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
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How Do You Feel on Mounjaro — UK Access & Costs
When starting Mounjaro (tirzepatide), most people experience a range of physical sensations, particularly around appetite and digestion. Understanding what to expect — and how much it costs in the UK — helps you decide if this prescription weight management injection is right for you. This guide covers how people typically feel on Mounjaro, what it costs, and your options for accessing it through the NHS or privately.
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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.
What to Expect: How People Feel on Mounjaro in the UK
Most people taking Mounjaro report reduced appetite and food cravings within the first week or two, though this varies considerably between individuals. Many describe feeling fuller after eating smaller amounts of food. In the first few days, nausea is very common — affecting over 30% of people, particularly after injections. This typically improves as your body adjusts over several weeks.
Other common early sensations include diarrhoea or constipation, stomach discomfort, and occasional fatigue. Some people experience changes in taste or mild dizziness. The dose titration schedule — starting at 2.5 mg and gradually increasing every 4 weeks to a maximum of 15 mg — is designed to help your body adjust gradually. Side effects like nausea often peak in the first 1–2 weeks at each new dose, then settle. Most people feel noticeably improved appetite suppression after 2–4 weeks, which supports the weight loss effects seen in clinical trials.
- Week 1–2: Possible nausea, reduced appetite begins
- Week 3–4: Most side effects settling, appetite suppression clearer
- Week 5+: Stronger appetite reduction, digestive side effects often ease
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.
Mounjaro Cost in the UK: NHS vs Private Access
On the NHS: Mounjaro is available free through specialist tier 3 weight management services if you meet NICE eligibility criteria (BMI ≥30, or ≥27.5 with weight-related health conditions). However, NHS access is limited — many regions have long waiting lists, and specialist services are not available everywhere. Referral is needed from your GP.
Privately in the UK: A private Mounjaro prescription costs approximately £129–£280 per month depending on dose. You access this through an online consultation with a UK-licensed prescriber, usually without a GP referral. A private prescription is dispensed by a GPhC-registered pharmacy. Private access is immediate but requires self-funding. Use our GLP-1 weight loss calculator to estimate potential weight loss at different Mounjaro doses, and the BMI calculator to check if you meet eligibility thresholds.
- 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 Mounjaro available on the NHS in the UK?
Yes, through specialist weight management services if you meet NICE criteria (BMI ≥30, or ≥27.5 with weight-related health conditions). However, availability varies by region and waiting lists can be very long. You'll need a GP referral to tier 3 services. Private access is faster but requires payment.
How much does Mounjaro cost privately in the UK?
Private Mounjaro costs approximately £129–£280 per month depending on your dose. Costs vary by provider. You access it through an online consultation with a UK prescriber and collection from a GPhC-registered pharmacy. Costs increase as you titrate to higher doses.
How long does nausea last when starting Mounjaro?
Nausea is very common in the first 1–2 weeks, but usually improves as your body adjusts. It may peak again temporarily at each dose increase. Most people find it manageable and brief. Eating smaller meals, staying hydrated, and eating ginger can help. If severe, speak to your prescriber.
Can I switch from Mounjaro to Wegovy if I don't feel right on it?
Yes, switching between GLP-1 medications is possible with prescriber guidance. While Mounjaro is a dual GIP/GLP-1 agonist and Wegovy is GLP-1 only, they work similarly. Some people tolerate one better than the other. Any switch must be managed by your prescriber — do not stop abruptly.
What's the difference between how you feel on Mounjaro vs Wegovy?
Both reduce appetite and may cause similar side effects (nausea, diarrhoea). Mounjaro's dual mechanism (GIP + GLP-1) may produce slightly different appetite effects for some people. Individual experiences vary widely — some feel better on one than the other. Clinical trials show both support weight loss when used alongside dietary changes.
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.