Weight Loss

Weight loss treatments designed to work

Transform your weight loss journey with clinically-proven weight loss injections and tablets.

It can be hard to know where to start with your weight loss journey. That’s why our team is here to help you find the right weight loss treatment for your lifestyle.

When it comes to anti-obesity medication, you have two main options: weight loss injections or weight loss pills. Both are available from Oxford Online Pharmacy following a clinical consultation and are scientifically proven to help you lose weight when paired with an active lifestyle and balanced diet.

Browse our MHRA-approved weight loss medications in the UK below, trusted by 58,000+ weight loss patients with 34,300+ five-star Trustpilot ratings.

Compare weight loss injections in the UK

Our range of effective weight loss injections put you in control of your weight loss journey.

Easy to administer at home, these weekly injectable medications are designed for long-term weight loss management, helping you to lose weight and keep it off.

Compare weight loss tablets in the UK

Our weight loss tablets offer a needle-free alternative to support your weight loss journey.

There are several types of oral weight loss pills in the UK, and they don't all work in the same way. Some slimming tablets reduce how much fat your body absorbs from your diet, while others work as appetite control pills that reduce hunger and cravings while increasing feelings of fullness.

Use the table below to compare the different fat loss tablets available at Oxford Online Pharmacy, including how they work, how they're taken and the average weight loss seen in clinical trials.

Prescription vs over-the-counter weight loss tablets

In the UK, some weight loss tablets are available without a prescription after speaking to a pharmacist, while others are prescription-only medicines.

Making a medicine prescription-only helps ensure that a prescriber can check whether it is safe and appropriate for you.

GLP-1 pills and higher-strength Orlistat capsules are prescription weight loss drugs as they have additional risks, contraindications, interactions or monitoring requirements that need to be considered before they can be dispensed.

If you're looking for non-prescription diet pills in the UK, Alli and Orlos are the only licensed options available without a prescription. Other products sold as weight loss supplements are not the same as licensed medicines and don’t have the same evidence for their safety and effectiveness.

How do weight loss treatments work?

Weight loss treatments work in different ways depending on the class of drug they belong to and the specific active ingredients they contain.

The main ways UK-approved weight loss medications work are explained below:

Appetite suppression: Injections and GLP-1 tablets

The active ingredients in Mounjaro, Wegovy injections, and the Wegovy Pill all mimic a hormone called GLP-1, while Mounjaro also mimics a second called GIP. Activating these hormonal pathways affects areas of the brain involved in appetite regulation, helping to make you feel less hungry.

Many people also report that thoughts about food or ‘food noise’ reduces significantly while on treatment, which can help reduce how many calories you eat.

Feeling fuller for longer: Injections and GLP-1 tablets

Another way that weight loss injections work is by slowing gastric emptying, meaning they keep food in the stomach for longer. This can make you feel fuller for longer after eating and may feel more satisfied with smaller portions. As a GLP-1 medicine, the Wegovy pill also has the same effect.

It's important to remember that adopting a healthier diet and lifestyle will also play a key role in the success of your weight loss journey. Our expert team is with you at each step.

Fat absorption blockers: Orlistat, Xenical, Orlos and Alli

The way in which Orlistat works for weight loss is completely different. Orlistat, Xenical, Orlos, and Alli all block enzymes in your digestive system called lipases, which stops up to 30% of the fat you eat from being absorbed (5). The unabsorbed fat then passes out of your body in your poo.

These medicines do not affect your appetite, and although they can help put you in a calorie deficit, following a reduced-calorie, lower-fat diet is important to get the best results from treatment.

Appetite and craving control: Mysimba

Mysimba pills contain two active medicines, Naltrexone and Bupropion. They act on areas of the brain involved in controlling food intake and the reward pathways. This can help reduce appetite and food cravings, making it easier to eat less as part of a low-calorie diet.

What results can you expect from weight loss treatments?

