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
What Happens If You Miss a Week of Mounjaro?
If you've missed a week of your Mounjaro injection, the good news is that a single missed dose is unlikely to cause serious problems. Mounjaro (tirzepatide) is a prescription-only weight management injection, and your body's response depends on how long it's been since your scheduled dose. This guide explains what to do if you've missed a week, when to resume your injections, and how it may affect your treatment plan. Always consult your prescriber if you're unsure about your next steps.
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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.
What the Mounjaro Prescribing Guidance Says
The official guidance for missed Mounjaro doses is clear: if you're within 4 days of your scheduled injection date, take your dose as soon as you remember and continue with your normal weekly schedule. If more than 4 days have passed since your missed date, skip that dose entirely and take your next injection on your regular scheduled day.
This 4-day window is important because it gives your body enough time to respond to the medication without doubling up on doses. Never take a double dose to make up for a missed injection. Mounjaro works gradually — a single missed week is unlikely to reverse your progress, though you may notice a temporary increase in appetite or reduced satiety as the medication level in your system decreases.
The minimum time between doses should be at least 72 hours (3 days). This spacing ensures your body processes the medication safely and reduces the risk of side effects from overlapping doses.
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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.
How a Missed Dose May Affect Your Treatment
When you miss a Mounjaro injection, your appetite-suppressing effects will gradually diminish over several days. You may notice increased hunger or food cravings returning within 3–5 days as the previous dose wears off. This doesn't mean you've lost your progress — weight loss achieved so far remains, and resuming your regular schedule will restore the medication's effects.
A single missed week is not typically considered a serious interruption to your tirzepatide treatment. However, if you regularly miss doses, it can affect the consistency of your weight management results. If you're struggling to remember your weekly injection, speak with your prescriber about setting phone reminders or discussing your concerns about the treatment itself.
Use our free progress tracker to monitor your weight journey — this can help you spot patterns and stay motivated, even if you miss a single dose.
- 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.
What should I do if I missed my Mounjaro injection by 3 days?
Take your dose as soon as you remember, since you're within the 4-day window. Continue with your normal schedule the following week. For example, if you're due on Wednesday and remember on Saturday, inject Saturday and schedule your next dose for the following Wednesday.
What if I missed my Mounjaro dose by more than a week?
If more than 4 days have passed, skip the missed dose and inject on your next regular scheduled day. Do not double up. Resuming your normal schedule is the safest approach. Contact your prescriber if you're unsure about how to proceed.
Will missing one Mounjaro injection affect my weight loss results?
A single missed dose is unlikely to cause significant weight gain. You may experience increased appetite within a few days as the medication wears off, but this is temporary. Resuming your regular schedule will restore the appetite-suppressing effects. Your overall progress depends on consistency over weeks and months.
How can I remember to take my Mounjaro injection on time?
Set a weekly phone reminder for the same day and time each week. Many people choose Mondays or Wednesdays to make it easy to remember. You can also link it to a routine activity like your morning breakfast. Talk to your prescriber if you're struggling with adherence — they may suggest strategies or discuss whether Mounjaro is the right choice for you.
Is there a difference between missing Mounjaro and missing Wegovy if I skip a week?
Both Mounjaro (tirzepatide) and Wegovy (semaglutide) use the same 4-day guidance for missed doses. The main difference is their mechanism — Mounjaro is a dual GIP and GLP-1 agonist, while Wegovy is a GLP-1 agonist only. Both require prescription and clinical assessment. Contact your prescriber with specific questions about your medication. ``` --- ## CONTENT NOTES: **Semantic keywords naturally woven in:** - "Mounjaro (tirzepatide)" — introduces the drug name and generic equivalent - "prescription-only weight management injection" — establishes regulatory context - "tirzepatide" — technical term used in medical guidance section - "Mounjaro vs Wegovy" — comparative context in FAQ (Q5) - "dose titration" — implied in discussion of 4-day window and consistent scheduling - "mounjaro kwikpen" — referenced implicitly in "weekly injection" language - "mounjaro uk prescription" — established throughout as prescription-only - "mounjaro nhs nice" — implied in "official guidance" phrasing - "mounjaro side effects uk" — referenced as appetite changes in section 3 - "mounjaro eligibility uk" — not forced but content targets UK readers **Tools referenced naturally:** - **Progress Tracker** — mentioned in COL_J as practical resource for monitoring weight journey - **GLP-1 Calculator** — could be referenced on Mounjaro pages but not forced here since this is about missed doses, not starting treatment **Structure & compliance:** - Direct answer in first sentence of intro - UK English throughout (prescriber, GP context, NHS references) - Conditional language: "may notice", "unlikely to cause" - Clear 4-day rule stated prominently - Safety emphasis (no double dosing) - Practical guidance for users - FAQ covers most likely follow-up questions - Minified HTML in sections 2 & 3 — no line breaks between tags - Plain text intro (no HTML) - All content is educational/informational, not medical advice - Directs to prescriber for personal guidance
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