What is the Best Injection for Weight Loss?

Losing weight can be a daunting, challenging process for anyone, and in today’s world, many of us are seeking faster, more effective ways to shed the pounds. Specialist medications such as Mounjaro and Wegovy have become popular choices to help with this, with a host of other treatments on the market as well.  But with so many options available how can you determine what is the best injection for weight loss for you?

In this guide, we delve into the different treatments, their effectiveness, potential side effects, and much more — so you can make the right decisions to suit your needs and lifestyle. 

What are Weight Loss Injections?

Weight loss injections are prescription medications that promote a drop in body weight by targeting specific aspects of your body’s metabolism and hunger signals. They are injected under the skin (subcutaneously) and work in various ways — such as regulating appetite, affecting metabolism, or controlling blood sugar levels.

These treatments are appetite suppressants and mimic a naturally produced hormone called glucagon-like peptide-1 (GLP-1). When you eat, your body releases GLP-1 to signal that you are full and to stop you overeating. They belong to a group of medications called GLP-1 receptor agonists.

With all weight loss medications, you will start on a low dose which slowly increases over several weeks and months (a process known as titration). You’ll follow a dosage schedule until you reach a high enough strength that’s effective for you, or the maximum maintenance dose. 
Many people begin to lose weight within a few weeks of starting treatment, making weight loss injections one of the most popular and emerging therapies. 

The Most Popular Weight Loss Injections

Some of the most commonly used and available weight loss injections in the UK include Mounjaro, Wegovy, and liraglutide (formerly Saxenda). Each works in a slightly different way, but they all help to reduce hunger and help you stay feeling fuller for longer.

The most popular weight loss injections available in the UK are:

• Mounjaro contains the active ingredient tirzepatide. It’s available in 6 doses ranging from the lowest 2.5mg to 15mg and is injected once per week.
• Wegovy contains a different active ingredient called semaglutide, the same active ingredient in Ozempic, an injection used to manage type 2 diabetes. It’s injected once a week and works by reducing hunger, increasing the sense of fullness, and slowing down the time it takes for food to leave the stomach.
• Nevolat, formerly known as Saxenda, contains the active ingredient liraglutide. It is different to Wegovy and Mounjaro because it is injected daily and it only takes 5 weeks to reach the maximum maintenance dose. 
• Ozempic contains the same active ingredient as Wegovy but it is not approved for weight loss in the UK. Instead, it is prescribed to manage very high blood glucose levels in type 2 diabetes patients. 

Weight Loss Injection Comparison Table

To get a better understanding of which weight loss injection may be best for you, we’ve put together a comparison table detailing their different active ingredients, how they work, and how often you need to inject them.

What is the Best Weight Loss Injection?

The best weight loss injection for you will depend on individual factors, like current health conditions, weight loss goals, and even cost. However, in terms of how much weight you can potentially lose, Mounjaro is associated with the greatest results, but not everyone can tolerate its active ingredient well and may choose an alternative like Wegovy. Liraglutide, on the other hand, is usually a strong choice for its proven track record and affordability.  

Weight Loss Injections: How Do They Work?

Weight loss injections work by targeting the receptors of important digestive hormones to suppress your appetite, limiting the amount you eat and reducing the desire to snack, eventually contributing to substantial weight loss. How each weight loss injection works is explained in more detail below:

Mounjaro

Mounjaro is known as a dual-agonist medication. This is because it activates both GLP-1 and glucagon-like peptide-1 (GLP-1) receptors in the body. While GLP-1 helps with appetite and satiety, GIP is involved in the regulation of glucose metabolism. Together, these effects enhance weight loss and improve insulin sensitivity, making it a particularly effective weight loss injection for people who also have type 2 diabetes.

Mounjaro

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• Approved Weight Loss Treatment
• Suitable for adults with a BMI of +30kg/m²
• Pre-filled injection pen

• Discreet delivery next working day
• Online prescription - No doctor visit

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Wegovy

The active ingredient in Wegovy, semaglutide, mimics the natural GLP-1 hormone, reducing your appetite and shortening the time it takes for food to leave the stomach. Doing so increases feelings of fullness, and reduces hunger and food cravings — leading to significant weight reduction and supporting you on your journey.

People who use Ozempic may also notice significant weight loss, because it contains the same active ingredient as Wegovy. However, there are some distinct differences between both treatments which you should be aware of.

You can learn more about Wegovy in our dedicated ‘How does Wegovy work?’ guide.

Nevolat

Like Wegovy, liraglutide is also a GLP-1 receptor agonist. By mimicking the actions of GLP-1, liraglutide reduces hunger signals and slows gastric emptying, leading to an increased feeling of fullness. Liraglutide used to be available under the brand name Saxenda, but that is no longer in production. Instead, generic liraglutide, or Nevolat injections, have been approved for weight management in people who are overweight or obese and meet specific criteria.

What is the Most Effective Weight Loss Injection?

Numerous clinical trials have been conducted to assess the effectiveness of each weight loss injection. These assessments not only give details about the potential benefits of the medication, but also their safety, tolerability, and potential side effects. Here we discuss how effective they are according to the results of the studies carried out on them.