All licensed UK weight loss medications have been studied in clinical trials, with results varying between treatments. Here are some key results:

Mounjaro weight loss results (SURMOUNT-1 and SURMOUNT-4 trials)

In the SURMOUNT-1 trial, people who reached the highest Mounjaro dose (15mg) lost on average 20-22.5% of their starting body weight over 72 weeks, and (1):

• 96% achieved 5% weight loss or more

• 90% achieved 10% or more

• 78% achieved 15% or more

• Roughly 55% achieved 20% or more

Based on these results, Mounjaro currently produces the greatest weight loss of the licensed weight loss injections available in the UK.

The SURMOUNT-4 trial was an extension study that looked at the benefits of continuing Mounjaro long-term. People who stopped treatment regained weight on average, while those who remained on treatment continued to lose weight, averaging 25% weight loss over the full 88 weeks (10).

Wegovy weight loss results (STEP 1 and STEP-UP trials)

In the STEP 1 trial, people who reached the standard 2.4mg maintenance dose of Wegovy lost an average of around 15% of their starting body weight over 68 weeks (2). The trial also found that:

• 86.4% achieved 5% weight loss or more

• 69.1% achieved 10% weight loss or more

• 50.5% achieved 15% weight loss or more

A higher 7.2mg Wegovy pen is also available for some people who need additional weight loss. In the STEP-UP trial, participants taking this higher dose lost an average of around 19-21% of their starting body weight over 72 weeks (11). This new injection for weight loss isn’t suitable for everyone but can provide additional weight loss for those who need it.

Wegovy Tablet weight loss results (OASIS 4 trial)

In the OASIS 4 trial, people taking the Wegovy Pill (25mg) lost an average of 14-17% their starting body weight after 64 weeks (9).

Other results showed how much weight you can lose on the Wegovy Pill:

• 76.3% achieved 5% weight loss or more

• 59.8% achieved 10% weight loss or more

• 47.0% achieved 15% weight loss or more

• 27.5% achieved 20% weight loss or more

These results suggest that oral Semaglutide is broadly as effective as the standard 2.4mg Wegovy injection, although the two haven’t been directly compared. There is also no equivalent to the 7.2mg injectable dose in tablet form.

Orlistat weight loss results (XENDOS trial)

In the XENDOS trial, people taking Orlistat 120mg three times daily alongside lifestyle changes were followed for four years (6). At four years:

• 31% achieved at least 5% weight loss

• 21% achieved at least 10% weight loss

• Average weight loss was 5.8kg, compared with 3.0kg with placebo

The trial showed that Orlistat can support weight loss when combined with dietary and lifestyle changes, although the average weight loss was more modest than that seen with newer GLP-1-based injections and oral tablets.

Mysimba weight loss results (COR-I and COR-II trials)

In the COR-1 trial, people taking Mysimba lost an average of 5.4% of their starting body weight, compared with 1.3% with placebo after 56 weeks (12). Other results showed that:

• 31% achieved 5% weight loss or more

• 17% achieved 10% weight loss or more

In the COR-II trial, which included a more intensive diet and behavioural programme, average weight loss was higher at 8.1% after 56 weeks, compared with 4.9% with placebo (13). This suggests how important diet and lifestyle changes are for getting the most out of your treatment.

Clinical trials show average results across thousands of participants rather than predicting how much weight one individual will lose. They indicate what is possible if treatment is taken consistently, but they are in no way a guarantee of the real-world weight loss you may see.

Your results will depend on factors such as:

• Your metabolism

• The dose you reach

• How long you stay on treatment

• The lifestyle changes you make alongside your medication

Results also take time. In the first month on a GLP-1 treatment, most people find their weight stays the same. If you’re not losing weight yet and aren’t sure how to start losing weight, the best advice is to stay consistent with your treatment, make healthy changes to your diet, and exercise regularly.

Remember, all weight loss tablets and injections support steady weight loss, and the results seen in clinical trials are after more than a year of treatment.

