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
Does Mounjaro Cause Depression?
Depression and mood changes are not listed as common side effects of Mounjaro in clinical trials, though some people report emotional changes when using GLP-1 or dual GIP/GLP-1 medications like tirzepatide. Any significant mood changes should be reported to your GP or prescriber immediately. Mounjaro is a prescription-only weight management injection licensed in the UK, and mental health screening is part of the clinical assessment before you're prescribed it. This guide covers what the evidence shows, how to access Mounjaro safely, and what to do if you experience mood concerns while taking it.
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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.
What the Evidence Shows About Mounjaro and Mood
In the SURMOUNT clinical trials, depression was not reported as a common side effect of Mounjaro (tirzepatide). However, some patients taking GLP-1 medications have reported mood-related experiences, which may reflect either the medication itself or changes associated with significant weight loss.
Key points:
- Depression is not listed in the "very common" or "common" side effects sections of the Mounjaro patient information
- Mood changes can occur with any medication — individual responses vary
- gradual weight management itself can affect mood, energy, and psychological wellbeing
- Pre-existing mental health conditions may be affected differently by weight loss and medication
- Nausea, fatigue, and appetite suppression may indirectly affect mood through general wellbeing
If you experience persistent sadness, hopelessness, or any concerning mood changes while taking Mounjaro, contact your GP or prescriber immediately.
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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.
Accessing Mounjaro in the UK — NHS vs Private Routes
You can access Mounjaro through two routes in the UK. NHS access requires referral to a specialist tier 3 weight management service through your GP — availability varies by region and waiting lists can be lengthy. Private access is faster: complete an online consultation with a UK-licensed prescriber, receive a prescription if clinically appropriate, and have Mounjaro dispensed by a GPhC-registered pharmacy.
Before any prescription, you'll be asked about mental health history, current medications, and any existing conditions. This screening helps ensure Mounjaro is safe for you. Private prescriptions typically cost £130–£300 per month depending on your dose (2.5 mg starting dose through to 15 mg maximum). Both routes require an ongoing relationship with a prescriber who monitors your progress and adjusts your dose gradually.
- 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 Mounjaro cause depression if I've never had mental health issues?
Depression is not a common side effect of Mounjaro in clinical trials. However, any medication can affect individuals differently. If you experience mood changes while taking Mounjaro, report them to your GP or prescriber. They may adjust your dose or consider an alternative treatment.
What should I do if I feel depressed while taking Mounjaro?
Contact your GP or prescriber immediately. Do not stop taking Mounjaro without medical advice, as stopping suddenly may affect your weight and other health conditions. Your prescriber can assess whether the mood change is related to the medication and discuss options with you.
Will my GP ask about mental health before prescribing Mounjaro?
Yes. Any prescriber assessing you for Mounjaro will ask about your mental health history, current mood, and any past depression or anxiety. This is a standard part of the clinical assessment to ensure the medication is safe for you.
Is there a difference between depression from Mounjaro and depression from weight loss?
gradual weight management can affect mood, energy, and self-image — this may feel like depression but may reflect adjustment to physical changes. Mounjaro-related mood changes would be a direct medication effect. Your prescriber can help distinguish between the two and provide appropriate support.
Can I take Mounjaro if I'm already taking antidepressants?
Many people take Mounjaro alongside antidepressants safely. You must inform your prescriber of all current medications before starting Mounjaro. They will assess potential interactions and monitor you throughout treatment to ensure both medications work safely together.
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.