Weight Loss Injections UK 2026: Complete Guide to Mounjaro, Wegovy & Saxenda

Weight loss injections are prescription medications that mimic natural gut hormones called GLP-1 (glucagon-like peptide-1) and, in the case of Mounjaro, GIP (glucose-dependent insulinotropic polypeptide). These hormones play a key role in regulating appetite, blood sugar, and how quickly your stomach empties after eating. When you inject a GLP-1 receptor agonist, it slows gastric emptying (so you feel full for longer), reduces appetite signals in the brain, and improves insulin sensitivity. The result is a significant reduction in calorie intake without the constant hunger that undermines traditional diets. All weight loss injections available in the UK are prescription-only medicines (POM). You cannot buy them over the counter. A qualified prescriber must assess your eligibility based on your BMI, health conditions, and medical history before issuing a prescription. There are currently three main options available in the UK for weight management.

Three injectable weight loss medications are currently available through UK pharmacies:

• Mounjaro (tirzepatide) by Eli Lilly is the newest and most effective option. It is a dual GIP/GLP-1 receptor agonist, meaning it activates two hormone receptors rather than one. This dual action may explain its superior weight loss results. Injected weekly. Clinical trials showed average weight loss of 20-22% of body weight over 72 weeks. Available in doses from 2.5mg to 15mg.
• Wegovy (semaglutide 2.4mg) by Novo Nordisk is a GLP-1 receptor agonist approved specifically for weight management. Injected weekly. Clinical trials showed average weight loss of approximately 15% of body weight. It was the first obesity-specific GLP-1 to receive NICE approval for NHS use in the UK.
• Saxenda (liraglutide 3mg) by Novo Nordisk is an older GLP-1 receptor agonist. Injected daily (not weekly). Clinical trials showed average weight loss of approximately 8% of body weight. Less effective than Mounjaro or Wegovy but has the longest safety track record.

For a detailed comparison of Mounjaro vs Wegovy, see our head-to-head comparison guide. For a comparison of all three, see our best weight loss injection guide.

Private prices for weight loss injections in the UK vary significantly depending on the medication, dose, and pharmacy:

• Mounjaro: From approximately £130/month for the 2.5mg starter dose, rising to £170-320/month at the 15mg maximum dose. Prices vary by up to £100 between pharmacies for the same dose.
• Wegovy: Approximately £149-299/month depending on the dose and pharmacy. Supply has been inconsistent in the UK.
• Saxenda: Approximately £100-200/month. The cheapest option per month, but requires daily injections and produces less weight loss.

The NHS is rolling out Mounjaro and Wegovy through specialist weight management services, but access is currently limited. Most people buy these medications privately. You can check your NHS eligibility using our eligibility checker. For Mounjaro, comparing prices across pharmacies can save you £50-100 per month. Our price comparison table tracks live prices from 60+ GPhC-registered UK pharmacies.

There are three main routes to getting weight loss injections in the UK:

• Private online pharmacy (most common): Complete an online consultation where a prescriber reviews your health information, BMI, and medical history. If eligible, they issue a prescription and the medication is delivered to your door in temperature-controlled packaging. The entire process typically takes 24-72 hours.
• NHS referral: Your GP can refer you to a specialist weight management service if you meet the criteria (generally BMI 35+ or BMI 30+ with weight-related conditions). NHS availability of Mounjaro and Wegovy is expanding but remains limited in many areas.
• Private GP or weight loss clinic: Some private clinics offer face-to-face consultations and ongoing support programmes. These tend to be more expensive but may include dietary coaching and regular monitoring.

To be eligible for weight loss injections, you typically need a BMI of 30 or above, or a BMI of 27 or above with at least one weight-related health condition (such as type 2 diabetes, high blood pressure, or high cholesterol). For a step-by-step walkthrough, see our guide to getting Mounjaro in the UK. To compare pharmacy prices, visit our comparison page.

The best weight loss injection depends on your priorities:

• Mounjaro is the most effective option with the highest average weight loss. Its dual GIP/GLP-1 mechanism sets it apart. It is increasingly the most popular choice among UK patients and prescribers. Weekly injection.
• Wegovy is a strong alternative with proven effectiveness and the longest track record of NICE approval for NHS weight management. A good choice if Mounjaro is unavailable or not tolerated. Weekly injection.
• Saxenda is the most affordable per month but significantly less effective and requires daily injections. Best suited for people who want a lower-cost entry point.

Whichever medication you choose, it should be prescribed by a qualified prescriber who monitors your progress. For detailed side effects information, see our side effects guide. To plan your treatment costs, use our cost calculator. To compare current Mounjaro prices across 60+ UK pharmacies, visit our price comparison page.