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
Is Wegovy Safe for Weight Loss in the UK?
Yes, Wegovy (semaglutide) is a safe and licensed weight loss injection when prescribed and used correctly in the UK. Like all prescription medications, it has known side effects and requires a clinical assessment before use. Wegovy is approved by UK regulators and prescribed through NHS specialist services or private prescribers following proper evaluation. Understanding how it works, who can take it, and what to expect helps you make an informed decision about whether it's right for you.
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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.
How Wegovy Works and What Safety Data Shows
Wegovy (semaglutide) is a GLP-1 receptor agonist — a type of medication that mimics a natural hormone your gut produces after eating. It signals to your brain that you're full, reduces appetite, and slows how quickly food leaves your stomach. This mechanism is well-established and has been studied extensively in clinical trials.
The STEP-1 clinical trial, which evaluated semaglutide for weight management, involved thousands of adults over 68 weeks. Results showed average weight loss of approximately 15% body weight on the maximum dose (2.4 mg), alongside diet and exercise. Participants experienced nausea and digestive changes initially, but these typically lessened over time as the body adjusted.
Key safety findings:
- No unexpected safety concerns identified in clinical trials
- Side effects are mostly gastrointestinal and manageable
- Serious side effects are rare but must be monitored
- Regular GP follow-up is recommended while taking it
Wegovy has been used safely in millions of patients worldwide since 2021, with a comprehensive safety profile documented by regulatory authorities including the MHRA (UK Medicines and Healthcare Products Regulatory Authority).
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.
Who Should Not Take Wegovy and Important Considerations
Wegovy is not suitable for everyone. You cannot take it if you're under 18, pregnant, breastfeeding, or have a personal or family history of medullary thyroid cancer or multiple endocrine neoplasia syndrome type 2 (MEN2). If you have severe gastroparesis (stomach paralysis) or certain diabetic complications, your GP may advise against it.
Before starting Wegovy, inform your prescriber about all health conditions and medications, as semaglutide may interact with diabetes medications and oral contraceptives. Women on oral contraceptives should use additional barrier contraception for 4 weeks after starting and after each dose increase, as Wegovy may reduce absorption of oral medications.
Regular monitoring is essential — you'll need check-ins with your healthcare provider to assess how you're responding, manage side effects, and adjust doses safely. Individual tolerance varies significantly.
- 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.
What are the most common side effects of Wegovy in the UK?
The most common side effects are nausea, diarrhoea, vomiting, and constipation — affecting more than 1 in 10 people. Most improve within the first few weeks as your body adjusts. Other common effects include indigestion, headache, fatigue, and injection site reactions. Serious side effects like pancreatitis are rare but require urgent medical attention if you experience severe stomach pain.
Can I get Wegovy on the NHS in the UK?
Wegovy access on the NHS is limited and varies by region. It's available through NHS tier 3 specialist weight management services for eligible adults, but waiting lists can be very long in many areas. Private prescription through a UK-licensed prescriber is available without NHS referral, though this involves a cost. Ask your GP about local NHS options first.
How does Wegovy compare to Mounjaro in terms of safety?
Both are prescription-only and have similar common side effects (nausea, digestive changes). Mounjaro (tirzepatide) is a dual GIP and GLP-1 agonist, while Wegovy (semaglutide) is a GLP-1 agonist only. Safety profiles are comparable; individual tolerability varies. Direct comparisons should be discussed with your prescriber based on your personal health history.
Is semaglutide the same as Ozempic?
Both contain semaglutide, but Ozempic is licensed for type 2 diabetes (up to 2 mg dose), while Wegovy is licensed specifically for weight management (up to 2.4 mg). Using Ozempic for weight loss is off-label. Wegovy is the approved weight management version in the UK. Always ask your prescriber which medication is appropriate for you.
What should I do if I experience serious side effects?
Seek immediate medical attention if you experience severe, persistent stomach pain (possible pancreatitis), serious allergic reactions, vision changes, or rapid heart rate. Contact your GP or go to A&E. Never stop Wegovy abruptly without medical guidance. Your prescriber needs to know about all side effects, even minor ones, to adjust your dose or support you better.
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.