counter?

Yes, alli and Orlos are weight loss treatments available over the counter. alli and Orlos are brand names for over-the-counter orlistat. A pharmacist or doctor will discuss with you whether these treatments are suitable before you can buy them.

Each alli or Orlos capsule contains 60mg of orlistat, whereas prescription-strength Xenical contains 120mg of orlistat. We can prescribe alli or Orlos if you have a BMI of 28 or above. You take 1 capsule with a meal containing fat, up to 3 times a day, for no longer than 6 months.

You should take a daily multivitamin while taking alli, Orlos, or any other orlistat-based medication. If you take alli for 6 months and want to continue taking it, you need to see a doctor for their advice first.

Are weight loss treatments available on the NHS?

Yes, but only under certain circumstances. The NHS does offer weight loss medications, however, they normally expect you to try to lose weight without them first. If you are not able to lose weight without medication, you may then be put on a waiting list to see a specialist weight management service.

Once you’re able to access a specialist weight management service, you may be prescribed treatment. The NHS usually only prescribes weight loss injections if you have a BMI of:

• 35 or more
• 32.5 or more if you're of Asian, Chinese, Middle Eastern, Black African, or African-Caribbean origin
• 30 or more if you have a weight-related health condition like high blood pressure
• 27.5 if you have a weight-related health condition like high blood pressure and you're of Asian, Chinese, Middle Eastern, Black African, or African-Caribbean origin

If you are able to access a specialist weight management service and they approve treatment for you, you can get your medication on an NHS prescription. This means you would only need to pay the NHS prescription charge instead of the full price of your medication. You could get your treatment for free if you don’t normally pay for NHS prescriptions.

The exception to this is Mounjaro, which has been approved by the NHS for prescription from GPs. However, it’s currently undergoing a 12-year rollout plan, starting with people most in need of weight loss treatment due to their weight causing health complications. You can find out more about who is eligible for Mounjaro and other weight loss injections on the NHS in our guide.

Side effects of weight loss medications

You may experience some side effects when you take weight loss treatment tablets or injections.

Side effects from medications can vary depending on the treatment.

Common Mounjaro side effects:

• feeling sick (nausea)
• diarrhoea
• vomiting
• constipation
• low blood sugar (if used with certain diabetes medications)
• indigestion
• stomach pain
• dizziness
• allergic reactions
• low blood pressure
• hair loss
• feeling tired
• bloating
• burping
• gas
• reflux or heartburn
• injection site reactions
• an increased level of some pancreatic enzymes as shown in blood tests (such as lipase)
• increased calcitonin levels

Common Wegovy side effects:

• headache
• diarrhoea
• constipation
• nausea or vomiting (feeling or being sick)
• feeling weak or tired
• stomach pain
• upset stomach or indigestion
• dizziness
• burping
• gas
• bloating
• reflux or heartburn
• hair loss
• reactions at the injection site, like redness, swelling, or soreness
• gallstones
• inflamed stomach (gastritis), which can cause nausea, vomiting, and stomach ache
• low blood sugar in patients with diabetes, which is more likely if you’re taking sulfonylurea or insulin
• a change in the way food or drink tastes
• a change in skin sensations (dysaesthesia)

As the Wegovy injection and pill contain the same active ingredient, semaglutide, the side effects are the same. Always check the patient information leaflet included with your medication for specific details about side effects.

Common Nevolat (liraglutide) side effects:

• dizziness
• feeling weak
• changes to your sense of taste
• rash
• injection site reactions
• indigestion
• stomach inflammation (gastritis)
• stomach discomfort
• upper stomach pain
• heartburn
• feeling bloated
• wind
• belching
• dry mouth
• low blood sugar
• increase in the pancreatic enzymes, lipase and amylase

Common Xenical (orlistat) side effects:

• more frequent or urgent bowel movements
• oily rectal discharge
• soft or liquid bowel movements
• gas, sometimes with discharge
• headaches
• stomach pain or discomfort
• low blood sugar levels or bloating in people with type 2 diabetes
• rectal pain or discomfort
• not being able to hold in bowel movements
• menstrual cycle changes for women
• tiredness
• tooth or gum problems

Losing a lot of weight in a short time can have effects on your body too. When you lose weight, you might notice parts of your skin sagging where you have lost the weight. You may also have stretch marks, which are lines that can come up on your skin when your skin stretches and shrinks rapidly.

If you are female, your period can change. Being overweight might lead to irregular or missed periods, but your periods might also become more irregular when you are losing weight. When you reach a stable weight from weight loss treatment, you might notice that your periods become more regular.

Can I switch weight loss injections?

Yes, it is possible to switch from one weight loss injection to another. However, weight loss injections are not interchangeable, so you will need a doctor to review your request before changing treatment.

