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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Cheapest Mounjaro 2.5mg in the UK — What You Need to Know
If you're looking for the cheapest Mounjaro 2.5mg, it's important to understand that cost varies significantly between NHS and private access routes in the UK. Mounjaro (tirzepatide) is a prescription-only weight management injection, and the starting dose of 2.5mg is used during the initial four-week treatment phase before dose escalation. This guide explains where to find affordable options and what to expect when accessing this medication in the UK.
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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.
Where to Access Affordable Mounjaro 2.5mg
Mounjaro is available through two main routes in the UK: NHS specialist services and private online prescribing. NHS access is typically free at point of use once prescribed through a tier 3 or tier 4 weight management service, though waiting lists can be several months long in many regions. Private access is available through GPhC-registered online pharmacies following a clinical assessment. Costs for the 2.5mg starting dose typically range from £129 to £180 per KwikPen (four-week supply) depending on the provider. Some private providers offer payment plans or discounts for multiple pens. To find the most competitive price, compare quotes from multiple registered UK online prescribing services. Always verify that any provider is registered with the General Pharmaceutical Council (GPhC) — this ensures safe, regulated access to your prescription.
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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.
Getting Started: Eligibility and the 2.5mg Phase
The 2.5mg dose is the mandatory starting point for all Mounjaro patients in the UK. You must remain on this dose for a minimum of four weeks before a prescriber can consider increasing to 5mg. To be eligible for Mounjaro, you need:
- BMI of 30 or above, OR BMI of 27–29.9 with weight-related health conditions (type 2 diabetes, high blood pressure, cardiovascular disease, sleep apnoea)
- South Asian, Chinese, Black African, or Black Caribbean adults may qualify at BMI 27.5 or above due to higher metabolic risk
- Age 18 or over
- Not pregnant, planning pregnancy, or breastfeeding
Whether accessing through NHS or private routes, your prescriber will assess your individual eligibility. Use our free GLP-1 weight loss calculator to estimate potential results, and check your starting BMI with our BMI calculator to confirm eligibility.
- 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.
Is Mounjaro cheaper on the NHS or private?
NHS access is free once prescribed, but involves significant waiting times (often several months). Private access costs £129–£180 per 2.5mg pen but is usually available within 1–2 weeks. NHS is cheaper financially; private is faster. Choose based on your urgency and local NHS availability.
Can I buy a single Mounjaro 2.5mg pen, or must I buy a full pack?
Most private providers sell individual KwikPens (one pen = four weekly doses). Some offer discounts when ordering multiple pens upfront. NHS prescriptions provide one pen at a time based on clinical need.
How long does the 2.5mg dose last?
One Mounjaro KwikPen contains four weekly doses, so one pen lasts exactly four weeks. At 2.5mg, you remain on this starting dose for a minimum of four weeks before your prescriber considers increasing to 5mg.
What's the difference between Mounjaro and Wegovy cost-wise?
Both are similar in private cost (£129–£200+ per month). Mounjaro is a dual GIP/GLP-1 agonist with potentially faster weight loss; Wegovy is a GLP-1 only. Your prescriber decides which is suitable. Clinical trial data showed Mounjaro may produce slightly greater average weight loss (~20% vs ~15%).
Is there a cheaper alternative to Mounjaro for weight loss in the UK?
Saxenda (liraglutide) may be cheaper and is available through some private providers, but it requires daily injections instead of weekly. Discuss all options with a registered prescriber to find what suits your health needs and budget.
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.