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 Happens When Mounjaro Wears Off?
If you've been taking Mounjaro and notice your appetite returning or weight plateauing, you may be experiencing the medication wearing off between doses or over time. This is common and usually means a dose adjustment or medication review is needed. In the UK, managing this involves speaking with your prescriber about your options—whether that's increasing your tirzepatide dose, continuing at your current level, or exploring alternatives like Wegovy. Understanding your access route and costs can help you plan next steps effectively.
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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.
UK Private Costs and Access Routes for Mounjaro
In the UK, Mounjaro is available through both NHS specialist weight management services and private online prescribing routes. NHS access is through tier 3/4 specialist services, typically following GP referral, though waiting times and availability vary significantly by region. Private access is available through GPhC-registered online pharmacies following a digital consultation with a UK-licensed prescriber—no NHS referral needed.
Private Mounjaro costs in the UK typically range from £150–£280 per month depending on your dose. The KwikPen (containing 4 weekly injections) costs vary by dose:
- 2.5 mg–5 mg: approximately £150–£180
- 7.5 mg–10 mg: approximately £200–£240
- 12.5 mg–15 mg: approximately £250–£280
When your prescriber reviews your response to Mounjaro and suggests a dose increase, costs will rise accordingly. Some people also switch to Wegovy (semaglutide) if Mounjaro effects diminish, though this requires a new prescription and clinical assessment.
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: Your Options When Effects Wear Off
If you're on NHS Mounjaro through a specialist service and effects are wearing off, contact your clinic directly—they will review your response and adjust your dose or suggest next steps. Private route: Schedule a follow-up consultation with your prescriber (usually available within days). They'll assess whether a dose increase is appropriate based on your KwikPen usage, side effects, and weight loss goals. Many private providers offer flexible consultation options to address concerns quickly. Use our GLP-1 weight loss calculator to explore projected outcomes at different tirzepatide doses, helping you understand what to expect before discussing adjustments with your prescriber. Whichever route you use, dose adjustments should be made gradually—minimum 4 weeks between each increase.
- 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.
Why does Mounjaro seem to wear off over time?
Mounjaro may feel less effective due to several reasons: your body may have partially adapted to the medication, you may need a dose increase as part of normal titration, side effects (nausea/vomiting) may ease so appetite sensations return, or you may have reached a weight plateau where further loss is slower. Your prescriber can assess which applies to you.
Can I increase my Mounjaro dose if it's wearing off?
Yes—dose increases are a normal part of Mounjaro treatment. The standard protocol involves staying on each dose for at least 4 weeks before escalating. Doses range from 2.5 mg up to 15 mg weekly. Your prescriber will decide if increasing is appropriate based on your response, weight loss, and side effects.
What's the difference between Mounjaro and Wegovy when effects wear off?
Mounjaro (tirzepatide) is a dual GIP and GLP-1 agonist; Wegovy (semaglutide) is a GLP-1 agonist only. Mounjaro may provide stronger appetite suppression initially, but some people switch to Wegovy if they adapt to tirzepatide. Clinical trial data showed Mounjaro achieved ~15–21% average weight loss, Wegovy ~15%. Switching requires a new prescription and clinical assessment.
How quickly can I get a dose adjustment through private prescribing?
Most private online prescribers can arrange a follow-up consultation within 2–5 working days. After assessment, a new prescription for a higher dose can be issued and dispensed by a GPhC-registered pharmacy within 1–2 days. NHS routes depend on your specialist clinic's appointment availability, which varies by region.
Will my costs change if I increase my Mounjaro dose?
Yes—higher doses cost more. Moving from 5 mg to 10 mg, for example, typically increases monthly costs by £40–£60. Your prescriber will discuss dose options with you; our BMI calculator and weight converter can help you track progress and understand whether further increases are worth exploring.
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.