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
When and How to Reduce Your Mounjaro Dose
If you're taking Mounjaro (tirzepatide) and experiencing side effects or want to adjust your dose, it's important to do this safely under medical supervision. Reducing your Mounjaro dose is a decision that should always be made with your prescriber — whether through the NHS or private prescription route. This guide explains the UK approach to dose reduction, when it might be appropriate, and what to expect during the process.
10,000+ calculations today · NHS-aligned thresholds · 100% free
Calculate Your BMI Instantly
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.
Understanding Mounjaro Dose Reduction in UK Practice
Mounjaro is typically started at 2.5mg and increased gradually over weeks to reach an effective maintenance dose (5mg to 15mg). Dose reduction isn't standard in the SURMOUNT clinical trials, but prescribers in UK practice do occasionally reduce doses if side effects become problematic or other health changes occur.
Common reasons for dose reduction include:
- Persistent nausea or diarrhoea affecting daily life
- Development of new health concerns requiring prescriber review
- Changes in kidney function or other medical conditions
- Patient choice after discussing risks and benefits with their GP or prescriber
- Adjustment during treatment if side effects don't settle at a higher dose
Any dose change should be managed by your prescriber, not adjusted on your own. Stopping Mounjaro suddenly or skipping doses without guidance can affect your weight management progress and may cause other complications.
Clinically BackedWeight Loss
No appointments. No waiting rooms. Just care — from a UK-regulated online pharmacy.
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.
NHS Route vs Private Prescription Guidance
If you're receiving Mounjaro through an NHS tier 3 specialist weight management service, dose reduction discussions must go through your NHS specialist team. They will assess your side effects, review your health status, and decide whether stepping down a dose is appropriate.
If you're prescribed Mounjaro through a private online prescriber, contact them directly if you're struggling with side effects. Many private prescribers offer follow-up consultations to adjust your dose. Never stop or reduce your dose without speaking to your prescriber first — they need to know why you want to reduce and can advise on the safest way forward for your individual situation.
- 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.
Can I reduce my Mounjaro dose if I'm having side effects?
Yes, dose reduction is possible if side effects are troublesome, but this must be discussed with your prescriber first. Your GP or specialist will assess your symptoms, review how long you've been on your current dose (side effects often improve after 4–8 weeks), and decide if stepping down is the right option. Never reduce your dose without professional guidance.
What happens if I reduce my Mounjaro dose?
Reducing your dose may lead to fewer side effects, but it may also affect weight loss results. Your prescriber will help you weigh these factors. Some people find a lower effective dose that balances side effect management with weight loss benefit. Results vary, and your progress tracker can help you monitor weight stability at any dose level.
How long should I wait on a dose before considering reduction?
Most prescribers recommend staying on each Mounjaro dose for at least 4 weeks before increasing — and this principle applies to reduction too. Many gastrointestinal side effects settle down after a few weeks as your body adapts. Your prescriber may recommend waiting 4–8 weeks at your current dose before reducing, to see if symptoms improve naturally.
Is dose reduction common in NHS weight management services?
Dose reduction isn't the standard approach in NHS specialist services, where the goal is to reach an effective therapeutic dose. However, if side effects are significantly affecting your quality of life or new health concerns arise, your NHS specialist team can review your case and adjust if clinically appropriate. NICE-approved pathways focus on safety and individual tolerance.
What should I do if I want to reduce my dose but my prescriber disagrees?
If you're struggling with side effects or have concerns, explain this clearly to your prescriber. Ask them to explain their reasoning and whether waiting longer might help. You have the right to discuss your treatment, but stopping or reducing without medical input could affect your health and weight management plan. A good prescriber will listen and work with you to find a solution.
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.