Weight loss injections are a revolutionary medical treatment increasingly used in the UK in 2025 to help individuals with obesity or overweight manage their weight more effectively. These injections work by mimicking hormones that regulate appetite and metabolism, making you feel fuller for longer and consequently reducing calorie intake. The main types of weight loss injections available in the UK include Tirzepatide (Mounjaro), Semaglutide (Wegovy), and Liraglutide (Saxenda), each differing slightly in how they work and their effectiveness.
What Are Weight Loss Injections?
Weight loss injections fall primarily into a category called GLP-1 receptor agonists, originally developed to treat type 2 diabetes. They replicate the function of glucagon-like peptide-1 (GLP-1), a natural hormone that helps control blood sugar and appetite. By activating GLP-1 receptors in the brain and pancreas, these medications slow stomach emptying and reduce feelings of hunger, helping individuals eat less without constant hunger pangs.
Tirzepatide (Mounjaro) goes a step further by also mimicking another hormone called glucose-dependent insulinotropic polypeptide (GIP), enhancing weight loss effects beyond GLP-1 alone.
The Main Weight Loss Injections in the UK (2025)
| Injection Brand | Active Ingredient | Administration | Average Weight Loss | Key Features |
| Mounjaro | Tirzepatide | Once weekly | Around 20-25% | Dual hormone action (GLP-1 & GIP), greatest average weight loss, NHS rollout in specialist clinics and some GP/community settings |
| Wegovy | Semaglutide | Once weekly | 15-17% | GLP-1 agonist, approved for weight loss, higher dose than Ozempic (diabetes drug), available on NHS through specialist referral |
| Saxenda | Liraglutide | Daily | 5-7% | GLP-1 agonist, daily injection, less weight loss on average but approved for obesity treatment |
Who Can Access These Injections?
In the UK, these injections are generally available by prescription through specialist weight management clinics, and increasingly via GPs and community clinics, depending on local services. To qualify for NHS prescriptions, strict criteria apply, typically including:
- Body Mass Index (BMI) of 40 or above (or 37.5 for some ethnic groups)
- Presence of obesity-related health conditions like type 2 diabetes, high blood pressure, or heart disease
- Commitment to accompanying lifestyle changes such as diet and exercise
These are not available over the counter and require medical supervision due to possible side effects and to ensure safety.
How Do They Work?
- Appetite Suppression: By mimicking GLP-1 (and GIP in Mounjaro), these drugs signal your brain to reduce hunger.
- Slowing Digestion: They slow gastric emptying, meaning food stays in your stomach longer, making you feel full.
- Improving Metabolism: They help regulate blood sugar and insulin, which can assist with metabolic health.
Benefits of Weight Loss Injections
- Significant and sustained weight loss compared to lifestyle changes alone.
- Improvement in obesity-related conditions like diabetes, high blood pressure, and cholesterol.
- Convenience of once-weekly (or daily for Saxenda) self-administration.
- Support alongside diet and exercise enhances long-term success.
Possible Side Effects
Common side effects include nausea, vomiting, diarrhea, constipation, and headaches. These usually improve over time with continued use. Serious side effects are rare but may include pancreatitis or gallbladder issues, so close medical follow-up is essential.
Future and Availability
NHS England plans to increase availability of these injections, with Mounjaro expected to be rolled out to hundreds of thousands of patients by the end of 2027. Access in Northern Ireland will start in 2026. Private prescription options are also available but can be costly.
Summary
Weight loss injections such as Mounjaro, Wegovy, and Saxenda represent a promising advancement in managing obesity in the UK in 2025. They help reduce appetite and facilitate major weight loss when combined with lifestyle changes, improving both physical health and quality of life. However, they require prescription, specialist oversight, and commitment to healthy behaviours to achieve lasting benefits. If you are considering weight loss injections, consult your GP or a specialist weight management clinic to discuss eligibility, benefits, risks, and the best treatment options tailored to your needs.
