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 Skip a Week on Mounjaro?
If you're taking Mounjaro (tirzepatide), you may wonder what happens if you skip a dose or miss your weekly injection. The answer depends on how long you've missed it. In most cases, you can catch up if you're within 4 days of your scheduled injection date. However, understanding the guidance for missed doses is important to keep your treatment on track and avoid side effects or reduced effectiveness. This guide explains what to do if you skip a week on Mounjaro 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.
Mounjaro Missed Dose Guidance
Mounjaro is a once-weekly injection containing tirzepatide, prescribed for eligible UK adults with excess weight. Missing or delaying your injection can affect how well the medication works and your appetite regulation.
If you miss your Mounjaro dose:
- Within 4 days: Inject as soon as you remember, then continue your normal weekly schedule from that day
- More than 4 days late: Skip that dose and inject your next dose on your normal scheduled day — do not double up
- Less than 3 days (72 hours) since your last injection: Wait until your next scheduled day — do not inject early
The key principle is maintaining at least 72 hours (3 days) between doses. Skipping doses occasionally is unlikely to cause serious harm, but consistent missed injections may reduce the medication's effectiveness. If you're struggling to remember your weekly injections, setting a phone reminder or marking your calendar can help you stay on schedule.
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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 and Private Mounjaro Access in the UK
NHS access to Mounjaro is through specialist tier 3 weight management services, typically requiring a GP referral. Availability varies significantly by region, and waiting lists can be lengthy. Once prescribed through the NHS, your GP surgery will manage your injections and monitor your progress.
Private access is available through UK-licensed online prescribers following a clinical assessment. Private prescriptions are then dispensed by GPhC-registered pharmacies. Whether you're accessing Mounjaro on the NHS or privately, your prescriber will provide clear guidance on injection timing and what to do if you miss a dose. Track your weight loss progress using our free weight loss calculator to monitor how consistently taking your injections affects your results over time.
- 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 if I skip a Mounjaro injection completely?
If you skip one injection entirely, you may notice increased appetite the following week as the medication's effects wear off. Your prescriber can advise whether to continue your normal schedule or adjust your dose plan. Consistently missing doses reduces treatment effectiveness, so it's best to stay on schedule.
Can I delay my Mounjaro injection by a few days?
Yes, you can delay by up to 4 days without needing to skip the dose. Simply inject when you remember, then resume your normal weekly schedule. However, maintain at least 72 hours between any two injections — never inject early to "catch up".
Should I contact my GP if I miss a Mounjaro dose?
If you miss one dose within the 4-day window, you don't need to contact your GP — just inject when you remember. However, if you regularly miss doses or have questions about your injection schedule, contact your prescriber or GP for guidance.
Does missing a Mounjaro dose cause serious side effects?
Missing a single dose is unlikely to cause serious harm. However, you may experience increased appetite and food cravings as the medication's effects diminish. Staying consistent with your weekly injections helps maintain stable appetite suppression.
What's the best way to remember my weekly Mounjaro injection?
Set a recurring phone reminder for the same day and time each week (e.g. every Wednesday at 10 am). Many people also keep their Mounjaro KwikPen in a visible place, like next to their toothbrush or on the kitchen counter, as a visual reminder to inject on schedule.
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.