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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Stepping Up: 2.5mg to 5mg Mounjaro Escalation
If you've been prescribed Mounjaro (tirzepatide) and are moving from your starting dose of 2.5mg to the next maintenance dose of 5mg, you may have questions about timing, side effects, and what to expect. This guide explains the dose escalation process, how your body may respond, and when you should contact your GP. MyWeightCheck provides free tools including our GLP-1 weight loss calculator to help you track your progress alongside medical supervision.
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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.
How Mounjaro Dose Escalation Works
Mounjaro uses a structured dose titration schedule designed to help your body adjust gradually to the medication. You begin at 2.5mg once weekly for 4 weeks — this is the starting dose for all patients, regardless of final target dose.
After 4 weeks on 2.5mg, if you're tolerating the medication well, you escalate to 5mg once weekly. This is typically your first maintenance dose and where many patients remain, as it delivers effective weight management results. The dose increase timing is strict: minimum 4 weeks between dose changes. Do not increase sooner, even if you feel ready.
Each Mounjaro KwikPen contains 4 weekly doses (4 weeks' supply). When you move from 2.5mg to 5mg, you'll switch to a new pen with the higher dose — you cannot use the same pen for both doses.
- Week 1–4: 2.5mg KwikPen
- Week 5 onwards: 5mg KwikPen
Clinically BackedWeight Loss
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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.
What to Expect During Escalation
Moving from 2.5mg to 5mg may bring temporary side effect changes. Nausea, diarrhoea, and constipation are most common when you increase dose — these typically settle within 1–2 weeks as your body adjusts.
Some patients experience reduced appetite changes as they escalate, meaning the medication's appetite-suppressing effect may become more noticeable. This is normal and expected. You may also notice increased satiety (feeling fuller faster), which supports reduced calorie intake when combined with a healthy diet.
If side effects are severe or persistent beyond 2 weeks at 5mg, contact your prescriber — they may recommend staying at 2.5mg longer or adjusting your approach. Do not stop Mounjaro suddenly without medical guidance, and always maintain your NHS GP in the loop alongside any private prescription.
- 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 do I stay on 2.5mg before moving to 5mg?
You remain on 2.5mg for exactly 4 weeks. After week 4, if you're tolerating it well, you escalate to 5mg. The 4-week minimum is set to allow your body to adjust and monitor for side effects. Do not increase sooner.
Will I have worse side effects when I go from 2.5mg to 5mg?
Many patients experience temporary side effect changes (nausea, diarrhoea, constipation) when escalating. These typically resolve within 1–2 weeks. Side effects usually settle as your body adapts. If severe, contact your prescriber — they can advise on managing symptoms.
Is 5mg the maximum dose I can take?
No. 5mg is typically the first maintenance dose, but Mounjaro can be escalated further to 7.5mg, 10mg, 12.5mg, and up to 15mg maximum. Each dose increase requires 4 weeks on the current dose. Your prescriber will decide if escalation beyond 5mg is appropriate for you.
Can I stay on 2.5mg permanently if side effects are too difficult at 5mg?
Yes, some patients remain on 2.5mg long-term if it's effective and well-tolerated. Weight loss efficacy is lower at 2.5mg compared to higher doses, but clinical benefits are still possible. Discuss with your prescriber about your options if escalation is not tolerable.
Do I need a new KwikPen when I move from 2.5mg to 5mg?
Yes. The 2.5mg and 5mg doses come in different KwikPen cartridges. You cannot refill or reuse a 2.5mg pen. Order your 5mg pen before your week 5 injection to avoid gaps in treatment. Your prescriber or pharmacy will handle this automatically.
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.