Additional health benefits of weight loss treatments

Weight loss treatments can offer benefits beyond weight loss itself, such as:

• Cardiovascular benefits: The SELECT trial found that Wegovy injections can reduce the risk of major cardiovascular events such as heart attack and stroke by 20% in people who were either overweight or living with obesity and had existing heart disease (3).

• Joint pain relief: Treatment with Wegovy injections in the STEP 9 clinical trial found a clinically meaningful improvement in knee osteoarthritis-related pain compared to the placebo. Physical function scores also improved among people taking Wegovy (14).

• Quality of life: Studies of both Semaglutide and Tirzepatide found improvements in physical function and quality of life alongside weight loss (15,16). In analyses of Tirzepatide, greater weight loss was associated with greater improvements in quality-of-life measures (16).

These benefits are typically greatest when weight loss treatment is combined with a healthy diet and regular physical activity. However, they are not guaranteed and may depend on the treatment you choose, your health, and how much weight loss you achieve.

Am I eligible for weight loss treatments?

Whether you qualify for weight loss treatment in the UK depends on which one you choose.

Prescription weight loss tablets and injections are typically eligible for:

• Adults aged 18-85

• People with a BMI above 30 (or a BMI above 27 and a weight-related condition such as high blood pressure or cholesterol, etc.)

• Individuals who do not have a medical condition or take medication that makes their chosen treatment unsuitable, such as type 1 diabetes for GLP-1 injections.

This list is only intended as an indicator for who might be suitable for prescription weight loss medications. Our independent doctors will complete a full medical review of your weight loss consultation to determine your individual suitability for treatment.

Over-the-counter weight loss tablets (Orlos and Alli) are typically eligible for adults aged 18 or older with a BMI of 28 or higher, following a pharmacist consultation.

Some weight loss medicines are available on the NHS, but the eligibility criteria are often different from those above used for private treatment. Availability and eligibility can vary, there are often long wait lists to access NHS weight loss drugs, and who can prescribe weight loss medications in the NHS setting depends on the specific medicine and the stage of the rollout in your area.

Speak to your GP or NHS weight management service for the most up-to-date information about the services available where you live.

Currently, you cannot get Mysimba or the Wegovy Pill on the NHS for weight management.

Who is not eligible for weight loss treatment?

Certain conditions and medicines may mean that weight loss treatments aren’t suitable for you, even if you meet the above eligibility criteria.

In general, weight loss treatments may not be considered appropriate if you:

• Are breastfeeding, pregnant or trying to get pregnant

• Have an allergy to the medicine or any other ingredients inside the injection pen or weight loss tablet.

Additionally:

GLP-1 based treatments may not be considered appropriate if you: (18-20)

• Have a history of pancreatitis

• Have a personal or family history of medullary thyroid carcinoma (MTC) or Multiple Endocrine Neoplasia syndrome type 2 (MEN2)

• Have severe gastroparesis or another condition that slows stomach emptying

• Have certain liver or kidney conditions

Orlistat-based treatments may not be considered appropriate if you: (4,7)

• Have a liver condition called cholestasis

• Are taking amiodarone, warfarin, levothyroxine, or other drugs that may interact with Orlistat

• Have chronic kidney disease or a condition that can stop the normal absorption of vitamins and minerals from the gut.

Mysimba may not be considered appropriate if you: (8)

• Have uncontrolled high blood pressure (hypertension)

• Have a history of seizures or other conditions that increase the risk of seizures

• Have severe liver or kidney problems

• Have bipolar disorder

• Are currently taking opioid medicines, including some opioid painkillers like codeine or co-codamol, or MAOI antidepressants

Our prescribers will review your medical history and current medications during your consultation to determine whether your chosen treatment can be prescribed. If they cannot safely prescribe it to you, they may recommend an alternative.

Advisory information

If you are pregnant or planning a pregnancy, weight loss medication should not be used. Some treatments need to be stopped in advance. For example, Semaglutide should be stopped at least 2 months before a planned pregnancy. Speak to your prescriber for advice before trying to conceive.

