The UK's most complete GLP-1 guide
Every Question Answered. Every Side Effect Explained.
- How GLP-1 medications work
- Mounjaro vs Wegovy compared
- Injection instructions
- Side effects & solutions
- What to eat on treatment
- FAQs answered
Free tracker included with every download this week
Weight Loss Pharmacy — UK Prescription Options Explained
If you're looking for weight loss pharmacy options in the UK, prescription weight loss medication may be available to you depending on your BMI and health circumstances. Three medicines are currently licensed for weight management in the UK: Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide). These aren't available over the counter—they require a clinical assessment and prescription from a licensed healthcare professional. Access is available through both NHS specialist services and private prescribing. Understanding your eligibility and the different routes to access is the first step toward exploring whether medication could support your weight management journey alongside lifestyle changes.
10,000+ calculations today · NHS-aligned thresholds · 100% free
Calculate Your BMI Instantly
Enter your height and weight below. Supports both imperial (stone & lbs) and metric (kg). Results include NHS category, healthy weight range, and ethnicity adjustments.
What Is BMI and Why Does It Matter?
Body Mass Index (BMI) is the most widely used screening tool for assessing whether your weight falls within a healthy range. Used by the NHS, GPs, and weight management services across the UK, BMI provides a quick snapshot of your weight relative to your height. The formula is simple: your weight in kilograms divided by your height in metres squared (kg/m²).
While BMI isn't a perfect measure — it doesn't account for muscle mass, bone density, or fat distribution — it remains the standard first step in identifying potential weight-related health risks including type 2 diabetes, cardiovascular disease, high blood pressure, and certain cancers.
The NHS also recommends adjusted thresholds for people of South Asian, Chinese, or Black African heritage — a BMI of 23 or above is classified as overweight, and 27.5 as obese. Our calculator includes this adjustment as a one-click toggle.
UK-Licensed Weight Loss Medications
Three prescription medications are currently approved for weight management in the UK. Mounjaro (tirzepatide) is a once-weekly injection that acts as a dual GIP and GLP-1 receptor agonist—in clinical trials, participants lost an average of 15–21% of their body weight over 72 weeks. Wegovy (semaglutide) is also a once-weekly injection, working as a GLP-1 agonist, with clinical trials showing average weight loss of around 15% of body weight. Saxenda (liraglutide) is a daily injection with similar mechanisms to Wegovy. All three are prescription-only medicines requiring a clinical assessment before prescribing. Individual results vary significantly, and all are most effective when combined with a reduced-calorie diet and increased physical activity. Your GP or a licensed prescriber will assess whether any of these medications are suitable for your individual circumstances, considering your BMI, medical history, and other health factors.
Clinically BackedWeight Loss
No appointments. No waiting rooms. Just care — from a UK-regulated online pharmacy.
How It Works
Three simple steps to understand your weight and take action.
Enter your height and weight in our free calculator. Get your BMI, NHS category, healthy weight range, and ethnicity-adjusted thresholds instantly.
If your BMI suggests you're overweight or obese, explore our GLP-1 calculators to project potential weight loss on Mounjaro or Wegovy.
Use our progress tracker to log your weight weekly, visualise your journey with charts, and stay motivated — all stored privately in your browser.
Free Weight Loss Tools & Guides
Everything you need to understand your weight, explore medication options, and track your progress — completely free.
NHS vs Private Access to Weight Loss Medication
NHS access is available through specialist tier 3 and 4 weight management services following a GP referral, though availability varies significantly by region and waiting lists can be lengthy. Private access is available through GPhC-registered online pharmacies—a licensed prescriber conducts a clinical assessment, and if appropriate, issues a prescription dispensed by the pharmacy. Private options typically offer faster access but come at a cost (usually £129–£320+ per month depending on dose). For both routes, eligibility generally requires a BMI of 30 or above, or 27–29.9 with weight-related health conditions such as type 2 diabetes, high blood pressure, or cardiovascular disease. If you're interested in exploring prescription weight loss medication, speaking with your GP is the natural first step—they can discuss options, arrange NHS referral if appropriate, or provide information on private routes.
