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
What Is Another Name for Mounjaro?
Mounjaro's other name is tirzepatide — this is the active pharmaceutical ingredient (generic name) licensed in the UK for weight management. The brand name "Mounjaro" is used by the manufacturer Eli Lilly, but you may see it referred to as tirzepatide on prescriptions, NHS guidance, or clinical information. Understanding both names helps when researching UK prescribing information, NICE guidance, and NHS specialist services. Our GLP-1 weight loss calculator can help you explore potential weight loss outcomes with tirzepatide at different dose levels.
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.
Tirzepatide: The Generic Name and How UK Prescribing Works
Tirzepatide is the generic (scientific) name for Mounjaro. When you receive a prescription from your GP or a UK-licensed prescriber, it may be written as either "Mounjaro" or "tirzepatide" — both refer to the same medicine. The MHRA (UK medicines regulator) approved tirzepatide for weight management under the brand name Mounjaro, and it is subject to additional monitoring (Black Triangle ▼ status). NHS NICE guidance also refers to tirzepatide when discussing weight management eligibility and specialist tier 3 services. The Mounjaro KwikPen is the UK delivery device, administered as a once-weekly injection at doses ranging from 2.5 mg to 15 mg. Understanding the generic name tirzepatide is particularly useful when reading clinical trial data, NHS referral guidance, or comparing it with other weight loss options like Wegovy (semaglutide).
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 Eligibility and Prescribing Context for Tirzepatide
In the UK, tirzepatide (Mounjaro) access through the NHS is limited to specialist tier 3 weight management services — not standard GP prescribing. You typically need referral from your GP to a regional NHS specialist service, and availability varies significantly by area. 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. Private prescribing is also available through UK-licensed online prescribers following a clinical assessment. Our BMI calculator above helps determine eligibility thresholds, whilst the weight converter tool can help you check your weight in both metric and imperial measurements for NHS consultations.
- 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 tirzepatide the same as Mounjaro?
Yes. Tirzepatide is the generic (active ingredient) name, and Mounjaro is the brand name given by manufacturer Eli Lilly. They are identical medicines. Prescriptions and NHS guidance may use either name interchangeably.
What does the Black Triangle symbol mean for tirzepatide in the UK?
The Black Triangle (▼) indicates that tirzepatide is under additional MHRA monitoring for safety. This is standard for new medicines and does not mean it is unsafe — it means healthcare professionals are actively collecting safety data.
Can I get tirzepatide (Mounjaro) on the NHS in the UK?
Tirzepatide is available through NHS specialist tier 3 weight management services following referral from your GP. Availability and waiting times vary by region. Private prescribing is also available through online clinical assessments.
How does tirzepatide differ from semaglutide (Wegovy)?
Tirzepatide is a dual GIP and GLP-1 receptor agonist, whilst semaglutide (Wegovy) is a GLP-1-only agonist. Clinical trials suggest tirzepatide may produce slightly greater average weight loss, though individual results vary significantly.
What is the starting dose of tirzepatide in the UK?
The starting dose is 2.5 mg once weekly via the Mounjaro KwikPen. Your prescriber will increase the dose gradually — minimum 4 weeks at each dose level — up to a maximum of 15 mg per week, based on your response and tolerance.
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.