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 5.0mg: Dose Information for UK Adults
Mounjaro 5.0mg is the first standard maintenance dose of tirzepatide prescribed in the UK. It's typically reached after four weeks on the starting dose, and is where many people find their weight management results begin to show. This guide explains the 5.0mg dose, how it fits into the full titration schedule, and what to expect at this stage of treatment.
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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.
What Is Mounjaro 5.0mg and When Do You Take It?
Mounjaro is a once-weekly injectable prescription medication containing tirzepatide, a dual GIP and GLP-1 receptor agonist. At 5.0mg, this is the first maintenance dose in the UK dosing pathway. Most patients receive the 2.5mg starting dose for the first four weeks, then escalate to 5.0mg for weeks 5–8 and beyond.
The 5.0mg dose comes in a pre-filled KwikPen, and you inject it the same way each week — usually in the stomach, thigh, or upper arm. Clinical trial data shows that patients on Mounjaro 5.0mg experience weight loss averaging around 15% of body weight over 72 weeks when combined with a reduced-calorie diet and increased physical activity, though individual results vary significantly.
Many people stay on 5.0mg as their maintenance dose if they're achieving good weight loss results and tolerating the medication well. Others escalate to higher doses (7.5mg, 10mg, or more) if their prescriber recommends it. Your prescriber will assess your progress at each stage and decide whether to keep you on 5.0mg or increase further.
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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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Side Effects and What to Expect at 5.0mg
Common side effects at the 5.0mg dose include nausea, diarrhoea, constipation, and stomach discomfort — these tend to reduce over time as your body adjusts. Most people find side effects are more pronounced when first escalating from 2.5mg to 5.0mg, but improve within 1–2 weeks as tolerance builds.
The good news is that at 5.0mg, you're often past the worst of the adjustment phase. Try our free GLP-1 weight loss calculator to estimate your potential weight loss at this dose, and use our BMI calculator to track how your progress affects your health metrics. Keep regular contact with your prescriber — they can help manage any side effects and decide if you're ready to escalate further or stay on 5.0mg long-term.
- 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 5.0mg the maximum dose?
No. 5.0mg is the first maintenance dose in the UK. The maximum dose is 15.0mg. Most people stay on 5.0mg if results are good, but your prescriber may suggest escalating to 7.5mg, 10mg, 12.5mg, or 15mg depending on your progress and tolerance.
How long do you stay on 5.0mg?
There's no fixed timeframe. If you're achieving steady weight loss and tolerating the medication well at 5.0mg, you may stay on it long-term. Your prescriber reviews your progress every 4 weeks and decides whether to escalate, maintain, or adjust based on your individual response.
What's the difference between Mounjaro 5.0mg and Wegovy at similar doses?
Mounjaro 5.0mg (tirzepatide) is a dual GIP+GLP-1 agonist, while Wegovy (semaglutide) is a GLP-1 agonist only. Clinical trials suggest Mounjaro may achieve slightly higher average weight loss, but both are effective. Individual results vary, and the best choice depends on your health profile and prescriber assessment.
Can I get Mounjaro 5.0mg on the NHS in the UK?
Mounjaro is available through NHS specialist weight management services in some areas, though access and waiting times vary significantly by region. Many people access it privately through GPhC-registered online prescribers following a clinical assessment.
What happens if 5.0mg isn't working for me?
If weight loss stalls or is slower than expected, your prescriber may recommend escalating to the next dose (7.5mg). This is assessed after at least 4 weeks on 5.0mg. Conversely, if side effects are difficult to manage, your prescriber can adjust your approach or consider alternative treatments.
Ready to take control of your weight loss journey?
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