For menopausal women taking HRT, you should consider changing oral oestrogen to transdermal oestrogen and also increasing the dose of progesterone for 4 weeks after initiation of a GLP-1 or after any dose change (17). You should discuss this further with your GP or prescribing Doctor.

For women taking the contraceptive pill, some weight loss medications can affect its effectiveness. Severe diarrhoea caused by Orlistat may reduce absorption of the pill, while with Mounjaro you should use a barrier method of contraception for 4 weeks after starting and after each dose increase.

For people taking Orlistat, Xenical, Orlos or Alli, as the active ingredient blocks fat absorption, it may also reduce the absorption of fat-soluble vitamins (A, D, E and K). You should take a daily multivitamin at least 2 hours after your dose or at bedtime.

GLP-1 treatments can interact with some medicines or affect how they're absorbed. It's important to tell your prescriber if you take insulin, warfarin, epilepsy medicine, or oral medicines that need to be absorbed quickly, as you may need more frequent monitoring or doses may need to be adjusted.

If you take opioid medicines, Mysimba may not be suitable for you because it contains Naltrexone, which blocks the effects of opioids. This includes some opioid painkillers and certain cough and cold medicines. Tell your prescriber about any medicines you take before starting treatment.

How to order weight loss treatment

Buying private weight loss medications from Oxford Online Pharmacy is quick and secure.

For both prescription and over-the-counter, you will need to complete an online consultation before treatment can be dispensed. Prescription treatments are reviewed by one of our independent UK prescribers, while over-the-counter medications are assessed by a pharmacist.

Here is a more detailed breakdown of our simple three-step process:

1. Choose your preferred weight treatment. Compare our range of weight loss injections and tablets and select the treatment you’re most interested in trying. If you're unsure which one is right for you, our clinicians can help you decide.

2. Complete your online consultation. Fill in our confidential medical questionnaire with details about your health, current medications and medical history. This allows a member of our team to decide whether it's appropriate for you.

3. Review and delivery. If approved, we’ll dispense your medication from our UK pharmacies and send it via our tracked delivery service. Sometimes we may need to contact you for additional information before making a prescribing decision.

Already using weight loss medications?

If you’re already using weight loss medication but are thinking about a change, you may be able to switch to another treatment. Read our guides to switching from Mounjaro to Wegovy or switching from weight loss injections to tablets to find out more about your options.

Helpful links 

Explore a range of helpful links to aid your weight loss journey. 

• Our supportive weight loss blogs & articles 

• NHS BMI calculator 

• NHS understanding calories and eating habits 

• NHS exercise tips 

• The Eatwell guide 

• NICE body composition tips 

References 

1. Jastreboff AM, Aronne LJ, Ahmad NN, Wharton S, Connery L, Alves B, et al. Tirzepatide Once Weekly for the Treatment of Obesity. New England Journal of Medicine [Internet]. 2022 Jun 4;387(3):205–16.

2. Wilding JPH, Batterham RL, Calanna S. Once-Weekly Semaglutide in Adults with Overweight or Obesity. The New England Journal of Medicine [Internet]. 2021 Feb 10;384(11):989–1002.

3. A. Michael Lincoff, Kirstine Brown-Frandsen, Colhoun HM, Deanfield J, Emerson SS, Sille Esbjerg, et al. Semaglutide and Cardiovascular Outcomes in Obesity without Diabetes. The New England Journal of Medicine [Internet]. 2023 Nov 11;389(24).

4. Alli 60 mg hard capsules - Summary of Product Characteristics (SmPC) - (emc) | 6533 [Internet]. Medicines.org.uk. 2025.

5. NHS website. Orlistat [Internet]. nhs.uk. 2026 May.

6. Torgerson JS, Hauptman J, Boldrin MN, Sjostrom L. XENical in the Prevention of Diabetes in Obese Subjects (XENDOS) Study: A randomized study of orlistat as an adjunct to lifestyle changes for the prevention of type 2 diabetes in obese patients. Diabetes Care. 2003 Dec 23;27(1):155–61.

