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
Free tracker included with every download this week
Mounjaro 5 mg Pen: UK Cost and How to Access It
A Mounjaro 5 mg pen is the first maintenance dose of tirzepatide, the active ingredient in Mounjaro. It's used after the starting dose during weight management treatment. In the UK, you can access Mounjaro through the NHS or privately, and costs vary significantly depending on your route. This guide explains how much a 5 mg pen typically costs, where to get it, and what the eligibility requirements are. Understanding your options helps you make an informed decision about whether Mounjaro is right for you.
10,000+ calculations today · NHS-aligned thresholds · 100% free
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.
Mounjaro 5 mg Cost in the UK: NHS vs Private
In the UK, Mounjaro is available through two main routes: NHS specialist weight management services and private prescription through GPhC-registered online prescribers.
Private cost: A Mounjaro 5 mg pen typically costs between £140 and £200 when obtained privately, depending on the prescriber and pharmacy. Each pen contains four weekly injections (a month's supply). Monthly costs therefore range from roughly £140 to £200 for ongoing treatment at this dose.
NHS cost: If prescribed through an NHS tier 3 or tier 4 specialist weight management service, you pay standard prescription charges (currently £9.90 in England for most patients). However, NHS access to Mounjaro varies significantly by region, and waiting times can be lengthy.
Important context: The 5 mg dose is typically reached after 4 weeks on the starting dose of 2.5 mg. Treatment involves dose titration over several months, so cost varies as you increase doses.
Clinically BackedWeight Loss
No appointments. No waiting rooms. Just care — from a UK-regulated online pharmacy.
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?
NHS route: Referral from your GP to a specialist weight management service. NICE has approved tirzepatide (Mounjaro) for use within NHS services, but availability depends on your local Integrated Care Board (ICB). Some regions have significant waiting lists. Once prescribed, ongoing costs are prescription charges only.
Private route: Online consultation with a UK-licensed prescriber, typically taking 15–30 minutes. The prescriber reviews your health history, BMI, and weight-related conditions, then issues a prescription if appropriate. This is dispensed by a GPhC-registered pharmacy and delivered to your home. No waiting lists, but ongoing costs are higher. Use our GLP-1 weight loss calculator to estimate potential outcomes at different doses, and our BMI calculator to confirm your 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.
How long does each Mounjaro 5 mg pen last?
Each Mounjaro KwikPen contains four weekly doses, so one pen lasts approximately four weeks. At 5 mg per week, you'll go through one pen every month while on this dose.
Can I get Mounjaro on the NHS?
Yes, Mounjaro is NICE-approved for NHS use through tier 3 specialist weight management services. You'll need a GP referral. Availability varies by region, and waiting times can be months or longer in some areas.
What happens after I've used the 5 mg pen?
After four weeks on 5 mg, your prescriber may increase your dose to 7.5 mg if clinically appropriate. Dose increases typically happen every four weeks until you reach the maintenance dose for you.
Is the 5 mg dose suitable for everyone?
No. The 5 mg dose is the first maintenance dose after starting at 2.5 mg. Your prescriber will assess your individual response, side effects, and health goals to determine if 5 mg is appropriate for you or if adjustment is needed.
Are there other costs involved with Mounjaro treatment?
Private treatment includes the medication cost. You may also want to consider dietary support or fitness programmes, which are optional. If prescribed on the NHS, only standard prescription charges apply once you're in the system.
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.