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
Can I Buy Weight Loss Injections Online in the UK?
Yes, you can buy weight loss injections online in the UK, but only with a valid prescription from a licensed prescriber following a clinical assessment. Weight loss injections like Wegovy (semaglutide) and Mounjaro (tirzepatide) are prescription-only medicines. You cannot legally purchase them without a prescription, and any seller offering them without requiring one is operating illegally. This guide explains how to access weight loss injections safely and legally online through registered UK pharmacies.
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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 to Buy Weight Loss Injections Online Safely
Weight loss injections are available online through GPhC-registered pharmacies that work with UK-licensed prescribers. Here's the legal process:
- Online consultation: You complete a health questionnaire assessed by a UK-registered doctor or prescriber
- Clinical assessment: The prescriber reviews your BMI, medical history, and weight-related health conditions
- Prescription issued: If you're eligible, the prescriber issues a prescription to a registered pharmacy
- Medication dispensed: The pharmacy sends the injections to your home address
Common weight loss injections available online in the UK include Wegovy (semaglutide), which clinical trials showed may help participants lose an average of around 15% of body weight over 68 weeks, and Mounjaro (tirzepatide), a dual GIP and GLP-1 receptor agonist. Individual results vary significantly. You can use our free GLP-1 weight loss calculator to explore potential weight loss projections at different doses.
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.
What You Need to Know Before Buying Online
Eligibility requirements: You must meet specific criteria to be prescribed weight loss injections. Typically, you need a BMI of 30 or above, or 27–29.9 with at least one weight-related health condition such as type 2 diabetes, high blood pressure, or cardiovascular disease. For people of South Asian, Chinese, Black African, or Black Caribbean heritage, lower BMI thresholds may apply (27.5 or above).
Important warnings: Never buy weight loss injections without a prescription — this is illegal and unsafe. Avoid sellers not requiring health assessments or prescriptions. Be cautious of suspiciously cheap prices, as these often indicate counterfeit or stolen medications. Always check that the pharmacy is GPhC-registered. Use our free BMI calculator to check your eligibility before starting an online consultation.
- 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.
Is it legal to buy weight loss injections online in the UK without a prescription?
No. Weight loss injections like Wegovy and Mounjaro are prescription-only medicines in the UK. You must obtain a valid prescription from a UK-licensed prescriber following a clinical assessment. Any seller offering these medications without requiring a prescription is operating illegally.
What's the difference between Wegovy and Ozempic?
Both contain semaglutide, but Ozempic is licensed for type 2 diabetes management (doses up to 2 mg). Wegovy is the licensed weight management version, approved for weight loss in UK adults (doses up to 2.4 mg). Using Ozempic for weight loss is off-label and not recommended.
How long does an online prescription take?
Most online consultations are completed within 24–48 hours. After the prescriber issues your prescription, the pharmacy typically dispatches within 1–2 working days. Delivery usually takes 2–3 working days via Royal Mail or courier.
Can I access weight loss injections through the NHS online?
NHS access to weight loss injections is through specialist tier 3 weight management services, not standard online consultations. You need a GP referral and assessment. Availability varies significantly by region. Private online prescribing offers faster access without NHS referral.
What side effects should I expect from weight loss injections?
Common side effects include nausea, diarrhoea, constipation, and stomach pain — especially when starting or increasing doses. These typically reduce over time. Serious side effects are rare but can include severe stomach pain (possible pancreatitis) or gallbladder problems. Report any concerns to your prescriber immediately.
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.