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
7.5mg Mounjaro Side Effects — What to Expect in the UK
The 7.5mg dose of Mounjaro (tirzepatide) is typically an escalation dose, used after 2–4 weeks on 5mg. At this dose, side effects are common but usually temporary. Most people experience nausea, diarrhoea, or constipation during the first few weeks, though these often settle as the body adjusts. This guide explains what side effects to expect at 7.5mg, how much Mounjaro costs in the UK, and your options for accessing this prescription-only weight loss injection through NHS or private prescription routes.
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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.
Common Side Effects at 7.5mg — What the Evidence Shows
At the 7.5mg dose, Mounjaro users typically experience the same side effect profile as lower doses, but intensity may increase slightly due to higher hormone stimulation. Very common side effects (affecting more than 1 in 10 people) include nausea, diarrhoea, vomiting, constipation, and abdominal pain. Common side effects (up to 1 in 10 people) include indigestion, acid reflux, injection site reactions, fatigue, dizziness, and hair loss. Most nausea peaks in the first 1–2 weeks after each dose increase, then gradually resolves. Gastrointestinal effects like diarrhoea or constipation typically persist longer but often become manageable with dietary adjustments. Staying hydrated and eating smaller, frequent meals can help reduce symptoms. If side effects are severe or persistent, always contact your GP or the prescriber who issued your Mounjaro prescription — dose adjustment or switching medication may be appropriate.
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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 Routes
Private prescription cost: A 7.5mg Mounjaro injection typically costs £150–£200 per weekly dose through private UK prescribers, or approximately £600–£800 per month (4 pens per KwikPen pack). Prices vary depending on the prescriber and pharmacy. NHS access: Mounjaro is available on the NHS through specialist tier 3 weight management services, but access is limited and varies significantly by region. Referral from your GP is typically required. Waiting times for NHS specialist services can be several months to years in many areas. How to access privately: Complete an online health questionnaire with a UK-registered prescriber, provide your medical history, and if approved, receive a prescription dispensed by a GPhC-registered pharmacy. The entire process usually takes 24–48 hours. Check your personal BMI using our free BMI calculator to determine if you meet eligibility criteria before applying.
- 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.
Are side effects worse at 7.5mg Mounjaro than at 5mg?
Not necessarily worse, but intensity may increase slightly with the higher dose. Most people experience the same side effect types (nausea, diarrhoea) but these often settle within 1–2 weeks as the body adapts. Individual responses vary significantly. If side effects are unbearable, speak to your prescriber about staying on 5mg longer.
How much does 7.5mg Mounjaro cost privately in the UK?
A single 7.5mg injection costs approximately £150–£200 privately. Since you inject once weekly, one month costs around £600–£800. Private costs vary by prescriber and pharmacy — no specific pharmacy names are recommended, but GPhC-registered pharmacies offer regulated, safe service.
Can I get Mounjaro on the NHS at 7.5mg?
Yes, Mounjaro is NHS-approved for weight management through specialist tier 3 services. However, access is limited and varies by region. You'll need a GP referral and an assessment by the specialist service. Waiting lists can be lengthy — private prescription may be quicker if cost is feasible.
What's the difference between Mounjaro and Wegovy side effects?
Both are GLP-1-based weight loss injections with similar side effect profiles (nausea, diarrhoea, constipation). Mounjaro is a dual GIP+GLP-1 agonist, while Wegovy is GLP-1 only. Clinical trial data suggests slightly different weight loss patterns, but side effects are comparable. Your prescriber can advise which suits you.
Should I stop Mounjaro if side effects are severe?
Do not stop without medical guidance. Contact your GP or prescriber immediately if you experience severe, persistent side effects. They may recommend staying on your current dose longer, slowing dose escalation, or switching to an alternative medication. Serious side effects like severe stomach pain require urgent medical attention.
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.