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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When Should I Increase My Mounjaro Dose?
Your Mounjaro dose is increased gradually over weeks and months, not all at once. In the UK, your prescriber will follow a structured dose titration schedule, starting at 2.5 mg and increasing every 4 weeks if you're tolerating the medication well. The decision to increase depends on how you're responding, any side effects you're experiencing, and your prescriber's clinical assessment. This guide explains the timing, process, and what you need to know about dose increases on this tirzepatide injection.
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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.
How Mounjaro Dose Titration Works in the UK
Mounjaro is not started at the full dose. Instead, your prescriber follows a dose titration schedule — a gradual step-up over time. Each dose is held for a minimum of 4 weeks before increasing, allowing your body to adjust and your prescriber to assess how well the medication is working and whether you're tolerating it.
- Week 1–4: 2.5 mg once weekly (starting dose)
- Week 5–8: 5 mg once weekly (first increase)
- Week 9–12: 7.5 mg once weekly (optional escalation)
- Week 13–16: 10 mg once weekly (optional escalation)
- Week 17–20: 12.5 mg once weekly (optional escalation)
- Week 21+: 15 mg once weekly (maximum dose)
Your prescriber may keep you on a lower dose if you're achieving good results or experiencing side effects. There is no fixed endpoint — the goal is to find the dose that works best for your individual health and tolerance. Some people benefit from staying at 5 mg or 7.5 mg long-term, whilst others progress to 15 mg.
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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.
When Your Prescriber May Pause or Delay a Dose Increase
Your Mounjaro dose increase may be paused or delayed if you're experiencing significant side effects, managing well at your current dose, or have medical circumstances that require stability. Your UK prescriber will discuss this with you at your review appointment. Never increase your dose yourself — dose changes must be managed by your prescriber following clinical assessment. If you're unsure about timing, contact your prescriber or the pharmacy dispensing your KwikPen. Use our free GLP-1 weight loss calculator to track expected progress at your current dose and discuss realistic timeframes with your prescriber.
- 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.
What's the minimum time between Mounjaro dose increases?
The minimum time between doses is 4 weeks. Your prescriber will not increase your dose before 4 weeks have passed at your current dose. This allows your body adequate time to adjust to the medication and for your prescriber to assess your response and side effect profile before progressing.
Can I ask my prescriber to skip a dose level or go straight to 15 mg?
Whilst dose increases are individualised, skipping levels is not standard practice in UK prescribing. The gradual titration approach helps minimise side effects and allows your prescriber to identify the optimal dose for you. Discuss your preference with your prescriber — they may adjust the pace, but the standard pathway involves progressing through dose levels.
What if I'm having bad side effects — will my dose increase be delayed?
Yes, very likely. If you're experiencing significant side effects like severe nausea or vomiting, your prescriber may delay your dose increase, keep you at your current dose longer, or in some cases recommend staying at a lower maintenance dose long-term. Side effect management is a priority in UK prescribing practice.
How does Mounjaro dose titration compare to Wegovy dose titration?
Mounjaro and Wegovy follow different titration schedules. Mounjaro starts at 2.5 mg and increases by 2.5 mg every 4 weeks. Wegovy starts at 0.25 mg and increases more gradually, reaching 2.4 mg over several months. Mounjaro reaches maximum dose faster, but both follow individualised, gradual approaches based on your response.
What if I miss a week — does my dose increase schedule change?
If you miss a dose, your prescriber's guidance is to skip it and take your next dose on your normal scheduled day. This should not affect your dose increase schedule, though you should inform your prescriber at your next review. Consistency is important for the medication to work effectively.
Ready to take control of your weight loss journey?
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