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
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What Happens to Side Effects After Stopping Mounjaro?
When you stop taking Mounjaro (tirzepatide), the injection-related side effects typically resolve within days to weeks as the medication leaves your system. However, some people experience rebound effects, including return of appetite, nausea or digestive changes, and potential weight regain. Understanding what to expect after stopping — and how to manage the transition — helps you plan your next steps. This guide covers the timeline, common experiences, and UK access options if you need support during the stopping process.
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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.
Timeline of Side Effects After Stopping Mounjaro
Most injection site reactions and common side effects resolve quickly:
- Within 2–7 days: Nausea, diarrhoea, and stomach discomfort typically improve as the active drug clears
- Within 1–2 weeks: Constipation, indigestion, and appetite suppression usually fade
- Within 2–4 weeks: Hair loss (alopecia) may continue briefly as it reflects earlier physiological stress, but typically stabilises
However, the timing varies. Your body's response depends on your dose, how long you took Mounjaro, your metabolism, and individual factors. Rebound appetite — where hunger returns to pre-treatment levels — is one of the most commonly reported experiences. This is not a side effect of stopping, but rather your appetite hormones (GIP and GLP-1 signalling) normalising. Weight regain can also occur, especially without ongoing dietary and lifestyle support.
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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.
Managing the Transition and Access to Ongoing Support
If you're stopping Mounjaro through the NHS, your specialist team should provide guidance on managing the transition and maintaining any weight loss achieved. If you're accessing Mounjaro through private prescription via an online consultation, contact your prescriber before stopping to discuss next steps.
Practical strategies during the transition:
- Maintain structured meal patterns and balanced nutrition to manage rebound appetite
- Continue physical activity — exercise supports both mental health and weight stability
- Track your progress with a free tool to monitor any changes and stay motivated
- Consider whether further weight management support (such as dietary advice or alternative GLP-1 medication like Wegovy) might help
- Speak to your GP if you experience persistent or concerning symptoms
- 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.
How long does it take for Mounjaro side effects to stop after stopping the injection?
Most side effects resolve within 1–4 weeks as the medication clears your body. Nausea and stomach upset typically improve within 2–7 days. Appetite suppression fades within 1–2 weeks. Hair loss may continue briefly but usually stabilises within a few weeks. Individual timelines vary based on dose, duration of treatment, and personal metabolism.
Will my appetite come back after I stop Mounjaro?
Yes, appetite typically returns as your body's natural GLP-1 and GIP signalling normalises. This is called rebound appetite. For many people, hunger returns to pre-treatment levels. This is normal and not a side effect — it's your body's natural response. Maintaining structured eating patterns and staying active can help manage this transition.
Will I regain weight after stopping Mounjaro?
Weight regain is possible after stopping, especially without ongoing dietary and lifestyle support. How much you regain depends on whether you maintain the eating and activity habits you developed during treatment. Some people maintain their weight loss long-term, while others experience partial or full regain. Your GP or a weight management specialist can help you plan a sustainable strategy.
What's the difference between stopping Mounjaro and stopping Wegovy?
Both are GLP-1-based weight loss injections, but Mounjaro is a dual GIP/GLP-1 agonist while Wegovy is a GLP-1 agonist only. The side effect timeline after stopping is similar — typically 1–4 weeks — though individual responses vary. Your prescriber can advise which medication might suit you better if you're considering alternatives.
Can I switch to another weight loss medication instead of stopping completely?
Yes. If you're stopping Mounjaro due to side effects or other reasons, your prescriber may recommend switching to an alternative such as Wegovy (semaglutide) or continuing with lifestyle support alone. A UK-licensed prescriber can assess whether another GLP-1 medication, a different dose, or a different approach might work better for you. Always discuss options with your prescriber before changing treatment.
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.