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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Can Mounjaro Affect Mood and Mental Health?
Mounjaro (tirzepatide) is a prescription-only GLP-1 and GIP receptor agonist used for weight management in the UK. While mood changes are not listed as a common side effect in clinical trials, some people report feeling emotionally different during treatment. This guide explains what we know about Mounjaro and mood, how it compares to Wegovy, and what to do if you experience changes to your mental health. Always speak to your GP if you have concerns.
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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.
What the Clinical Evidence Shows About Mounjaro and Mood
In the SURMOUNT clinical trials, mood changes were not recorded as a frequent side effect of tirzepatide. The most commonly reported side effects were gastrointestinal — nausea, vomiting, diarrhoea, and constipation. However, some users report feeling emotionally flat, anxious, or experiencing mood swings during treatment. These experiences are anecdotal rather than formally documented in UK clinical data.
Mood can be affected indirectly by weight loss medications in several ways: gradual weight management itself can influence hormone levels and mental wellbeing; gastrointestinal discomfort may affect mood and energy; and the psychological impact of significant weight loss can be complex. The relationship between GLP-1 medications and mood is still being studied. If you experience persistent mood changes after starting Mounjaro, always report this to your GP or the prescriber — they can assess whether the medication is suitable for you or whether adjustments are needed.
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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.
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Mounjaro Access in the UK: NHS vs Private Cost Options
In the UK, Mounjaro access differs significantly between NHS and private routes. NHS access is through tier 3 specialist weight management services — you'll need a GP referral and an assessment, though availability and waiting times vary greatly by region. Private access involves an online consultation with a UK-licensed prescriber; if approved, your prescription is dispensed by a GPhC-registered pharmacy. Private Mounjaro typically costs £160–£320 per month depending on dose, with the 2.5 mg starting dose at the lower end. Both routes require a clinical assessment to confirm you're eligible — your prescriber will review your BMI, weight-related health conditions, medications, and medical history before treatment begins.
- 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.
Does Mounjaro directly cause depression or anxiety?
Clinical trials do not list mood disorders as common side effects of tirzepatide. However, some users report mood changes anecdotally. Mood can be indirectly affected by gradual weight management, gastrointestinal symptoms, or hormonal shifts. If you experience mood changes, report them to your GP immediately — they can assess whether Mounjaro is appropriate for you.
How much does Mounjaro cost privately in the UK?
Private Mounjaro costs approximately £160–£320 per month in the UK, depending on your dose. The starting dose (2.5 mg) is cheaper than higher maintenance doses (15 mg). Prices vary between different GPhC-registered pharmacies. Always check current pricing with your prescriber before starting treatment.
Can I get Mounjaro on the NHS?
Yes, Mounjaro is available through NHS tier 3 specialist weight management services if you meet eligibility criteria (BMI ≥30, or ≥27 with weight-related health conditions). However, availability varies by region, and waiting lists can be lengthy. Your GP can refer you to your local specialist service.
What's the difference between Mounjaro and Wegovy for mood?
Both are prescription weight loss injections, but Mounjaro is a dual GIP and GLP-1 agonist, while Wegovy (semaglutide) is a GLP-1 agonist only. Neither lists mood changes as a common side effect. Individual responses vary. Your prescriber can help you decide which is most appropriate based on your health history.
What should I do if Mounjaro makes my mood worse?
Contact your GP or prescriber immediately. Do not stop taking Mounjaro without medical guidance. Your prescriber will assess whether the symptoms are related to the medication, adjust your dose, or switch you to an alternative treatment. Mental health concerns should always be taken seriously.
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