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Quick Comparison: Best Weight Loss Injections UK
| Brand | Active Ingredient | Frequency | Avg Weight Loss | Monthly Cost (Avg) |
|---|---|---|---|---|
| Mounjaro | Tirzepatide | Weekly injection | 15–22% | £175–£310 |
| Wegovy | Semaglutide | Weekly injection | 10–20% | £130–£250 |
| Ozempic | Semaglutide | Weekly injection | 5–10% | £130–£200 |
| Saxenda | Liraglutide | Daily injection | 5–10% | £80–£100 |
Quick take: Mounjaro leads in average results, Wegovy is the first NHS-endorsed option, Ozempic is used off-label, and Saxenda remains a daily alternative. Your best choice depends on your weight loss goals, medical history, and clinical guidance.
1. Mounjaro (Tirzepatide): The Dual-Action Injection
How Mounjaro Works
Mounjaro® (tirzepatide), developed by Eli Lilly, is currently one of the most effective GLP-1 receptor agonists available in the UK. Unlike other weight-loss drugs, it targets two hormones—GLP-1 and GIP—which makes it particularly powerful for sustainable weight loss and improved blood sugar control.
Tirzepatide works by slowing digestion, reducing food cravings, and improving insulin sensitivity. Acting on both GLP-1 and GIP pathways helps patients achieve fat reduction and better cardiovascular health. Large clinical trials, including research published in the New England Journal of Medicine, show an average weight loss of 15–22%, the highest among all currently available weight-loss injections.
Who Can Take Mounjaro?
Mounjaro is approved for adults with a body mass index (BMI) of 30 or higher, or those with a BMI of 27 or more who also have weight-related health conditions such as type 2 diabetes, high blood pressure, or high cholesterol. It is not suitable for patients who are pregnant, those with a history of pancreatitis, or individuals with certain thyroid cancers or severe gastrointestinal disease.
Dosing and Administration
Treatment begins at a low dose of 2.5 mg weekly, which is gradually increased every four weeks to a maximum maintenance dose of 15 mg. The medicine is given via a once-weekly injection pen, delivered through a pre-filled pen into the abdomen, thigh, or upper arm.
Possible Side Effects
The most common side effects are mild, including nausea, constipation, and stomach pain. In some cases, patients may experience more severe side effects such as pancreatitis, although these are rare. Patients are advised to review the Patient Information Leaflet carefully and follow their clinician’s treatment plan.
Final Thoughts on Mounjaro
In summary, Mounjaro offers some of the best weight loss results available today, but it works best when combined with a healthy diet, regular exercise, and clinical monitoring.
2. Wegovy (Semaglutide): The Tried and Tested Performer
Why Wegovy Stands Out
Wegovy® (semaglutide), from Novo Nordisk, was the first medicine in the UK licensed specifically for weight management. It remains one of the best weight-loss injections UK patients can access, supported by guidance from NHS England and the National Institute for Health and Care Excellence.
How Wegovy Works
Wegovy is a GLP-1 agonist that works by mimicking the body’s natural hormone glucagon-like peptide 1. This slows the emptying of your stomach, helping you to feel full for longer, while also acting on appetite centres in the brain to reduce food cravings. As a result, patients can manage their calorie intake more effectively, leading to meaningful weight loss when combined with a reduced-calorie diet.
Who Is Wegovy For?
This medicine is licensed for adults with a BMI of 30 or more, or for those with a BMI of 27 and additional conditions such as type 2 diabetes, high blood pressure, or high cholesterol. Wegovy is given once weekly via a pre-filled pen, with doses starting as low as 0.25 mg and gradually increasing every four weeks until the maintenance dose of 2.4 mg is reached. This slow increase helps to reduce the side effects of weight loss injections, which can include nausea, constipation, and diarrhoea. Rare but more serious risks include pancreatitis and gallbladder problems.
Effectiveness and Results
Overall, Wegovy is a well-researched and trusted option, with clinical trials demonstrating average weight loss of 10–20%. It is often the first step in a structured Weight Loss Programme and continues to be one of the most widely prescribed weight-loss medicines in the UK.
3. Ozempic (Semaglutide): The Off-Label Option
What is Ozempic?
Ozempic® (semaglutide), also developed by Novo Nordisk, is officially licensed in the UK as a diabetes medication for patients with type 2 diabetes. Its primary role is to improve blood sugar levels and reduce the risk of cardiovascular disease, but it is sometimes prescribed off-label for weight loss in private practice.
How does Ozempic work?
Like Wegovy, Ozempic works by mimicking GLP-1, regulating appetite and slowing digestion. However, its maximum licensed dose is only 1.0 mg weekly, compared with Wegovy’s 2.4 mg. This means the average weight loss achieved is typically lower, in the range of 5–10%.
Who is Ozempic suitable for?