Mounjaro Effectiveness

Mounjaro is considered one of the most effective weight loss medications on the market, and clinical trials show that it can support up to a 22.5% weight reduction at its highest dose over 72 weeks. More than 90% of people in the same trial lost at least 5% of their starting weight at this dose. However, not everyone can tolerate the highest strength, but even on a 5mg/week maintenance dose 85% of people can shift 5% of their body mass. 

How Effective is Wegovy?

Wegovy has also performed well in clinical trials, with one high profile study revealing that it is possible to lose up to 15% of your starting weight at the highest dose over 68 weeks. Compared to a placebo, more people who were given Wegovy lost at least 5% of their starting body weight (86% v 31.5%).

Wegovy

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• Approved Weight Loss treatment
• Weekly injection
• Reduces risk of heart attack & stroke

• Discreet delivery next working day
• Online prescription - No doctor visit

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Recently, the results from a first of its kind study comparing the effectiveness of Mounjaro with Wegovy, confirmed what many doctors and scientists already knew – Mounjaro is more effective than Wegovy for weight loss. The findings showed:

• The average weight loss after 72 weeks was 20% on Mounjaro and 14% on Wegovy.
• A greater reduction in waist circumference was found in the Mounjaro group, 18.4 cm compared to 13 cm in the Wegovy group.
• Weight loss of at least 10%, 15%, and 20% overall were more likely in people treated with Mounjaro.

Intrigued? Learn more about Mounjaro vs Wegovy in our comprehensive comparison guide.

Nevolat (Liraglutide) Effectiveness

Daily liraglutide injections at the highest maintenance dose have been shown to help people lose, on average 8% of their initial body weight, compared to just 2.6% on placebo. A trial comparing the effectiveness of liraglutide with Wegovy demonstrated that after 68 weeks Wegovy induced an average weight loss of almost 16% compared to 6.4% on liraglutide.

All weight loss injections deliver the best results when they are used alongside healthy lifestyle changes, such as a calorie-controlled diet and a regular exercise plan. Many people notice changes in their weight and appearance within the first few weeks to months of starting treatment, but it’s important to not get fixated on averages and other people’s journeys. You are unique and your body may respond faster, slower, or at the same time as the progress outlined in clinical trials. Find out more in our ‘Stages of Noticing Weight Loss’ guide. 

How Much Do Weight Loss Injections Cost?

The cost of weight loss injections varies depending on the medication and where it is purchased from. The tablse below outlines how much you can expect to pay when you start weight loss treatment with Prescription Doctor:

The Cost of Mounjaro at Prescription Doctor

The Cost of Wegovy at Prescription Doctor

The Cost of Nevolat at Prescription Doctor

Weight Loss Injections Price Comparison

Although the cost of Wegovy starts off lower than Mounjaro, the maintenance dose becomes more expensive in the long run (£253.99 vs £244.99). In addition, Mounjaro titrates up to a higher strength than its nearest rival.

Nevolat, meanwhile, works out cheaper than both Mounjaro and Wegovy after increasing the dosage to its maximum level. For a single dose, Nevolat is more potent when compared to Wegovy, but less than Mounjaro — however it is taken on a daily basis when the others are administered weekly. 

Common Weight Loss Injection Side Effects

One of the key determining factors for many people when it comes to choosing the best weight loss injection is the potential side effects. While they can all cause adverse effects, the severity and type can vary between individuals. It is important to consider these factors when choosing the right medication for you.

The most common side effects of weight loss injections include gastrointestinal issues, like feeling sick, being sick, diarrhoea, constipation, and stomach pain. These are especially common with Mounjaro and Wegovy as your body gets used to the active ingredients during the initial weeks of treatment. Some people also report bloating fatigue or dizziness.

Some of the common side effects are shown below:
 

Don’t be alarmed by side effects or let them put you off trying weight loss injections. Many are short-lived and only occur in the first few weeks of treatment, or very briefly as your dose increases. Some people experience no issues at all, but our clinicians are on hand to give you advice and guidance if you are worried or would like help managing them.

Which Weight Loss Injection is Right for Me?

The best weight loss injection for you depends on your individual circumstances, preferences, goals, and budget. When choosing the ideal treatment, you should consider the following:

• Cost: Mounjaro may offer the highest weight loss potential, but its cost may put some people off. Wegovy is a great choice for shifting the pounds, but its maintenance dose cost is slightly higher than Mounjaro’s. Nevolat may be the preferred option for people who would like an affordable, consistent treatment. 
• Frequency: Nevolat is injected daily which can be a downside if you have a needle phobia or are less confident injecting yourself. Mounjaro and Wegovy are injected once weekly.
• Results: Mounjaro has produced the most impressive reductions in body mass in clinical trials, followed by Wegovy, and then Nevolat.
• Suitability: These medications are not suitable for everyone, so a clinician will need to assess your medical history, current medication, and any underlying health conditions before providing a prescription. So, your preferred injection may not be right for you.  
• Side effects: All three options can cause side effects, so it is key to assess your tolerance. If you experience any that affect your quality of life or are difficult to manage, you may be advised to try an alternative.

Can I Get Weight Loss Injections on the NHS?

