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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How to Restart Mounjaro After 3 Weeks in the UK
If you've paused your Mounjaro treatment after 3 weeks, you may be wondering how to safely restart and what options are available to you in the UK. Restarting depends on why you stopped, whether you're accessing treatment through the NHS or privately, and your individual health circumstances. This guide covers the practical steps, costs, and eligibility criteria for restarting this prescription-only tirzepatide injection 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.
Private Prescription Costs and Restart Options
If you were accessing Mounjaro privately through an online prescription service, restarting typically involves a follow-up consultation with a UK-licensed prescriber. The cost to restart depends on your current dose: each Mounjaro KwikPen contains 4 weekly doses, and prices range from approximately £129–£320 per pen depending on whether you're restarting at your original dose (e.g., 5 mg) or resuming a higher maintenance dose (e.g., 10 mg or 15 mg).
Before restarting, expect a brief online clinical assessment to confirm it's safe to resume — especially important if you stopped due to side effects or health changes. Your prescriber will review why you paused and may recommend restarting at your previous dose or stepping down to a lower starting dose (e.g., 2.5 mg) if you've been off the injection for more than a few weeks. Individual results vary, and the cost of restarting reflects the dose strength, not assured outcomes.
- Standard restarting consultation: typically included or a small fee (£15–£30)
- Mounjaro KwikPen cost: £129–£320 per pen (4 doses)
- Most providers offer repeat prescription discounts for returning users
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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 Restart: Which Route Is Right for You?
NHS restart: If you were prescribed Mounjaro through an NHS specialist weight management service (tier 3), restarting requires contact with your service. Waiting times for assessment and resumption vary significantly by region and current service capacity. Some NHS services may require a new referral if your initial course was discontinued, while others will fast-track existing patients. There is no cost on the NHS, but availability and timescales differ across UK regions.
Private restart: Much faster — typically within 24–48 hours of completing an online consultation. You'll have a conversation with a prescriber, answer health questions, and receive a prescription if appropriate. Dispensed by a GPhC-registered pharmacy, usually delivered within 3–5 working days. Better for those who want quick resumption without NHS waiting lists, though at a cost. Use our free GLP-1 weight loss calculator to help inform your discussion with your prescriber about dose and projected outcomes.
NHS restart: If you were prescribed Mounjaro through an NHS specialist weight management service (tier 3), restarting requires contact with your service. Waiting times for assessment and resumption vary significantly by region and current service capacity. Some NHS services may require a new referral if your initial course was discontinued, while others will fast-track existing patients. There is no cost on the NHS, but availability and timescales differ across UK regions.
Private restart: Much faster — typically within 24–48 hours of completing an online consultation. You'll have a conversation with a prescriber, answer health questions, and receive a prescription if appropriate. Dispensed by a GPhC-registered pharmacy, usually delivered within 3–5 working days. Better for those who want quick resumption without NHS waiting lists, though at a cost. Try our free GLP-1 weight loss calculator to help inform your discussion with your prescriber about dose and projected outcomes when you restart 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 there a gap penalty if I restart Mounjaro after 3 weeks?
No clinical "penalty" — restarting after 3 weeks is medically safe. Your prescriber may recommend starting at your previous dose or stepping back to a lower dose depending on why you stopped and how you felt. Individual results vary, and any restart should follow a clinical assessment with your prescriber.
How much does it cost to restart Mounjaro privately in the UK?
A private Mounjaro KwikPen (4 doses) costs approximately £129–£320 depending on dose strength (5 mg, 10 mg, 15 mg). Consultation fees range from £15–£30. Total first restart typically costs £150–£350. Repeat prescriptions from the same provider often have discount options.
Can I restart Mounjaro on the NHS after stopping privately?
Potentially yes, but it requires a new referral to your NHS tier 3 weight management service or your GP. You cannot switch directly from private to NHS mid-treatment. NHS assessment and approval may take weeks or months depending on your region and service availability.
What happens if I restart Mounjaro at the same dose I stopped at?
Restarting at the same dose is often safe if you've been off for only 3 weeks. Your prescriber will assess your health and reason for stopping. If you had side effects, they may recommend a lower starting dose. If you tolerated it well, restarting at the same dose may allow faster progress toward your previous maintenance dose.
Do I need another clinical assessment to restart, or can I just order more?
You must have a clinical assessment before restarting — whether NHS or private. This is a prescription-only medicine, and a UK-licensed prescriber must confirm it's safe for you to resume based on your current health. Online private assessments usually take 15–30 minutes and can be completed same-day.
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.