At ASDA Online Doctor, you can request to change from one weight loss injection to another between Mounjaro, Wegovy, and Nevolat. One of our doctors will review your request, check your medical history, and decide whether the new treatment is safe and suitable for you.

If your request is approved, your doctor will also advise when to stop your current medication and how to safely start the new one. In most cases, you’ll be able to leave just 7 days between your last dose of one treatment and your first dose of the other.

Switching from Mounjaro to Wegovy

If you are new to us, to change from Mounjaro to Wegovy, request Wegovy treatment and doctor will review your medical history and confirm whether you meet the eligibility criteria:

• BMI between 27 and 30 with a weight-related health condition, or
• BMI of 30 or above.

Already with us? Just fill in a quick health questionnaire via your patient account to request a switch. Often patients who are eligible for Mounjaro will also be eligible for Wegovy, but our doctors will always check to let you know if Wegovy is safe and suitable.

If approved by the doctor, this will be for the suitable starting dose of Wegovy based on your current Mounjaro dose. You will then need to wait 7 days after your last Mounjaro injection before starting Wegovy.

Switching from Wegovy to Mounjaro

To switch from Wegovy to Mounjaro, if you are a new patient with us, request Mounjaro treatment through your patient account. One of our doctors will review your eligibility, medical history, and current Wegovy dose before deciding if Mounjaro is right for you.

If you are already a patient with us at ASDA Online Doctor, you don’t need to start again. Simply complete a quick questionnaire in your account, and our doctors can check if Mounjaro is suitable for you.

If approved, you will start on the recommended starting dose of Mounjaro and gradually increase to a maintenance dose that is safe, suitable and effective for you.

Can I switch from injections to Wegovy tablets?

Yes, you can switch from injections to Wegovy tablets. The prescribing guidelines for injections and Wegovy tablets are the same, as they all contain GLP-1 medications.

If you’re currently taking Wegovy at a maintenance dose of either 2.4 or 7.2mg, you can switch by taking a 1-week break between your last injection and first Wegovy 25mg tablet. If you’re taking a different weight loss injection or a lower dose, your doctor will let you know what Wegovy tablet dose you can start on.

Weight loss test kit

Understanding what’s happening inside your body can help you reach your weight goals. Our Weight Loss Test Kit checks key health markers that can affect your weight, helping you make informed choices about your health.

This test looks at:

• cholesterol – the fats in your blood that affect heart health
• HbA1c – your average blood sugar level, linked to energy and weight changes

Why testing cholesterol and blood sugar matters

Your weight can be influenced by more than just diet and exercise. Blood sugar and cholesterol levels play a big part in how your body stores and uses energy. Checking them can highlight any issues that might make it harder to manage your weight.

HbA1c (blood sugar)

HbA1c measures the amount of sugar attached to your red blood cells.

It shows your average blood sugar level over the past few months and helps identify prediabetes or diabetes. When your body can’t use sugar properly, glucose builds up in your blood.

High HbA1c levels can mean you’re at higher risk of diabetes and can also affect your weight and energy levels.

Cholesterol (heart health)

Cholesterol is a natural fat made by your liver and found in some foods. It helps your body make vitamin D, hormones, and bile for digestion.Too much of the wrong type can be harmful. There are two main types:

• HDL (good cholesterol) – helps remove fat from your blood
• LDL (bad cholesterol) – can block your arteries and raise your risk of heart disease

Our test also checks triglycerides, another type of fat made by your liver. High levels can increase the risk of heart attack or stroke.

What your results mean

Your results show how well your body is processing sugar and fat. If your levels are outside the healthy range, our doctors can help guide you on what that means and what to do next, whether that’s changes to your diet, lifestyle, or further tests. Knowing your numbers is often the first step to making positive changes.

Alternatives to weight loss medications

Diet

Making changes to your diet is an effective way to lose weight, especially as you reduce your calorie intake. Calories are the amount of energy stored in food and drinks. If you take in more calories in a day than you use, the extra calories are stored as fat.

As a general guideline, men need around 2,500 calories a day and women need around 2,000. The amount of calories that you need will depend on the amount of activity that you do. To lose weight in a safe and manageable way, the NHS recommended following a balanced diet and reducing your calorie intake by 600 calories a day.

To find information about the number of calories in certain foods, you can check the nutrition content on the package.

Physical activity

Exercise is a great way to burn calories, improve your overall health, and increase your metabolism. You should try to do about 30 minutes a day of exercise that helps get your heart rate up, like walking, swimming or riding a bicycle. If you’d rather go for more intense forms of exercise, aim for at least 75 minutes per week. Intense exercise includes going for a run, lifting heavy weights, football, basketball or boxing.

