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 12.5mg in the UK — What You Need to Know
Mounjaro 12.5mg is a prescription-only weight management injection manufactured by Eli Lilly. In the UK, the cost varies significantly depending on whether you access it through the NHS or privately. Costs typically range from £150–£250 per month privately, though this varies by provider. If you're eligible for NHS specialist weight management services, Mounjaro may be available at no charge. This guide explains UK pricing, where to find it, and eligibility criteria so you can make an informed decision about your options.
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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.
How Much Does Mounjaro 12.5mg Cost in the UK?
Private pricing: Mounjaro 12.5mg costs between approximately £150–£250 per month through private online prescribing services in the UK, depending on the provider and whether a consultation fee applies. Each KwikPen contains 4 weekly doses, so you'll need one pen per month at a stable dose.
NHS pricing: If prescribed through NHS specialist tier 3 weight management services, Mounjaro is available free at point of care. However, NHS access is limited by availability, regional variation (through integrated care boards), and waiting lists that can stretch months or years in many areas.
What affects price: Private costs vary because different registered online pharmacies set their own pricing. Consultation fees (typically £20–£50) are sometimes separate from medication costs. Some providers offer discounts for longer-term commitments or multiple prescriptions.
The 12.5mg dose is an escalation dose — most people start at 2.5mg and titrate upward over weeks, so initial costs may be lower before reaching 12.5mg.
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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 Access to Mounjaro 12.5mg
NHS route: Referral to a tier 3 specialist weight management service by your GP is required. NICE approved tirzepatide for NHS use, but availability depends on your integrated care board and current capacity. Waiting lists are common. You must have a BMI of 30 or above, or 27–29.9 with weight-related health conditions (type 2 diabetes, hypertension, dyslipidaemia, obstructive sleep apnoea, or cardiovascular disease history).
Private route: Access through a GPhC-registered online pharmacy following an online clinical assessment with a UK-licensed prescriber. No NHS referral needed. Faster access but at personal cost. Check that any provider is properly registered with the General Pharmaceutical Council.
Use our free GLP-1 weight loss calculator to estimate potential results at 12.5mg, which can help inform your decision about pursuing treatment.
- 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 12.5mg the maximum dose?
No. 12.5mg is an escalation dose. The maximum licensed dose for Mounjaro is 15mg once weekly. Most people start at 2.5mg and increase by 2.5mg every 4 weeks until reaching their effective dose, which may be anywhere from 5mg to 15mg depending on response and tolerance.
Can I get Mounjaro 12.5mg on the NHS for free?
Potentially yes, but access is limited. NICE approved tirzepatide for NHS specialist weight management services, but regional availability varies significantly and waiting lists are common. Your GP can refer you to your local tier 3 service to check eligibility and current waiting times.
How long does one Mounjaro 12.5mg pen last?
Each KwikPen contains 4 weekly doses, so one pen lasts 4 weeks (one month). At the 12.5mg dose, you'll need one pen per month. Pens must be refrigerated before use and can be kept at room temperature for up to 30 days after first use.
What's the difference between Mounjaro and Wegovy pricing?
Both are prescription-only weight management injections available in the UK privately and through NHS specialist services. Private costs are broadly similar (£150–£250/month). Mounjaro is a dual GIP/GLP-1 agonist; Wegovy is a GLP-1 agonist only. Clinical trials showed both support weight loss — individual results vary.
Are there cheaper weight loss medication alternatives in the UK?
Saxenda (liraglutide) is another GLP-1 agonist licensed for weight management and may have different private pricing. However, all prescription weight loss medications require clinical assessment and are typically in a similar price range. Your GP can advise on all available options for your situation.
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.