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 Constipation: UK Costs and How to Access
Constipation is one of the most common side effects reported by people taking Mounjaro (tirzepatide) in the UK. While usually manageable, it's important to understand not just how to handle this side effect, but also the practical costs and access routes for getting Mounjaro prescribed. This guide covers constipation management alongside essential information about UK pricing, NHS eligibility, and private prescription options, helping you make an informed decision about whether this medication is right for you.
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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.
UK Costs and Private Access Routes for Mounjaro
In the UK, Mounjaro costs vary significantly depending on the dose and provider. Private prescription through online clinics typically ranges from approximately £129 to £320 per month, depending on which dose you're on. The starting dose (2.5 mg) tends to be cheaper than higher doses, though you'll likely escalate over several weeks. Each Mounjaro KwikPen contains four weekly injections, so monthly costs align with a four-week supply. Some providers offer bundled packages or subscription discounts. Important note: the price you pay covers the prescription assessment and the medication itself, but prices vary between GPhC-registered pharmacies. NHS access is free at point of care but involves a referral to a specialist weight management service (tier 3), which may have significant waiting lists depending on your region. The Mounjaro KwikPen is the only formulation currently available for weight management in the UK.
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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.
NHS vs Private: Which Route Is Right for You?
The NHS route requires referral from your GP to a tier 3 specialist weight management service. You must meet specific BMI criteria (typically BMI 30+ or 27+ with weight-related health conditions) and be willing to engage with lifestyle support. NHS waiting lists vary enormously by region—some areas have waits of several months or longer. There is no cost to you once approved. The private route involves an online consultation with a UK-licensed prescriber. This typically takes 24–48 hours, and if approved, your prescription is dispensed by a GPhC-registered pharmacy. Private access is faster and doesn't require NHS referral, but you pay the full cost. Both routes require a genuine clinical assessment—there are no shortcuts. Constipation management is discussed during your initial assessment, and your prescriber can advise on dietary and lifestyle strategies or over-the-counter remedies.
- 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 much does Mounjaro cost privately in the UK?
Private Mounjaro costs typically range from £129 to £320 per month depending on dose. The starting 2.5 mg dose is usually cheaper than higher doses (10–15 mg). Prices vary between GPhC-registered pharmacies, so it's worth comparing. This is the full cost you pay—there are no NHS subsidies for private prescriptions.
Is Mounjaro available on the NHS in the UK?
Yes, Mounjaro was approved by NICE for NHS use in specialist weight management services. However, access is through tier 3 specialist services only, not standard GP prescription. You need a referral from your GP and must meet BMI eligibility criteria. Waiting lists vary significantly by region.
Can constipation on Mounjaro be managed without stopping the medication?
Yes. Constipation is usually manageable through increased water intake, dietary fibre (soluble and insoluble), physical activity, and over-the-counter remedies like stool softeners or laxatives if needed. Discuss specific options with your prescriber or pharmacist. Most people find it improves as their body adjusts over weeks.
How long does it take to get Mounjaro prescribed privately in the UK?
Private online consultations typically take 24–48 hours. Once approved, your prescription is sent to a GPhC-registered pharmacy and dispensed within 1–2 working days. Total time from consultation to receiving your first KwikPen is usually 3–5 working days.
What's the difference between Mounjaro and Wegovy in terms of UK cost?
Both are available privately through similar routes at comparable price ranges (typically £129–£320/month depending on dose). Mounjaro is a dual GIP/GLP-1 agonist with a different dose titration schedule, whilst Wegovy (semaglutide) is a GLP-1 agonist only. Clinical trial data shows similar average weight loss with both. Choose based on prescriber recommendation and individual suitability following assessment.
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.