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 First Month: Cost, Access & What to Expect
Starting Mounjaro in your first month involves understanding both cost and access options in the UK. Whether you pursue NHS specialist services or private online prescription routes, your first month will involve the starting dose of 2.5 mg, with costs and timelines varying significantly by route. This guide explains how to access Mounjaro, realistic first-month expenses, and what happens during your initial weeks of treatment. Use our free BMI calculator to check your eligibility, and our GLP-1 weight loss calculator to understand potential outcomes.
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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.
Private Mounjaro Access and First-Month Costs in the UK
Private prescription routes are the most accessible way to start Mounjaro in the UK without NHS waiting lists. Following an online consultation with a UK-licensed prescriber, a prescription is issued if clinically appropriate. Your first month typically costs between £130–£200, depending on your dose and the private provider. This covers the initial 2.5 mg KwikPen (which contains 4 weeks of doses). Additional costs to consider include the consultation fee (often £20–£50) and ongoing repeat prescription costs for months 2–4 as you titrate upward. Each KwikPen, whether 2.5 mg or higher doses, contains four weeks' supply. Monthly costs increase as you move to higher maintenance doses — a 15 mg KwikPen (maximum dose) typically costs £200–£250 per month privately. NHS access through specialist tier 3 weight management services is free once prescribed, but involves referral from your GP and variable waiting times (often 6–18 months in many areas).
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: First Month Timeline and Clinical Assessment
The NHS route requires referral to your local specialist weight management service. Your GP assesses initial eligibility (BMI 30+ or 27+ with weight-related conditions), then refers you onward. Waiting lists vary dramatically by region — some areas have 3–6 month waits, others 18+ months. Once seen by the specialist team, assessment and prescription initiation typically follow within weeks.
The private route is faster: online consultation to prescription is often completed within 24–48 hours. A UK-licensed prescriber reviews your health information, medical history, and current medications via the online form. If approved, your prescription is sent to a GPhC-registered pharmacy and dispatched within 1–2 working days. This means your first Mounjaro injection can arrive within 3–5 days of consultation. Both routes require a prescription — Mounjaro is never available over-the-counter.
- 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 in the first month on the NHS?
Mounjaro is free on the NHS once prescribed through a specialist weight management service. However, there is no cost in your first month specifically — the medication is free at all doses. Access requires referral from your GP and assessment by a specialist team, which can take several months depending on your regional waiting list.
Can I start Mounjaro privately without waiting for the NHS?
Yes. Private online prescription services allow you to access Mounjaro without NHS referral. Following an online consultation with a UK-licensed prescriber, you can receive a prescription and have your first KwikPen dispatched within days, typically costing £130–£200 for the initial 2.5 mg dose.
What does the first-month KwikPen contain?
Your first KwikPen contains the starting dose of 2.5 mg tirzepatide. Each KwikPen holds four pre-filled doses (one per week), so your first KwikPen covers your entire first month. After week 4, you'll move to the 5 mg dose for weeks 5–8, requiring a second KwikPen.
Is tirzepatide the same as Mounjaro?
Yes. Tirzepatide is the active ingredient; Mounjaro is the brand name. When comparing Mounjaro vs Wegovy, tirzepatide (Mounjaro) uses a dual GIP and GLP-1 mechanism, whereas Wegovy (semaglutide) is a GLP-1-only agonist. Both are once-weekly injections licensed for weight management in the UK.
What eligibility criteria apply before my first month?
You're typically eligible for Mounjaro if you have a BMI of 30 kg/m² or above, or 27 kg/m² with a weight-related health condition (diabetes, high blood pressure, cardiovascular disease, or sleep apnoea). For South Asian, Black African, or Black Caribbean backgrounds, lower BMI thresholds may apply. A prescriber will assess your individual eligibility during consultation.
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.