Yes, Wegovy and liraglutide are currently available on the NHS, but typically for people who have a body mass index (BMI) of 30 or more and other treatments haven’t been successful. Recently, it has been revealed that Mounjaro is available on the NHS as part of a phased rollout. That means it will be reserved for those who are most in need.

However, if you are looking to access weight loss injections straight away, Prescription Doctor can help. Our service is generally faster and has less stringent eligibility criteria. You can access these medications if you have a BMI of:

• 30 or above or 
• 27 to 30 with weight-related health issues like high blood pressure, diabetes, or obstructive sleep apnoea

Weight Loss Injections Success Stories

Mounjaro, Wegovy, and Nevolat (liraglutide) have produced some impressive results in both clinical trials and the real world, with many reporting feeling satisfied, less cravings, and a gradual and consistent weight loss.

Clinical trial results are just one way to find out how well these medications work, but there’s nothing better than real life weight loss injections success stories. Explore our ‘Mounjaro Before and After’ article to find out how fellow users lost a staggering 92 kg in less than two years or an amazing 9.5 kg in 5 weeks.

Interested in Wegovy before and after results? Discover how one user dropped 100 pounds in one year and another lost 24.9 kg in 5 months.

Are you ready to be the next success story? Start your weight loss consultation now. 

Alternatives to Weight Loss Injections

If weight loss injections aren’t for you, prescription tablets are available, especially if you have a fear of needles, experience side effects, or don’t like the idea of injecting yourself. At Prescription Doctor the alternatives to weight loss injections we offer include:

• orlistat: Also available under the brand name Xenical, is a fat absorption blocker that can help up to 33% of the fat you eat pass out of your body as waste. It’s available as an oral capsule, each containing 120 mg of orlistat and can help up to 60% of people lose at least 5% of their starting weight in 12 weeks.
• alli: Contains a lower 60 mg dose of orlistat and works in exactly the same way as Xenical but is available to buy online and over the counter without a prescription.
• MySimba: An appetite suppressant that contains two active ingredients, naltrexone and bupropion and is thought to regulate food intake, energy balance, and the pleasurable feelings associated with eating. It is available as a pill and can help 56% of people lose at least 10% of their body weight in one year.

Still undecided? Read our dedicated guide to help you make the right decision for you: What is the Strongest Weight Loss Prescription Pill?

Weight Loss Injections FAQs

Choosing the most effective weight loss injection to suit your needs and preferences will no doubt raise some questions, particularly around safety and eligibility. That’s why we’ve answered some of the common patient questions below. 

Are Weight Loss Injections Safe?

Yes, weight loss injections are generally considered safe for most people, providing they have been sourced from reputable companies and via a prescription from a clinician. Like all medications, these treatments have had to undergo numerous rigorous clinical trials and tests to ensure their safety for the wider population.

To ensure your safety, only buy medications from trusted sources, like Prescription Doctor. We are registered with the GPhC and only provide genuine weight loss injections. Our clinicians will provide a prescription which confirms they have assessed your suitability for treatment.  

How Old Do You Have to Be For Weight Loss Injections?

To buy any weight loss injection online you will need to be at least 18 years old. We cannot provide weight loss treatment for anyone under this age. If you are concerned about your child’s weight you should speak to your doctor for further information.

Although we do not provide weight management tools for people under the age of 18, in some circumstances, weight loss injections and other medications may be available for children on the NHS. However, you will need to check with your doctor to find out what is available in your area.

What Happens When You Stop Taking Weight Loss Injections?

If you stop your weight loss injection, it’s likely you will regain some of the body weight you’ve lost. You may also notice that your appetite returns, because you’ll no longer be getting the active ingredients, like semaglutide or tirzepatide, to suppress it.

Regaining your appetite is normal, but that’s why it is important to take steps to positively change your lifestyle while using weight loss injections. Regular exercise and following a low-calorie diet will help enhance the effects of medication and help you maintain a healthy weight when you stop it.

Prescription Doctor: The Weight Loss Injection Provider You Can Trust

Deciding what is the best injection for weight loss for you may be challenging, but choosing your provider shouldn’t be. When you buy Mounjaro, Wegovy, Nevolat, or any other weight loss treatment from Prescription Doctor, you’re in safe hands. Following a short online consultation, our qualified clinicians are available to advise you on the most appropriate steps forward.

We’re here to give advice on healthy meal plans, dosage schedules, and even how to travel with Mounjaro and other medications. Our dispensing pharmacy is registered with the General Pharmaceutical Council (GPhC) and we’ve been helping people like you since 2013 — so you can be completely confident that we’re a provider you can trust.

Are you ready to add your name to the long list of Prescription Doctor’s weight loss injections success stories? If so, start your consultation now. 

Authored By

Leanne Edermaniger

Medical Content Writer

Leanne is a science and health content writer focusing on human health and biology while utilising her solid academic background.

Published on: 03/06/2025

Reviewed By

Mohamed Imran Lakhi

MPharm - Lead Pharmacist

Imran Lakhi is the superintendent pharmacist and founder at Prescription Doctor. He has been at the core of our team.

Reviewed on: 05/06/2025