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
Can You Take Mounjaro for Just One Month in the UK?
Short-term Mounjaro use is not typically how this medication is prescribed in the UK. Mounjaro (tirzepatide) is designed as a longer-term weight management treatment, with clinical trials running 72 weeks or more. The dose titration schedule requires a minimum of 4 weeks at each dose level before escalation, meaning meaningful results take time. If you're interested in exploring prescription weight loss options, your GP or a licensed prescriber can assess your individual situation and discuss realistic timescales and what to expect from treatment.
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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.
How Mounjaro Prescription Access Works in the UK
Mounjaro is a prescription-only medicine available in the UK through two main routes. Through the NHS, tirzepatide is accessed via specialist tier 3 weight management services — typically following GP referral. Availability varies significantly by region and waiting lists can be substantial. Through private prescription, you can access Mounjaro via a GPhC-registered online pharmacy following a clinical assessment with a UK-licensed prescriber. Private access does not require NHS referral. The KwikPen device contains 4 weekly doses, with costs varying by dose and provider, typically ranging from £150–£320 per month depending on your dose level. Starting doses are lower (2.5 mg) with weekly escalation, meaning a one-month supply may not achieve full therapeutic benefit before requiring continued treatment or discontinuation.
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 Routes and What One Month Really Means
If you're considering a single month of Mounjaro, it's important to understand that this timeframe is very short for weight management medication. The dose titration protocol means week 1–4 involves the lowest starting dose (2.5 mg), which is the adjustment phase. Meaningful weight loss typically emerges at higher maintenance doses (5 mg and above), which take weeks to reach. NHS access requires patience due to referral and waiting times. Private prescription offers faster access but involves an online clinical assessment to confirm eligibility and suitability. Either route, a one-month trial would only represent the early titration phase — most clinical guidance supports at least 12–16 weeks of treatment at therapeutic doses to assess effectiveness properly.
- 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.
Can you stop Mounjaro after just one month?
Technically yes — there's no requirement to continue beyond one month. However, one month covers only the initial dose titration phase (2.5 mg starting dose), not the therapeutic maintenance doses where weight loss typically occurs. Stopping early means you may not experience meaningful results. Your prescriber can discuss whether short-term use aligns with your health goals.
How much does one month of Mounjaro cost in the UK?
Private Mounjaro costs typically range from £150–£320 per month depending on your dose level. A 2.5 mg KwikPen costs around £150, while 15 mg pens cost approximately £320. NHS access is free but requires specialist referral and may involve waiting lists. Costs are per 4-week supply (one KwikPen).
What happens if you stop Mounjaro after one month?
Any weight lost during the first month may be regained after stopping, as the medication's appetite-suppressing effects stop immediately. Weight management typically requires ongoing treatment or sustained lifestyle changes. Discuss your goals with your prescriber — they can advise on realistic timescales for your situation.
Do you need a prescription for Mounjaro in the UK?
Yes, Mounjaro is prescription-only. You can access it through NHS specialist weight management services (referral required) or privately via an online clinical assessment with a UK-licensed prescriber. Both routes require a formal prescription issued by a qualified healthcare professional.
Is one month enough time to see results from Mounjaro?
One month is rarely enough to see substantial weight loss. The first 4 weeks involve the starting dose (2.5 mg) — the adjustment phase. Clinical trials showing meaningful weight loss (15–21% body weight) ran for 72 weeks at higher doses. Most prescribers recommend at least 12–16 weeks of treatment at therapeutic doses to fairly assess effectiveness.
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.