- Dual GIP/GLP-1 receptor agonist
- Up to 22.5% body weight loss (SURMOUNT-1)
- Weekly injection, dose escalation over 20+ weeks
- Available via private prescription in the UK
- Doses: 2.5mg → 5mg → 7.5mg → 10mg → 12.5mg → 15mg
- GLP-1 receptor agonist
- Up to 15–17% body weight loss (STEP trials)
- Weekly injection, 5-step dose escalation
- NHS & private prescription available
- Doses: 0.25mg → 0.5mg → 1mg → 1.7mg → 2.4mg
Mounjaro vs Wegovy: Head-to-Head
A side-by-side comparison of the two most popular GLP-1 weight loss medications available in the UK.
| Feature | Mounjaro | Wegovy |
|---|---|---|
| Drug class | Dual GIP/GLP-1 agonist | GLP-1 agonist |
| Active ingredient | Tirzepatide | Semaglutide |
| Avg. weight loss | 15–22.5% | 12–17% |
| Key trial | SURMOUNT-1 (2022) | STEP 1 (2021) |
| Max dose | 15 mg weekly | 2.4 mg weekly |
| Escalation period | 20–32 weeks | 16–20 weeks |
| Administration | Weekly injection (pen) | Weekly injection (pen) |
| NHS availability | Private prescription only | NHS & private |
| Approx. private cost | £150–£250/month | £150–£300/month |
| Common side effects | Nausea, diarrhoea, constipation | Nausea, vomiting, diarrhoea |
Data sourced from SURMOUNT-1 and STEP 1 clinical trials. Costs are approximate and vary by provider. Always consult a prescriber.
Am I Eligible for Weight Loss Medication?
In the UK, eligibility for GLP-1 weight loss medications like Mounjaro and Wegovy is based on your BMI and overall health profile.
- BMI of 30 or above (obese)
- Age 18 or over
- No contraindicated conditions
- Committed to lifestyle changes
- BMI of 27 or above
- Plus type 2 diabetes
- Or high blood pressure
- Or obstructive sleep apnoea
Use our BMI calculator to check whether your BMI falls within the eligible range.
How We Built These Tools
Every calculator and guide on myweightcheck is built with accuracy and transparency in mind. Our BMI calculator uses the standard WHO formula with NHS-aligned category thresholds. Our GLP-1 projections are modelled on published clinical trial data from SURMOUNT and STEP studies.
All data stays on your device. We don't require sign-ups, and we don't store your health information on any server. Your progress tracker saves data locally in your browser using localStorage, so only you can see it.
We're based in the UK and our tools are designed specifically for UK users — supporting stone & lbs by default, referencing NHS guidelines, using NICE-approved medication data, and linking to GPhC-registered pharmacies.
Frequently Asked Questions
Common questions about BMI, weight loss medications, and our free UK tools.
Who is eligible for weight loss medication in the UK?
Adults with a BMI of 30 or above are typically eligible. Those with a BMI of 27–29.9 may be eligible if they have weight-related health conditions such as type 2 diabetes, high blood pressure, sleep apnoea, or cardiovascular disease. For people of South Asian, Chinese, Black African, or Black Caribbean heritage, lower thresholds may apply. Always consult your GP for a personalised assessment.
What's the difference between Mounjaro and Wegovy?
Both are once-weekly injections, but Mounjaro (tirzepatide) works as a dual GIP and GLP-1 agonist, while Wegovy (semaglutide) is a GLP-1 agonist only. In clinical trials, Mounjaro showed slightly higher average weight loss (15–21%) compared to Wegovy (around 15%), though individual results vary considerably. Your prescriber will assess which is more suitable for you.
How long does weight loss medication take to work?
Most people begin to notice changes within the first 4 weeks, though weight loss typically becomes more noticeable after 8–12 weeks as doses are gradually increased. Maximum benefit is usually seen after 16–20 weeks of treatment. Results depend on adherence to the medication, dietary changes, and physical activity—medication works best as part of a comprehensive approach.
What's the cost of weight loss medication privately in the UK?
Private costs typically range from £129–£320+ per month depending on the medication, dose strength, and provider. Starting doses are cheaper than maintenance or higher doses. NHS access is free but involves waiting lists and regional variation in availability. Compare both options with your GP when deciding your route.
Can I use my GP practice to get weight loss medication?
Your GP can refer you to NHS specialist weight management services, which may prescribe medication—though waiting times vary by region. Not all GP practices can prescribe directly. Private online prescribing offers faster access but requires payment. Ask your GP about local NHS tier 3 services and discuss both options to find what suits your circumstances.
Ready to take control of your weight loss journey?
Start with a free BMI check, explore your GLP-1 options, or begin tracking your progress today. No sign-up. No cost. Just results.