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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Mounjaro 5mg Reviews — UK Dose Guide
Mounjaro 5mg is the first maintenance dose of tirzepatide, stepping up from the 2.5mg starting dose. This page covers what real users and clinical data tell us about the 5mg dose — including weight loss expectations, side effects, and whether it's typically a long-term dose. If you're considering Mounjaro or already using the 5mg pen, this guide explains what the evidence shows and helps you understand what to realistically expect from this stage of treatment in the UK.
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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 the Clinical Evidence Shows About Mounjaro 5mg
Mounjaro 5mg is a stepping-stone dose in the tirzepatide journey — it's where most people first experience meaningful weight loss effects. In the SURMOUNT-1 clinical trial, participants on 5mg showed an average weight loss of approximately 15% of body weight over 72 weeks, although individual results varied significantly.
At 5mg, users typically report:
- Noticeable reduction in appetite and food cravings
- Feeling fuller after smaller meals
- Initial nausea (very common in the first 2–4 weeks, often settling after)
- Mild to moderate digestive changes
- Weight loss beginning to show after 4–6 weeks
However, 5mg is often not the final maintenance dose — many prescribers continue to escalate to 10mg or 15mg to achieve better results. Whether you stay on 5mg long-term depends on your individual response, tolerability, and clinical assessment by your prescriber.
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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.
5mg Side Effects and What Users Report
The most commonly reported side effect at 5mg is nausea — this affects more than 1 in 10 users in the first few weeks. Diarrhoea, constipation, and abdominal discomfort are also very common, though they often improve after 4–6 weeks as the body adjusts.
Less common but worth knowing: headache, fatigue, and injection site reactions. Serious side effects are rare but can include severe abdominal pain (seek urgent medical attention) and gallbladder problems.
Important: These side effects are temporary for most people. Starting at 2.5mg and gradually escalating (stepping up to 5mg) is specifically designed to help your body adapt. If you experience persistent problems at 5mg, your prescriber may slow the escalation or adjust your approach.
- 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 5mg Mounjaro enough for weight loss, or will I need to go higher?
5mg shows good results in clinical trials (average ~clinically studied weight loss), but many people escalate to 10mg or 15mg for better outcomes. Your prescriber will assess your individual response after 4 weeks on 5mg and may recommend continuing, staying, or increasing the dose based on your weight loss, side effects, and health goals.
How long does it take to see results on Mounjaro 5mg?
Most people start noticing appetite changes within 1–2 weeks. Visible weight loss typically appears after 4–6 weeks. Clinical trials measured results over 72 weeks, so patience and consistency matter. Use our GLP-1 weight loss calculator to project realistic timelines for your dose.
What's the difference between Mounjaro 5mg and Wegovy?
Mounjaro contains tirzepatide (a dual GIP + GLP-1 agonist), while Wegovy contains semaglutide (GLP-1 only). Mounjaro's dual mechanism means the starting and maintenance doses are lower — 5mg Mounjaro is roughly equivalent to 1.7mg Wegovy in terms of potency. Clinical trials show slightly stronger results with Mounjaro at equivalent strengths.
Can I stay on Mounjaro 5mg long-term, or is it just a stepping stone?
5mg is often a stepping-stone dose, but some people achieve their weight loss goals and maintain good results on 5mg alone. This depends on your individual response, tolerability, and how much weight loss you've achieved. Your prescriber will advise whether escalation or maintenance makes sense for you.
How do I access Mounjaro 5mg in the UK?
Mounjaro is prescription-only and requires a clinical assessment. You can access it through NHS specialist tier 3 weight management services (with a GP referral, though waiting lists vary) or through a private online prescriber assessment. You must meet eligibility criteria (BMI 30+ or 27+ with weight-related health conditions). Your prescriber will start you on 2.5mg and step up to 5mg after 4 weeks if appropriate.
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.