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 Cause Thrush?
Thrush (candidiasis) is not listed as a known side effect of Mounjaro (tirzepatide) in UK clinical trials or the official product information. However, any medication that affects digestion or glucose levels may indirectly influence conditions that favour fungal growth. If you develop signs of thrush — such as white patches in your mouth, itching, or unusual discharge — whilst taking Mounjaro, it's important to discuss this with your GP, as it may be unrelated to the injection itself. Our free GLP-1 weight loss calculator can help you understand potential health changes during treatment.
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.
How Mounjaro Works and Why Infections May Occur
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist — it works by activating two natural hormone pathways to help regulate appetite and blood sugar. Unlike medications that directly suppress the immune system, tirzepatide does not have a known immunosuppressive effect. However, GLP-1 medications can slow gastric emptying (how quickly food moves through your stomach), which may temporarily alter gut bacteria balance. Additionally, if Mounjaro helps improve blood sugar control in people with prediabetes or type 2 diabetes, this is generally protective against thrush — high blood sugar levels create an environment where Candida fungi thrive. If you develop thrush whilst on Mounjaro, it is more likely to be coincidental rather than directly caused by the injection. Always inform your GP of all medications you are taking, as other medicines or underlying conditions may increase thrush risk.
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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.
What to Do If You Suspect Thrush While Taking Mounjaro
If you notice symptoms of thrush — oral white patches, vaginal itching or discharge, redness around the genitals, or unusual nappy rash in infants — contact your GP promptly. Do not stop taking Mounjaro without consulting your healthcare provider. Thrush is treatable with antifungal medications (such as fluconazole or topical creams), and your GP can prescribe these whilst you continue your weight management treatment. Keep a record of when symptoms started and any other changes since beginning Mounjaro — this helps your GP assess whether the thrush is related to the injection or another cause. Our progress tracker can help you log health changes during your treatment journey.
- 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 thrush a common side effect of Mounjaro?
No. Thrush is not listed as a common or uncommon side effect of Mounjaro in UK clinical trials. The most common side effects are nausea, diarrhoea, vomiting, and constipation. However, any new symptom should be discussed with your GP to rule out other causes.
Can GLP-1 injections like Mounjaro increase infection risk?
GLP-1 medications do not suppress the immune system. However, they can affect digestion and gastric emptying. If Mounjaro improves blood sugar control, this actually reduces thrush risk — high glucose levels favour fungal growth. If thrush occurs, it's likely unrelated to the injection.
What should I do if I get thrush while taking Mounjaro?
Contact your GP. Thrush is easily treatable with antifungal medication. Do not stop Mounjaro without advice. Your GP can prescribe antifungals (fluconazole, clotrimazole cream) whilst you continue treatment. Report any symptoms to help identify the underlying cause.
How does Mounjaro differ from Wegovy in terms of side effects?
Mounjaro (tirzepatide) is a dual GIP and GLP-1 agonist, whilst Wegovy (semaglutide) is a GLP-1 agonist only. Both have similar common side effects (nausea, diarrhoea, constipation). Neither has thrush listed as a known side effect. Mounjaro may cause slightly different gastric effects due to its dual mechanism.
When should I be concerned about thrush symptoms while on Mounjaro?
Seek medical advice if symptoms persist beyond a few days, worsen, or are accompanied by fever or other signs of infection. Thrush itself is not dangerous but can be uncomfortable. Early treatment with antifungals is effective. Contact your GP if unsure — they can assess whether symptoms are thrush or another condition.
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.