Regular physical activity can protect you against conditions like type 2 diabetes and high blood pressure. Exercise will also improve your mood and will go a long way towards managing your mental health. Your sleep will improve and you’ll have more energy to enjoy life.

Weight loss surgery

Weight loss treatment in the UK includes the option of having weight loss surgery, known as bariatric surgery. Weight loss surgery is only appropriate if you have tried to lose weight with dieting and exercise, or if you are unable to use weight loss medication. Your doctor may discuss with you whether weight loss surgery is suitable if:

• you have tried dieting and increased exercise
• your BMI is over 40, or between 35 and 40 with a weight-related condition, such as diabetes

After weight loss surgery, you’ll need to commit to long term follow up appointments with the place you had your surgery. Weight loss surgery is a type of major surgery. You should be comfortable with making large lifestyle changes to make sure the effects of the surgery are successful. You’ll also need to take lifelong vitamin supplements as you’ll be eating less food and will be at risk of nutritional deficiencies.

There are a few different ways surgery can help you lose weight:

• gastric bypass – where the top of your stomach is connected to your small intestine to reduce how much food you can eat
• gastric band – a band is placed around your stomach to help you eat less as it makes your stomach smaller
• sleeve gastrectomy – part of your stomach is removed so you feel full much quicker and eat less overall

Each type of surgery will have its benefits and potential complications. If you decide to go for weight loss surgery, your surgeon will discuss with you the risks and benefits to help you come to an informed decision.

Frequently asked questions

Who is eligible for weight loss medication?

To be eligible for weight loss medication, you usually need to have a certain BMI. This is normally defined as a BMI over 30, or between 27 and 30 with a weight related medical condition or risk factor. You’ll also need to be over 18. Each weight loss medication has its own set of prescribing criteria. A doctor will check your medical history and current medications to make sure your chosen weight loss medication is suitable. If you request a treatment through our service, our doctors will prescribe the treatment if you’re eligible. If you’re not, they can discuss alternatives that work in a similar way.

How do weight loss injections work?

Weight loss injections work by mimicking hormones in your body responsible for hunger such as GLP-1 (Wegovy, Mounjaro, and liraglutide) and GIP (Mounjaro). They send signals to your brain when you eat that trick it into thinking you’re full, even after eating less. They also delay the emptying of your stomach, making you feel fuller for longer.

When people follow a diet and exercise plan, they often find it difficult to reduce their calorie intake or snack less because they still feel hungry. As weight loss injections reduce hunger, it’s easier to lose weight.

What weight loss treatment is best for me?

Which weight loss treatment is best for you depends on lots of things, such as personal preference, your BMI, medical history, current medications, and whether you’d rather take an injection or tablet. If you’re still not sure after reading through this page, you can speak to one of our doctors for more advice.

Are weight loss injections safe?

Yes, as long as a doctor has approved treatment for you. Weight loss injections have to undergo trials and testing to make sure they are safe before they are made available to the public. Also, the active ingredients in weight loss injections have been used to treat diabetes for years before being adapted for weight loss treatment.

How long will I need to take weight loss medication?

It varies between people. Studies of weight loss injections show weight loss over 68 to 72 weeks of treatment, depending on the medication. How long it takes for you to reach your goal weight will be affected by factors like:

• your starting weight
• which dosage you use long term
• how well you stick to your diet and exercise plan
• your own metabolism

Weight loss injections are meant for long term use and not as a method of rapid weight loss. Also, it is possible to use weight loss injections to maintain your new weight once you’ve reached your goal weight.

What happens when you stop taking weight loss medications?

When you stop taking your medication, your appetite will return to normal. This doesn’t necessarily mean you will put weight back on, although it is possible. If you stick to your diet and exercise plan even after you stop your medication, you can still keep the weight off. If you are worried about stopping all at once, it is possible to taper off your treatment. You can do this by lowering the dose before stopping completely.

When will the Wegovy pill be available in the UK?

The Wegovy pill, which is a new GLP-1 tablet containing the same active ingredient as Wegovy (semaglutide), may become available in the UK in summer 2026. Before Wegovy tablets can be offered in the UK, they must first be approved by the Medicines and Healthcare Regulatory Agency (MHRA). If the MHRA does approve them, they can then be made available for healthcare providers in the UK to offer to patients.

What GLP-1 medications are approved for weight loss in the UK?

Currently, the GLP-1 medications approved for weight loss in the UK are:

• the injections Mounjaro (tirzepatide), Wegovy (semaglutide), and Nevolat (liraglutide)
• the Wegovy pill (semaglutide)

Other GLP-1 injections and tablets are available in the UK, such as Rybelsus, but this is for type 2 diabetes and not weight loss. There are also ongoing studies into other GLP-1 tablets, but only Wegovy is currently available.