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 to Do If You Miss Your Mounjaro Injection for 2 Weeks
Missing a Mounjaro injection by 2 weeks falls outside the standard missed dose window and requires careful handling. Mounjaro (tirzepatide) is a once-weekly GLP-1 and GIP receptor agonist, and consistency matters for weight management results. If you've missed a dose by 2 weeks, you should contact your prescriber immediately rather than trying to catch up on your own. They'll assess your situation and advise whether to resume your regular schedule, skip that dose, or adjust your plan. This guidance applies whether you're accessing Mounjaro through the NHS or via private prescription in the UK.
10,000+ calculations today · NHS-aligned thresholds · 100% free
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.
Mounjaro Missed Dose Timing and Safe Guidance
Mounjaro's standard missed dose window is within 4 days of your scheduled injection. If you miss a dose by more than 4 days—such as 2 weeks—standard self-management guidance no longer applies, and you need prescriber input.
- Within 4 days of missed dose: Take your injection as soon as you remember, then continue your normal weekly schedule from that point.
- More than 4 days (including 2 weeks): Contact your GP or prescriber immediately. Do not attempt to "catch up" or double dose.
- Minimum interval: Always leave at least 72 hours (3 days) between injections.
A 2-week gap represents a significant break in your Mounjaro regime. Your prescriber may recommend you resume at your current dose on your next scheduled day, or they may suggest a different approach depending on how you're feeling and your overall progress. Consistency supports steady weight management results, so getting back on track promptly is important.
Clinically BackedWeight Loss
No appointments. No waiting rooms. Just care — from a UK-regulated online pharmacy.
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 Access and Next Steps
If you're receiving Mounjaro through NHS specialist weight management services, contact the clinic directly—do not wait for your next routine appointment. They'll provide specific guidance based on your clinical record. If you're accessing Mounjaro via private prescription, contact the prescriber or online clinic where you received your prescription; they can assess your situation via a brief follow-up consultation and confirm your next dose timing. In both routes, your prescriber may ask about your symptoms, appetite control, and any side effects before advising next steps. Use our free GLP-1 weight loss calculator to track your progress while you resolve the missed dose question—it can help you and your prescriber assess whether your current regime is working for your goals.
- 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.
Can I take two Mounjaro injections close together to make up for the 2-week gap?
No. Never take two doses within a short timeframe. The absolute minimum between injections is 72 hours (3 days). Taking doses too close together increases side effect risk. Always wait for prescriber guidance on when to resume your normal schedule.
Will missing Mounjaro for 2 weeks affect my weight loss results?
A single 2-week gap may slightly impact your progress, but it's not catastrophic. Consistency matters for sustained results. Once you resume, you can get back on track. Your prescriber will advise whether any adjustments are needed based on how you're responding overall.
Should I contact my GP or the clinic where I got my Mounjaro prescription?
Contact whoever prescribed your Mounjaro. If through NHS tier 3 services, contact that clinic directly. If through private online prescription, contact that provider. They have your medical history and can give personalised guidance quickly.
What if I don't remember exactly when I was supposed to inject?
If you're unsure of your scheduled day, check your Mounjaro KwikPen box, prescription records, or contact your prescriber with the date of your last injection. They can recalculate your schedule from that point and confirm when to resume.
Does missing one dose mean I need to restart the dose titration from the beginning?
Unlikely. Most prescribers will simply resume your current maintenance dose on the next scheduled day. Restarting titration (beginning at 2.5 mg again) is only done in specific situations—your prescriber will decide based on your clinical response and timeframe.
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.