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 Dose for 2 Weeks
If you've missed your Mounjaro injection for 2 weeks, it's important to act quickly but don't panic. Mounjaro is a prescription-only, once-weekly tirzepatide injection, and missing a dose by this length of time means you're outside the standard missed dose window. Your next step is to contact your prescriber or GP as soon as possible for guidance on whether to take a dose now or wait until your next scheduled injection day. This guide explains what you need to know and how to get back on track safely.
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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.
When a Mounjaro Dose Is Considered Truly Missed
The standard guidance for a missed Mounjaro dose is:
- If fewer than 4 days have passed since your injection day, take your dose as soon as you remember and continue your normal weekly schedule
- If more than 4 days have passed, skip that dose and resume your regular weekly schedule on your next planned injection day
At 2 weeks (14 days) past your scheduled injection, you are significantly beyond the 4-day window. This means you should not take a double dose to "catch up". Instead, contact your GP or prescriber immediately to clarify the best approach for your individual situation. They may advise you to skip to your next regularly scheduled injection day, depending on your dose level, how long you've been on Mounjaro, and your response so far. Your prescriber can also check whether any side effects or weight changes occurred during the missed period.
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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.
Why You Shouldn't Skip Multiple Weeks Going Forward
Missing a single dose by 2 weeks is manageable with prescriber guidance, but consistency matters for weight management results. Mounjaro works best as a regular weekly injection—skipping doses or inconsistent timing can affect appetite suppression, blood sugar control (if relevant), and overall effectiveness. If you're struggling to remember your weekly injection, set a phone reminder for the same day each week, use a medication app, or ask your prescriber about strategies to help. You can also use our free progress tracker to log your injections and track your weight loss journey alongside your Mounjaro schedule, making it easier to spot missed doses before they become a bigger gap.
- 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 at once to make up for a 2-week gap?
No. Never take a double dose. Taking two doses together could increase side effects like nausea, vomiting, and stomach pain. Instead, contact your prescriber. They will advise whether to skip that week's dose and resume on your next scheduled day, or adjust your timeline based on your individual situation.
Will missing one dose set back my weight loss progress?
One missed dose is unlikely to cause significant weight loss reversal, especially if you're only 2 weeks off schedule. However, Mounjaro works best with consistent weekly dosing. Your appetite and satiety signals may return slightly during the missed period, but restarting on schedule should restore the effect. Your prescriber can advise further.
What if I missed my dose because I couldn't access my Mounjaro prescription?
Contact your GP or prescriber immediately. If you're getting Mounjaro through the NHS, they can check your prescription status or arrange an urgent appointment. If through private prescribing, contact your provider. Don't try to resume without guidance—your prescriber needs to know the reason for the gap and confirm it's safe to continue.
How is missing Mounjaro different from missing Wegovy?
Both are once-weekly injections with similar missed-dose guidance: within 4 days, take it; after 4 days, skip and resume next week. The main difference is mechanism: Mounjaro is a dual GIP/GLP-1 agonist, while Wegovy (semaglutide) is GLP-1 only. For a 2-week gap, the action is the same—contact your prescriber before restarting.
Should I be concerned about side effects when I restart after 2 weeks?
Side effects like nausea are often worse when restarting after a break. Your prescriber may advise starting cautiously or adjusting your next dose timing. Most side effects settle within a few days. Stay hydrated, eat small frequent meals, and contact your GP if symptoms are severe.
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.