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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Mounjaro and Depression — What UK Patients Should Know
Mounjaro (tirzepatide) is a prescription-only weight management injection licensed in the UK. Some people taking GLP-1 and GIP/GLP-1 medications report mood changes or depression-like symptoms. This guide explains what the evidence shows, NHS prescribing context, and when to speak with your GP. It's important to understand both the benefits and potential risks before starting any weight loss medication.
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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 Clinical Evidence Show About Mounjaro and Mood?
Mounjaro's clinical trials (SURMOUNT studies) recorded mood changes in a small percentage of users, though depression was not identified as a primary safety concern in the main trial data. However, post-market reports and real-world use have documented cases of depression, anxiety, and emotional changes in some people taking tirzepatide and other GLP-1 medications.
- In SURMOUNT-1, depression was reported in approximately 2–3% of participants taking Mounjaro versus 1–2% in the placebo group
- The mechanism is not fully understood — it may relate to gradual weight management, metabolic changes, or the medication's effect on neurotransmitters
- Individual responses vary significantly; most people do not experience mood changes
- The MHRA continues to monitor this and has included mood disorders in the product information
If you experience new or worsening depression whilst on Mounjaro, contact your GP or prescriber immediately — do not stop the medication without guidance.
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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.
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NHS Prescribing, Monitoring, and What to Discuss With Your GP
In the UK, Mounjaro is prescribed through NHS specialist tier 3 weight management services or privately following a clinical assessment. Your GP or prescriber should discuss mental health history before starting treatment — those with untreated depression or significant mental health conditions may need additional monitoring or alternative options.
The NHS expects prescribers to assess your mental health baseline and monitor for mood changes during treatment. If you develop depression symptoms after starting Mounjaro, your prescriber may adjust your dose, switch you to an alternative medication (such as Wegovy), or pause treatment. Use our free GLP-1 weight loss calculator to understand expected outcomes, and discuss any mental health concerns with your healthcare team before beginning.
[Section 3 content]- 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?
Mounjaro may increase depression risk in some people, though it's relatively rare. Clinical trials showed mood changes in 2–3% of users. The exact mechanism isn't fully understood, but gradual weight management and metabolic changes may contribute. Most people tolerate the medication well. Always inform your GP of any mental health history before starting.
What should I do if I experience depression whilst taking Mounjaro?
Contact your GP or prescriber immediately — do not stop Mounjaro without guidance. They may adjust your dose, switch you to an alternative like Wegovy, or pause treatment. Depression is a serious side effect that requires prompt medical attention and ongoing monitoring throughout your weight loss journey.
Will my GP monitor my mental health if I'm prescribed Mounjaro on the NHS?
Yes, NHS prescribers should assess your mental health baseline before starting Mounjaro and monitor for mood changes during treatment. If you're accessing Mounjaro privately, ensure your prescriber is aware of any mental health conditions or medications, as this affects suitability and monitoring requirements.
Is Mounjaro safe if I have a history of depression?
If you have a history of depression, you're not automatically excluded from Mounjaro, but your prescriber needs to know. They'll assess whether it's safe for you, potentially recommend closer monitoring, or suggest an alternative weight loss approach. Always disclose full mental health history during your clinical assessment.
How does Mounjaro compare to Wegovy regarding depression risk?
Both Mounjaro and Wegovy are GLP-1-based medications and carry similar depression risk profiles. Mounjaro is a dual GIP/GLP-1 agonist, whilst Wegovy is GLP-1 only — individual responses differ. Your prescriber can help decide which is more suitable based on your mental health history and overall clinical picture.
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