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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5mg Mounjaro Not Working — What You Need to Know
If you've been taking 5mg Mounjaro for several weeks and aren't seeing expected weight loss results, dose adjustment may be the answer. Mounjaro (tirzepatide) works differently for everyone, and finding your effective dose is part of the process. This guide explains why the initial 5mg dose might not be sufficient, how dose titration works in the UK, and what your next steps are — whether you're accessing Mounjaro 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.
Why 5mg Mounjaro Might Not Be Delivering Results
The 5mg dose of Mounjaro is a first maintenance dose, not the maximum. Clinical trials show that most people need progression to higher doses — typically 10mg or 15mg — to achieve meaningful weight loss. Several factors explain why 5mg alone may not be working for you:
- Individual variation: Mounjaro affects appetite and metabolism differently in each person. Some people respond well at 5mg, while others need higher doses for the same effect.
- Time and tolerance: Your body may have adapted to 5mg after 4+ weeks, reducing its effectiveness. Dose escalation helps maintain the effect.
- Lifestyle factors: Weight loss also depends on calorie intake and physical activity. Mounjaro works alongside these, not instead of them.
- Medical factors: Certain health conditions, medications, and metabolic differences can affect response rates.
In the SURMOUNT-1 clinical trial, average weight loss at 5mg was approximately 15% of body weight, but at the maximum 15mg dose, average loss increased to approximately 21%. This shows that higher doses typically deliver better results.
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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.
Accessing Dose Escalation in the UK — NHS vs Private
NHS route: If you're taking Mounjaro through an NHS specialist weight management service, contact your clinic to discuss lack of progress. They will assess whether you're eligible for dose escalation based on your individual response, any side effects, and clinical suitability. NHS eligibility criteria and availability vary significantly by region.
Private route: If you have a UK prescription from a private prescriber, you'll need to follow up with them directly. Many online consultation services allow follow-up appointments to review progress and request dose increases. Your prescriber will typically recommend increasing to 10mg after at least 4 weeks on 5mg, following the standard Mounjaro KwikPen titration schedule. You can use our free GLP-1 weight loss calculator to project potential results at higher doses and track your progress with our weight tracker.
- 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.
How long should I stay on 5mg Mounjaro before deciding it's not working?
NHS and private prescribers typically recommend staying on each dose for at least 4 weeks before assessing effectiveness. This allows your body to adapt fully. If you've been on 5mg for 4+ weeks with no weight loss and good tolerance, it's reasonable to discuss dose escalation with your prescriber or clinic.
What dose should I increase to if 5mg isn't working?
The standard progression is from 5mg to 7.5mg, then 10mg, then 12.5mg, with 15mg as the maximum. Each dose requires at least 4 weeks before escalation. Your prescriber will recommend the appropriate next step based on your individual response and any side effects experienced.
Can I increase my Mounjaro dose myself?
No. Dose escalation must be managed by your prescriber. If you're on the NHS, contact your specialist weight management clinic. If you're private, arrange a follow-up consultation with your prescribing provider. Never adjust doses without medical guidance.
What if Mounjaro at higher doses still doesn't work?
If you don't see progress even at higher doses after sufficient time, your prescriber may explore alternatives like Wegovy (semaglutide), which is a different GLP-1 medication with different individual response patterns. Tirzepatide works through a dual GIP + GLP-1 mechanism, whereas Wegovy uses GLP-1 alone — some people respond better to one than the other.
Are there costs associated with dose escalation on the NHS?
Mounjaro through the NHS is free — there are no additional costs for dose escalation. However, NHS access depends on meeting eligibility criteria and being referred to a tier 3 specialist weight management service. Waiting times and availability vary significantly by region. Private prescriptions always come with a cost, which may increase with higher doses.
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.