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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Understanding the 5 Mg Mounjaro Dose in the UK
The 5 mg dose is the first maintenance dose of Mounjaro (tirzepatide) prescribed in the UK after a four-week starting period. This guide explains what the 5 mg Mounjaro injection means, how it's used in NHS prescribing, and what you can expect from this dose level. Mounjaro is a prescription-only, once-weekly injectable medicine licensed for weight management in UK adults. Understanding your dose is essential when discussing treatment options with your GP or a licensed prescriber.
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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.
5 Mg Mounjaro: Dosing Schedule and Clinical Context
5 mg is Mounjaro's first escalation dose after the initial four-week starting period at 2.5 mg. The typical dosing schedule works as follows: patients begin on 2.5 mg for weeks 1–4, then increase to 5 mg for weeks 5–8. This dose can be maintained or further increased depending on individual response and tolerability.
In clinical trials, the 5 mg dose of tirzepatide demonstrated meaningful weight loss results. Patients on 5 mg typically experience appetite reduction and increased satiety, though results vary significantly between individuals. The dose is delivered via a pre-filled Mounjaro KwikPen, which contains four weekly injections. Each KwikPen is stored in the refrigerator at 2–8°C until use, then can be kept at room temperature for up to 30 days after first use.
- Injection timing: once every seven days
- Duration at this dose: minimum four weeks before escalation
- Side effects: typically nausea, diarrhoea, constipation, and reduced appetite
- Monitoring: your prescriber will assess tolerability before increasing dose
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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.
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NHS Prescribing of 5 Mg Mounjaro and Eligibility
In the UK, Mounjaro is prescribed through NHS tier 3 specialist weight management services for eligible adults. Access through the NHS typically requires a GP referral to a specialist weight management clinic, and eligibility depends on BMI and weight-related health conditions. The NICE guidance and MHRA approval support tirzepatide as a treatment option, though availability varies significantly by region and waiting times can be lengthy.
Private prescribing of the 5 mg dose is also available through registered UK prescribers following an online clinical assessment. Private access does not require NHS referral and may be faster than NHS routes. Our GLP-1 weight loss calculator can help you understand potential weight loss projections at different doses, whilst our BMI calculator allows you to check your current BMI to understand eligibility criteria.
- 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 5 mg Mounjaro a starter dose or maintenance dose?
5 mg is the first maintenance dose, not the starter dose. Patients begin on 2.5 mg for four weeks, then escalate to 5 mg. The prescriber may maintain this dose or increase it further depending on how well you tolerate it and your response to treatment.
What weight loss might I expect on 5 mg Mounjaro?
Clinical trials showed varying results, but 5 mg typically produces modest weight loss in the range of 8–15% of body weight when combined with diet and exercise. Individual results vary significantly. Your prescriber can discuss realistic expectations based on your personal circumstances.
How does the 5 mg dose compare to Wegovy?
Mounjaro's 5 mg dose is approximately equivalent to Wegovy's 0.5–1 mg dose in terms of mechanism and effect, though they are different medications. Mounjaro is a dual GIP/GLP-1 agonist whilst Wegovy is GLP-1 only. Direct comparisons depend on individual response.
Can I access 5 mg Mounjaro through the NHS in the UK?
Yes, Mounjaro is available through NHS tier 3 specialist weight management services for eligible adults. However, access requires GP referral and varies significantly by region. Private prescribing is also available without NHS referral through registered UK prescribers.
What are the common side effects at the 5 mg dose?
Very common side effects include nausea, diarrhoea, vomiting, constipation, and stomach pain. These typically reduce over time as your body adjusts. Tell your prescriber if side effects are severe or persistent, as dose adjustment may be needed.
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