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 Miss a Dose of Mounjaro?
Yes, you can miss a dose of Mounjaro (tirzepatide), and there are clear guidelines for what to do if this happens. Missing an occasional injection is not dangerous, but it's important to understand the correct steps to take and when to resume your normal schedule. This guide explains the NHS-aligned approach to missed doses and answers common questions about Mounjaro dosing in the UK.
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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.
What to Do If You Miss a Mounjaro Dose
If you miss your Mounjaro injection, the action you take depends on how long it has been since your scheduled dose. Mounjaro is a once-weekly injection — each KwikPen contains four doses (one month's supply). The timing of a missed dose affects whether you should take it immediately or skip to your next scheduled injection.
- Within 4 days: Take your missed dose as soon as you remember, then continue your normal weekly schedule from that point
- More than 4 days since your scheduled dose: Skip the missed dose entirely and take your next injection on your normally scheduled day
- Never take a double dose to make up for a missed injection — this increases the risk of side effects
- Minimum time between doses: Always leave at least 72 hours (3 days) between injections
If you are unsure about timing, contact your prescriber or GP for guidance. Missing one dose will not affect your overall treatment plan, though consistent adherence produces the best results.
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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.
Storage and Preventing Missed Doses
Many missed doses happen due to storage or reminder issues. Unopened Mounjaro pens must be stored in a refrigerator at 2–8°C and must not be frozen. After first use, a pen can be kept at room temperature (below 30°C) for up to 30 days. Set a weekly reminder on your phone or calendar for your injection day — most people inject on the same day each week, making it easier to remember. If you struggle with adherence, discuss this with your GP or prescriber; they may suggest strategies or tools to help you maintain consistency with your tirzepatide 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.
What happens to my weight loss if I miss a Mounjaro dose?
Missing a single dose will not significantly impact your overall weight loss journey, as long as you resume your injections on schedule. Consistent use over weeks and months produces the best results, so occasional missed doses are unlikely to derail progress. However, regular missed doses may affect your outcomes — aim for adherence each week.
Can I take two Mounjaro injections close together if I miss one?
No. Never take two doses close together, and always leave at least 72 hours (3 days) between injections. Taking double doses or injecting too soon increases the risk of side effects without additional benefit. Follow the 4-day window guidance above.
Should I tell my GP if I miss a Mounjaro dose?
An occasional missed dose does not require a GP report. However, if you find you are regularly missing doses, discuss this with your prescriber or GP. They can help identify barriers to adherence and may offer support or alternative strategies to help you stay on track.
Does missing a Mounjaro dose affect the dose titration schedule?
If you miss a dose within the 4-day window, take it and continue your normal weekly schedule. Your titration plan (the gradual increase from 2.5mg to higher doses) remains on track. If you miss by more than 4 days, skip that dose and continue as normal — your titration timing does not change.
What if I miss multiple doses of Mounjaro?
Missing multiple doses may affect your weight loss progress and could disrupt your dose titration schedule. If you experience ongoing difficulties remembering injections, speak to your prescriber about solutions. They may also review whether Mounjaro remains the right choice for your circumstances, or discuss barriers to adherence you may be facing.
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.