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
Can Mounjaro Make You Depressed?
Depression is not listed as a common side effect of Mounjaro (tirzepatide) in UK clinical trials or MHRA safety data. However, some people report mood changes when taking weight loss medications. This guide explains what the evidence shows, how to monitor your mental health whilst on Mounjaro, and when to contact your GP if you have concerns about your mood or emotional wellbeing during treatment.
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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 Does the Evidence Show About Mounjaro and Mood?
Clinical trial data from SURMOUNT studies (the main UK trials for Mounjaro/tirzepatide) did not identify depression as a frequent side effect. Common side effects reported were gastrointestinal — nausea, diarrhoea, constipation, and vomiting — rather than mood-related symptoms.
However, mood changes can occur with any significant health intervention, including weight loss medication. Possible reasons include:
- gradual weight management — sudden changes in body composition can affect hormone levels and self-image
- Medication side effects — nausea and digestive issues can reduce appetite and energy, affecting mood indirectly
- Blood sugar changes — tirzepatide affects glucose regulation, which influences energy and mood
- Underlying conditions — pre-existing depression or anxiety may become more noticeable as other symptoms improve
The NHS emphasises that individual experiences vary considerably. If you develop low mood or depressive symptoms whilst on Mounjaro, this should be discussed with your GP rather than assumed to be a direct effect of the medication.
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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.
When to Speak to Your GP About Mood Changes
Contact your GP if you experience persistent sadness, loss of interest in activities, sleep problems, fatigue, or difficulty concentrating whilst taking Mounjaro. These warrant a medical review to determine whether they are related to the medication, the rapid weight changes, or an underlying condition.
Your prescriber or GP can:
- Assess whether symptoms are medication-related or separate
- Review your tirzepatide dose or consider adjusting it
- Discuss mental health support or referral to specialist services if needed
- Explore whether dose titration or a temporary pause might help
Never stop Mounjaro suddenly without medical guidance. Open communication with your healthcare team ensures safe, supportive treatment.
- 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 depression listed as a side effect of Mounjaro on the MHRA information sheet?
Depression is not listed as a common or very common side effect in MHRA-approved safety information for Mounjaro (tirzepatide). The most frequently reported side effects are gastrointestinal — nausea, diarrhoea, vomiting, and constipation. If you experience low mood, report it to your GP for assessment.
Can weight loss itself affect mood and mental health?
Yes, gradual weight management can trigger both positive and challenging emotional responses. Some people feel more energised and confident; others experience fatigue, hormone shifts, or emotional adjustment to body changes. These are separate from direct medication effects but worth monitoring and discussing with your healthcare team.
What should I do if I feel depressed whilst taking Mounjaro?
Contact your GP or the prescriber who issued your Mounjaro KwikPen. Describe your symptoms clearly — when they started, how long they last, and how they affect daily life. Your GP can assess whether the symptoms are medication-related, dose-dependent, or a separate health issue requiring mental health support.
Can Mounjaro be stopped if it's affecting my mood?
Never stop Mounjaro suddenly without medical advice. Your GP or prescriber can discuss adjusting your tirzepatide dose, pausing treatment temporarily, or switching to an alternative if mood changes are concerning. Abrupt discontinuation is not recommended and may cause other issues.
Is Mounjaro safe for people with depression or anxiety?
People with a history of depression can take Mounjaro, but it requires careful monitoring. Your GP or prescriber needs to know about any mental health conditions before starting. Regular check-ins help ensure the medication suits you and that any mood changes are managed appropriately and safely.
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.