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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Does Mounjaro Cause Insomnia — And What Does It Cost in the UK?
Sleep disturbances, including insomnia, are not listed as a common side effect of Mounjaro (tirzepatide) in UK clinical data or the product information, though some people report sleep changes when starting this prescription weight management injection. Understanding potential side effects, costs, and how to access Mounjaro in the UK can help you make an informed decision about whether this GLP-1 dual agonist medication is right for you. This guide covers everything from eligibility and NHS access to private prescription costs and what to expect during your first weeks of treatment.
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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.
Sleep Issues with Mounjaro: What the Evidence Shows
Sleep disturbances are not listed as a very common or common side effect in UK Mounjaro prescribing information. However, sleep changes can occur indirectly through several mechanisms. Nausea, one of the most frequent side effects reported in clinical trials, may make sleeping difficult for some people. Additionally, when your body adjusts to changes in appetite regulation and food intake, circadian rhythm adjustments can occasionally affect sleep patterns. Some people report fatigue (listed as a common side effect), which may indicate sleep quality changes rather than insomnia itself.
If you experience sleep problems after starting Mounjaro, it's important to report this to your prescriber. Sleep issues may also relate to underlying conditions, other medications, or lifestyle factors rather than Mounjaro itself. Your GP or prescriber can assess whether your specific symptoms warrant dose adjustment or further investigation.
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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.
Mounjaro Cost and Access in the UK: NHS vs Private
NHS Access: Mounjaro is available through NHS tier 3 specialist weight management services. You'll need a GP referral and meet eligibility criteria (BMI 30+, or BMI 27+ with weight-related health conditions). Waiting times vary significantly by region, often months to over a year.
Private Route: Via GPhC-registered online prescription services. Costs typically range from £129–£320 per month depending on your dose. You'll complete an online consultation with a UK-licensed prescriber, who assesses suitability before issuing a prescription. The Mounjaro KwikPen (a pre-filled injection device) is then dispensed by a registered pharmacy. Private access avoids NHS waiting lists but requires personal payment.
- 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.
Is insomnia a common side effect of Mounjaro in the UK?
No. Insomnia is not listed as a common or very common side effect in UK product information. However, nausea and fatigue (both common side effects) may indirectly affect sleep quality. Always report persistent sleep problems to your prescriber to rule out other causes.
How much does Mounjaro cost privately in the UK?
Private Mounjaro costs typically range from £129–£320 per month, depending on your dose (2.5 mg to 15 mg weekly). Costs vary between online prescription providers. Some services offer dose-based pricing or subscription models. Always check the full cost breakdown before committing.
Can I get Mounjaro on the NHS in the UK?
Yes, through NHS tier 3 specialist weight management services. You need a GP referral and must meet eligibility criteria (BMI 30+, or 27+ with weight-related health conditions). Regional availability and waiting times vary greatly — some areas have waiting lists exceeding 12 months.
What's the difference between Mounjaro and Wegovy for sleep?
Both are GLP-1-type weight management injections. Mounjaro is a dual GIP/GLP-1 agonist; Wegovy is a GLP-1 agonist only. Neither lists insomnia as a common side effect. Nausea, the main sleep-disrupting side effect, is similar between both medications. Individual responses vary, and your prescriber can discuss which suits you better.
How long does it take to access Mounjaro privately in the UK?
Online consultation services typically provide prescriptions within 24–48 hours if approved. Your pharmacy dispenses the Mounjaro KwikPen within 2–5 working days. Total time from initial consultation to first injection: often under one week. NHS access is significantly slower due to referral and waiting list processes.
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.