Ozempic may be considered for adults with a BMI of 30 or more, or those with a BMI of 27 and additional weight-related conditions. It is not licensed for obesity and is not available through NHS services as a weight-loss treatment. The medicine is taken as a once-weekly injection pen, with doses increased gradually to minimise potential side effects such as nausea, constipation, and mild stomach upset.
Risks and considerations
Although serious side effects such as pancreatitis are rare, they remain a possibility, so clinical monitoring is recommended. Some patients achieve significant weight loss with Ozempic, but in most cases, Wegovy injections are the preferred choice as they are purpose-built for obesity treatment.
4. Saxenda (Liraglutide): The Daily Option
What is Saxenda?
Saxenda® (liraglutide), another treatment from Novo Nordisk, differs from other injections because it requires daily dosing. Despite the rise of weekly alternatives, Saxenda remains a valuable option in many GP practices and specialist clinics.
How does Saxenda work?
Saxenda works by mimicking the GLP-1 hormone, reducing appetite and food cravings, slowing digestion, and supporting a steady reduction in calorie intake. It is often prescribed for patients with a BMI of 30 or higher, or for those with a BMI of 27 combined with medical conditions such as type 2 diabetes, high blood pressure, or high cholesterol.
Dosage and administration
Treatment starts with a 0.6 mg daily dose, increasing weekly until the maintenance dose of 3.0 mg is reached. Injections are given using a pre-filled pen, which can be administered in the abdomen, thigh, or upper arm.
Side effects and risks
Common side effects include nausea, diarrhoea, and mild stomach upset, which usually improve with time. Rare but serious complications such as pancreatitis and gallbladder disease are possible.
Summary
Although its daily routine makes it less convenient than weekly injections, Saxenda remains an important weight loss medicine for patients who are unable to use newer options. When combined with a balanced diet, healthy eating, and a structured exercise plan, Saxenda supports reliable and clinically proven weight loss in the range of 5–10%.
Are Weight Loss Injections Safe?
All four treatments—Mounjaro, Wegovy, Ozempic, and Saxenda—are clinically tested weight-loss drugs that have undergone rigorous review in clinical trials. These studies, including those published in the New England Journal of Medicine, show that they are safe and effective when prescribed under medical supervision.
The most common side effects are digestive issues such as nausea, diarrhoea, constipation, or mild stomach pain. In most cases, these settle over time. Serious side effects are rare, but pancreatitis, gallbladder problems, or thyroid conditions may occur in certain patients. Safety also depends on an individual’s medical history and any related health conditions, including cardiovascular disease, heart disease, or high cholesterol.
In summary, weight loss injections are safe for the right patients when prescribed by a clinician and combined with lifestyle changes. They are not suitable for everyone, and a consultation with a healthcare professional is essential before starting treatment.
Lifestyle Support for Long-Term Results
Weight loss injections are not a magic solution. They deliver the best outcomes when integrated into a wider lifestyle programme that includes nutrition, movement, and mental wellbeing.
From a dietary perspective, patients should follow a balanced diet that prioritises whole foods, lean proteins, and fibre-rich carbohydrates while keeping calorie intake under control. Developing healthier eating habits and focusing on healthy eating helps ensure weight loss is sustainable.
Exercise is equally important. Regular activity, ideally 150 minutes per week with additional resistance training, supports fat loss, preserves muscle, and provides wider health benefits such as reduced risk of heart attack and improved mental wellbeing. Maintaining an active daily routine makes long-term progress more achievable.
Mental health plays a key role, too. Patients who track progress beyond the scales, improve sleep quality, and reduce stress are more likely to succeed. Access to a specialist weight management service can provide support, accountability, and long-term guidance.
How to Choose the Best Weight Loss Injection UK
There is no single “best” weight loss injection for everyone. The right treatment depends on your starting weight, weight loss goals, medical conditions, and lifestyle. For those seeking significant weight loss of 15% or more, Mounjaro currently shows the highest effectiveness. Patients who require NHS access may find that Wegovy injections are available if they meet strict eligibility criteria.
Your medical background also matters. Individuals with a history of cardiovascular disease, high blood pressure, or diabetes may be guided toward certain options, while others with gastrointestinal conditions may be advised against GLP-1 therapies. Possible risks such as hair loss, stomach pain, or injection site irritation should also be discussed with your clinician.
Finally, lifestyle fit plays a role. Patients who prefer the simplicity of a weekly injection may do best with Mounjaro, Wegovy, or Ozempic, while those who are comfortable with a daily routine may benefit from Saxenda.
Most importantly, all these treatments are available only on private prescription, unless you meet NHS requirements. Working with a clinician or Medical Director ensures you receive a treatment plan tailored to your needs, combining medicine with a healthy diet, regular exercise, and long-term lifestyle support.
