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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Mounjaro Dose Increase — NHS and UK Prescribing Guide
If you're prescribed Mounjaro (tirzepatide) in the UK, your dose will typically increase gradually every 4 weeks until your prescriber finds the right maintenance level for you. This process, called dose titration, starts at 2.5 mg and can increase up to a maximum of 15 mg once weekly. Understanding how dose increases work, what side effects to expect, and whether you'll need adjustment can help you manage your treatment confidently. This guide covers NHS and private prescribing in the UK context.
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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 Increases Work in the UK
Mounjaro dose titration is a gradual escalation schedule designed to help your body adjust to the medication and allow your prescriber to find the optimal dose for weight management alongside diet and physical activity. You'll start at 2.5 mg once weekly (weeks 1–4), then move to 5 mg (weeks 5–8), then 7.5 mg, 10 mg, 12.5 mg, and finally 15 mg (the maximum dose). Each dose is held for a minimum of 4 weeks before increasing, unless your prescriber recommends otherwise. The KwikPen device delivers one pre-filled injection per week. If you experience significant side effects, your prescriber may keep you at your current dose longer or adjust the schedule. MHRA-approved UK guidance recommends this stepped approach to optimise tolerability and effectiveness.
- Starting dose: 2.5 mg (weeks 1–4)
- First escalation: 5 mg (weeks 5–8)
- Further increases: 7.5 mg, 10 mg, 12.5 mg, 15 mg — each held for 4+ weeks
- Maximum maintenance: 15 mg once weekly
- Adjustments: Your prescriber may pause increases if side effects are significant
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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.
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What to Expect During Dose Increases
As your Mounjaro dose increases, you may notice changes in appetite, nausea, or bowel habits. Side effects are often most prominent when starting and during dose increases, but typically improve within 1–2 weeks as your body adjusts. Common experiences include nausea (especially days 1–3 after injection), reduced appetite, or changes in taste. These effects usually decrease over time; many people find that nausea is worst at lower doses and improves at higher doses as the body acclimates. Your GP or prescriber will monitor how you're tolerating each dose and can slow escalation if needed. Track your symptoms using a progress tracker and report back at your next review—your prescriber uses this information to determine whether to continue increasing or maintain your current dose.
- 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.
Will my Mounjaro dose definitely increase every 4 weeks?
Not necessarily. Your prescriber will increase your dose every 4 weeks unless you're experiencing significant side effects, have reached an effective dose for your goals, or have medical reasons to pause escalation. The schedule is flexible based on your individual response.
What's the difference between starting dose and maintenance dose?
The starting dose (2.5 mg) is the lowest dose used to assess tolerability. Maintenance dose is the ongoing dose where you stay long-term—often 10–15 mg, depending on your response and what works best for you.
Can I stay on 5 mg Mounjaro instead of increasing further?
Yes. If 5 mg is managing your weight effectively and you're comfortable with side effects, your prescriber may recommend staying at that dose rather than escalating. The goal is to find the dose that works for you, not necessarily to reach 15 mg.
What happens if Mounjaro dose increases cause severe nausea?
Tell your prescriber immediately. They may delay the next increase, keep you at your current dose longer, or adjust your schedule. Side effects often improve over 1–2 weeks, but severe nausea should always be reported.
Is Mounjaro dose titration the same on NHS and private prescriptions?
The MHRA-approved dose schedule is the same whether prescribed via NHS specialist services or private online prescribers. Individual prescribers may adapt timing based on your tolerability, but the core titration pathway (2.5 mg → 5 mg → 7.5 mg, etc.) is standard across UK prescribing.
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