7. Xenical 120 mg hard capsules - Summary of Product Characteristics (SmPC) - (emc) [Internet]. www.medicines.org.uk.

8. Mysimba 8 mg/90 mg prolonged-release tablets - Summary of Product Characteristics (SmPC) - (emc) [Internet]. www.medicines.org.uk.

9. Wharton S, Ildiko Lingvay, Bogdanski P, Duque R, Jacob S, Karlsson T, et al. Oral Semaglutide at a Dose of 25 mg in Adults with Overweight or Obesity. New England Journal of Medicine. 2025 Sept 17;393(11):1077–87.

10. Aronne LJ, Sattar N, Horn DB, Bays HE, Wharton S, Lin WY, et al. Continued Treatment With Tirzepatide for Maintenance of Weight Reduction in Adults With Obesity: The SURMOUNT-4 Randomized Clinical Trial. JAMA [Internet]. 2023 Dec 11;331(1).

11. Wharton S, Freitas P, Joran Hjelmesaeth, Kabisch M, Kandler K, Ildiko Lingvay, et al. Once-weekly semaglutide 7·2 mg in adults with obesity (STEP UP): a randomised, controlled, phase 3b trial. The Lancet Diabetes & Endocrinology [Internet]. 2025 Sept 1.

12. Greenway FL, Fujioka K, Plodkowski RA, Mudaliar S, Guttadauria M, Erickson J, et al. Effect of naltrexone plus bupropion on weight loss in overweight and obese adults (COR-I): a multicentre, randomised, double-blind, placebo-controlled, phase 3 trial. The Lancet. 2010 Aug;376(9741):595–605.

13. Apovian CM, Aronne L, Rubino D, Still C, Wyatt H, Burns C, et al. A randomized, phase 3 trial of naltrexone SR/bupropion SR on weight and obesity-related risk factors (COR-II). Obesity. 2013 May;21(5):935–43.

14. Bliddal H, Bays H, Czernichow S, Uddén Hemmingsson J, Hjelmesaeth J, Hoffmann Morville T, et al. Once-Weekly Semaglutide in Persons with Obesity and Knee Osteoarthritis. New England Journal of Medicine. 2024 Oct 31;391(17):1573–83.

15. Rubino D, Bjorner JB, Naveen Rathor, Sharma AM, Lisa, Wharton S, et al. Effect of semaglutide 2.4 mg on physical functioning and weight and health-related quality of life in adults with overweight or obesity: Patient-reported outcomes from the STEP 1–4 trials. Diabetes, obesity & metabolism/Diabetes, obesity and metabolism. 2024 May 2.

16. Gudzune KA, Stefanski A, Cao D, Mojdami D, Wang F, Ahmad N, et al. Association between weight reduction achieved with tirzepatide and quality of life in adults with obesity: Results from the SURMOUNT-1 study. Diabetes Obesity and Metabolism. 2024 Nov 4.

17. England N. NHS England - Weight management injections [Internet]. England.nhs.uk. 2025.

18. Mounjaro KwikPen 10mg solution for injection in pre-filled pen - Summary of Product Characteristics (SmPC) - (emc) [Internet]. www.medicines.org.uk.

19. Wegovy 0.25 mg, FlexTouch solution for injection in pre-filled pen - Summary of Product Characteristics (SmPC) - (emc) [Internet]. www.medicines.org.uk.

20. Wegovy 25 mg tablets - Summary of Product Characteristics (SmPC) - (emc) | 102347 [Internet]. Medicines.org.uk. 2025.

21. Medicines and Healthcare products Regulatory Agency. UK first in Europe to authorise orforglipron for weight management and type 2 diabetes [Internet]. GOV.UK. 2026.

22. West S, Scragg J, Aveyard P, Oke JL, Willis L, Haffner SJP, et al. Weight regain after cessation of medication for weight management: systematic review and meta-analysis. BMJ [Internet]. 2026 Jan 7 [cited 2026 Aug 2];392.