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 or Anxiety?
Mounjaro (tirzepatide) is a prescription-only weight management injection licensed in the UK. Mental health concerns, including depression and anxiety, are not listed as common side effects in clinical trials or the product information. However, gradual weight management itself, hormonal changes, and individual responses to any medication can affect mood. This guide explains what the evidence shows, when to contact your GP, and how mental health is monitored if you're prescribed Mounjaro through NHS tier 3 services or private assessment.
10,000+ calculations today · NHS-aligned thresholds · 100% free
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 Does the Evidence Show About Mounjaro and Mental Health?
Clinical trials of Mounjaro (the SURMOUNT studies) did not identify depression or anxiety as common or very common side effects. The MHRA-approved summary of product characteristics lists mood changes as uncommon — affecting fewer than 1 in 100 people. However, this does not mean mood effects cannot occur.
Mood changes can happen for several reasons:
- gradual weight management can trigger emotional responses, even when desired
- Hormonal changes during significant weight change may affect mood regulation
- Underlying depression or anxiety may become more noticeable as appetite-suppressing effects wear off week-to-week
- Individual differences in how the body responds to GIP and GLP-1 receptor activation
If you experience persistent low mood, anxiety, or thoughts of self-harm, contact your GP or the Samaritans (116 123) immediately — do not wait for your next appointment.
Clinically BackedWeight Loss
No appointments. No waiting rooms. Just care — from a UK-regulated online pharmacy.
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.
NHS Monitoring and Private Prescribing Safeguards
If Mounjaro is prescribed through NHS tier 3 specialist weight management services, mental health screening is part of the standard assessment. Your prescriber will discuss mood history, current mental health support, and any concerns before starting treatment.
For private prescribing, a UK-licensed prescriber must conduct an online clinical assessment that includes mental health history. You should be asked about current mood, any history of depression or anxiety, and medications you're taking — especially antidepressants or anti-anxiety drugs.
Both routes require you to report side effects, including mood changes, within the first 4–8 weeks. If you notice changes in mood after starting, contact your prescriber or GP immediately rather than stopping the injection without guidance.
- 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?
Depression is not listed as a common side effect in Mounjaro clinical trials. The MHRA notes mood changes as uncommon (less than 1 in 100 people). However, gradual weight management, hormonal shifts, and individual variation can affect mood. Any persistent low mood should be reported to your GP or prescriber immediately.
What's the difference between Mounjaro and Wegovy regarding mental health?
Both Mounjaro (tirzepatide) and Wegovy (semaglutide) list mood changes as uncommon side effects. The clinical evidence for depression or anxiety is similar between the two — low reported rates in trials. Individual experiences vary. Your prescriber can discuss which option suits your health profile.
Should I tell my GP if I have a history of depression before starting Mounjaro?
Yes, absolutely. Mental health history — including depression, anxiety, bipolar disorder, or any mood disorder — must be disclosed to your prescriber or NHS tier 3 team. This helps them assess whether Mounjaro is suitable for you and plan appropriate monitoring during treatment.
What should I do if I notice anxiety or low mood after starting Mounjaro?
Contact your GP or prescriber immediately. Do not stop the injection without guidance. They will assess whether symptoms are related to Mounjaro, the dose, underlying factors, or something else — and adjust your care plan accordingly. Support is available.
Are there mental health support resources in the UK while on Mounjaro?
Yes. Your GP can refer you to NHS talking therapies (IAPT services) or counselling. Samaritans (116 123) offer 24/7 crisis support. Mind (0300 123 3393) provides mental health advice. If prescribed privately, ask your provider about mental health support pathways alongside weight management.
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.