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 Every 6 Days — What You Need to Know
Mounjaro is a prescription-only injection designed to be taken once weekly (every 7 days), but some people ask about spacing doses every 6 days instead. This guide explains the approved dosing schedule, why the standard once-weekly timing matters, and what NHS guidance says about deviating from the standard protocol. Always consult your GP or prescriber before changing any injection schedule.
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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.
Mounjaro Standard Dosing Schedule in the UK
Mounjaro (tirzepatide) is approved in the UK as a once-weekly injection, meaning one dose every 7 days. The standard dosing protocol follows this timeline:
- Weeks 1–4: 2.5 mg once weekly (starting dose)
- Weeks 5–8: 5 mg once weekly
- Weeks 9–12: 7.5 mg once weekly
- Weeks 13–16: 10 mg once weekly
- Weeks 17–20: 12.5 mg once weekly
- Week 21+: 15 mg once weekly (maximum)
Each Mounjaro KwikPen contains 4 doses (4 weeks' supply). Injecting every 6 days shortens this interval and means you would use more doses in less time, requiring more pens per month and potentially higher costs. This schedule is not part of the approved prescribing guidance in the UK.
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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.
Can You Inject Mounjaro Every 6 Days Instead of Weekly?
Shortening the interval to every 6 days is not recommended and not part of the approved UK dosing schedule. The once-weekly dosing was established in clinical trials (SURMOUNT-1) and is the basis for all UK licensing and NHS guidance. Injecting more frequently could alter how the medication works in your body and may increase the risk of side effects without additional benefit.
If you're considering changing your injection schedule: speak to your GP or prescriber immediately. They can assess why you're thinking about this change (side effects? cost concerns? effectiveness questions?) and work with you on a safe solution. This might include dose adjustments, timing strategies, or discussing whether Mounjaro is still the right medication for you.
- 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.
Why is Mounjaro once weekly and not every 6 days?
Mounjaro was designed and clinically tested as a once-weekly injection. This 7-day interval allows the medication to build up safely in your system and maintain steady levels between doses. The SURMOUNT trials established this as the safe and effective schedule. Shortening it could alter how it works.
Would injecting every 6 days make you lose weight faster?
There's no evidence that injecting more frequently would increase weight loss. In fact, more frequent dosing could destabilise the medication's effect and increase side effects. Clinical trials showed effectiveness at once-weekly dosing — deviating from this may not help and could cause problems.
Is injecting Mounjaro every 6 days medically safe?
There is no safety data for every 6 days dosing because it's not part of the approved UK protocol. Only the once-weekly schedule has been tested and approved by the MHRA. Always follow your prescriber's instructions or discuss changes with your GP before adjusting any dosing schedule.
What if I keep missing my weekly injection by a day or two?
If you're consistently late by a day or two, that's different from intentionally shortening the interval. Missing doses within 4 days is manageable — just take it as soon as you remember and continue your normal weekly schedule. If timing is difficult, discuss this with your prescriber for practical solutions.
Can my GP change my Mounjaro schedule to every 6 days?
Your GP would need very strong clinical reasons to deviate from the approved once-weekly schedule, and this would be unusual. If you have concerns about your current schedule (side effects, access, cost, or efficacy), your prescriber can discuss alternative approaches — like adjusting the dose, trying a different medication, or modifying your lifestyle alongside treatment.
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.