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
Mounjaro Patient Information for UK Adults
Mounjaro (tirzepatide) is a prescription-only weight management injection now available through NHS specialist services and private prescribing in the UK. This guide covers everything you need to know as a patient: how the medication works, UK eligibility criteria, NHS access routes, dose information, expected outcomes from clinical trials, and what to expect when taking it. Whether you're considering Mounjaro through the NHS or privately, understanding the facts will help you have an informed conversation with your GP or prescriber.
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.
NHS Eligibility and Access Routes for Mounjaro in the UK
NHS eligibility for Mounjaro: You may qualify for tirzepatide through NHS specialist tier 3 weight management services if you have a BMI of 30 kg/m² or above, or a BMI of 27–29.9 kg/m² with at least one weight-related health condition (such as type 2 diabetes, prediabetes, high blood pressure, or cardiovascular disease). For South Asian, Chinese, Black African, or Black Caribbean adults, lower BMI thresholds may apply due to higher health risks at lower weights.
How to access NHS Mounjaro: Ask your GP for a referral to your local tier 3 specialist weight management service. Availability and waiting times vary significantly across UK regions. Your BMI calculator can help you determine which category you fall into. The prescribing decision is made by the specialist team following assessment, not by your GP alone. Some areas have longer waiting lists than others—contact your local integrated care board (ICB) for information on availability in your region.
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.
Private Access, Doses, and What to Expect with Mounjaro
Private Mounjaro access: If NHS waiting times are too long, Mounjaro is available privately through GPhC-registered online pharmacies following a clinical consultation with a UK-licensed prescriber. Private access is faster and doesn't require an NHS referral. Costs typically range from £150–£320 per month depending on dose.
Dose titration: Treatment starts at 2.5 mg weekly for 4 weeks, then escalates by 2.5 mg every 4 weeks to a maximum of 15 mg. Each increase allows your body to adjust and minimises nausea. Mounjaro is a kwikpen (pre-filled injection device) you use once weekly at home—you inject into your stomach, thigh, or upper arm and rotate sites weekly.
Expected results: Clinical SURMOUNT trials showed average weight loss of 15–21% of body weight over 72 weeks on the highest dose, alongside a reduced-calorie diet and increased physical activity. Individual results vary significantly—some lose more, some less.
- 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 is Mounjaro and how does it work?
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist—it activates two natural hormone pathways that regulate appetite and blood sugar. It signals your brain that you're full, reduces food cravings, slows stomach emptying, and helps your body use fat more efficiently. It's not insulin and works differently from other weight loss medications like Wegovy.
Am I eligible for Mounjaro on the NHS?
You may qualify if you have a BMI of 30 or above, or 27–29.9 with weight-related health conditions like type 2 diabetes, high blood pressure, or cardiovascular disease. South Asian, Chinese, Black African, or Black Caribbean adults may qualify at lower BMI thresholds. Ask your GP for a referral to your local tier 3 weight management service to check eligibility.
How long does it take to see weight loss results with Mounjaro?
Most people start noticing changes in appetite within the first 2–4 weeks, but significant weight loss typically takes 8–12 weeks as your dose gradually increases. Clinical trials measured results over 72 weeks. Weight loss is gradual and works best alongside a reduced-calorie diet and increased physical activity—medications support these changes, not replace them.
What are the common side effects of Mounjaro?
Nausea, diarrhoea, constipation, and stomach pain are most common, especially when starting or increasing doses. These usually improve over 2–4 weeks. Inject slowly and eat small, low-fat meals to minimise nausea. Serious side effects are rare but include severe stomach pain (possible pancreatitis) and gallbladder problems—seek urgent medical attention if these occur.
Can I use Mounjaro if I'm taking other medications?
Mounjaro may reduce the absorption of oral medications, particularly oral contraceptives. If you take the combined pill, use additional contraception for 4 weeks after starting and 4 weeks after each dose increase. Always inform your prescriber of all medications and supplements. Some diabetes medications may need dose adjustments—your prescriber will monitor this.
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.