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
Can You Increase Mounjaro Dose After 2 Weeks?
No — you cannot increase your Mounjaro dose after just 2 weeks. The standard UK prescribing guidance requires a minimum of 4 weeks on each dose before escalation. This gives your body time to adjust to tirzepatide and allows your prescriber to assess how well you're tolerating the medication. If you're experiencing side effects or have questions about your dose schedule, speak to your GP or the prescriber managing your treatment.
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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.
Mounjaro Dose Titration Schedule in the UK
Mounjaro (tirzepatide) follows a strict dose escalation schedule designed to minimise nausea and other gastrointestinal side effects. You must spend at least 4 weeks on each dose before increasing to the next level. The standard UK titration is: Week 1–4: 2.5 mg; Week 5–8: 5 mg; Week 9–12: 7.5 mg; Week 13–16: 10 mg; Week 17–20: 12.5 mg; Week 21+: 15 mg (maximum). Each dose is administered once weekly via the pre-filled KwikPen device. Your prescriber may extend the time at each dose if side effects are significant or if your weight loss response is satisfactory. Increasing too quickly can trigger severe nausea, vomiting, or diarrhoea. This is why the 4-week minimum per dose is non-negotiable in clinical practice.
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 vs Private Access and Cost Considerations
In the UK, you can access Mounjaro through two routes: NHS specialist services or private prescription. NHS access is through tier 3 weight management services following GP referral, though availability and waiting times vary significantly by region. Private access is available online following a clinical assessment with a UK-licensed prescriber. Private costs typically range from £129–£320 per month depending on your dose and provider. The KwikPen device contains 4 weekly doses, so you'll need a new pen monthly. Your prescriber will discuss the dose escalation timeline and cost before starting treatment. Always ensure any prescriber you work with is UK-licensed and registered with the General Pharmaceutical Council (GPhC).
- 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.
Why is there a 4-week minimum between Mounjaro dose increases?
The 4-week minimum allows your body to adjust to tirzepatide and lets your prescriber assess tolerability and weight loss response. Rapid dose escalation significantly increases the risk of severe nausea, vomiting, and digestive side effects. It also gives time to see how well the current dose is working for you.
What happens if I experience severe side effects during dose titration?
Contact your prescriber immediately. They may extend your time at the current dose, reduce the dose, or switch you to a different medication. Never stop Mounjaro abruptly without medical guidance. Side effects often improve after a few weeks at each dose level.
Can my prescriber skip doses during titration (e.g., go from 5 mg straight to 10 mg)?
Theoretically possible but uncommon in UK practice. Your prescriber may do this if you've already tolerated a lower dose very well, but standard guidance recommends stepping through each dose level. This decision is individualised based on your health and response.
How much does Mounjaro cost privately in the UK?
Private costs typically range from £129–£320 per month (per KwikPen containing 4 weekly doses) depending on your dose and the provider. Higher doses cost more. NHS access is free but requires specialist service referral. Always check current pricing with your chosen provider.
What's the difference between Mounjaro and Wegovy regarding dose timing?
Both require 4 weeks minimum between dose increases. Wegovy has a slower titration schedule (starting at 0.25 mg, reaching 2.4 mg over 16+ weeks) while Mounjaro starts at 2.5 mg. Mounjaro is a dual GIP/GLP-1 agonist; Wegovy is GLP-1 only. Both follow prescriber-led dose escalation timelines.
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.