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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Endometriosis and Mounjaro: What You Need to Know
Endometriosis is a chronic condition where tissue similar to the uterine lining grows outside the uterus, affecting approximately 10% of women of reproductive age in the UK. Many women with endometriosis struggle with weight management, which can complicate the condition. Mounjaro (tirzepatide) is a prescription-only injection licensed for weight management in UK adults. If you have endometriosis and are considering weight loss treatment, it's important to understand how Mounjaro works, its potential effects on your condition, and how to access it safely through the NHS or private prescribing routes.
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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.
Weight Management, Endometriosis, and Mounjaro in the UK
Women with endometriosis often experience pain, irregular periods, and fertility challenges, and excess weight can worsen symptoms and increase inflammation. Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist — meaning it works on two natural hormone pathways to help reduce appetite and support weight management. Unlike Ozempic or Wegovy, Mounjaro's dual mechanism may provide additional benefits for metabolic health.
If you have endometriosis and are considering Mounjaro, several important factors apply:
- Medication interactions: Mounjaro may slow gastric emptying, which could affect how other medications are absorbed. If you take pain relief or hormonal treatments for endometriosis, your prescriber needs to know.
- Nausea and digestive effects: Mounjaro commonly causes nausea, vomiting, and constipation — symptoms many women with endometriosis already experience. This could worsen early on.
- Fertility considerations: If you are planning to conceive, Mounjaro is not suitable. Oral contraceptives (often used to manage endometriosis) may also be affected by Mounjaro's effect on absorption.
- NHS access: You must have a BMI of 30 or above (or 27–29.9 with weight-related health conditions) and be referred to a specialist tier 3 weight management service by your GP.
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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.
NHS and Private Routes for Mounjaro in the UK
NHS route: If eligible, ask your GP to refer you to your local NHS specialist weight management service (tier 3). However, NHS capacity is extremely limited, and waiting lists can be months to years in many regions. Your GP can also discuss your endometriosis with the weight management team to ensure safe prescribing.
Private route: You can access Mounjaro through a GPhC-registered online pharmacy following a consultation with a UK-licensed prescriber. This avoids NHS waiting lists but requires private payment (typically £200–£320 per month depending on dose). A private prescriber will still assess your medical history, including your endometriosis diagnosis and current medications, before issuing a prescription.
Check our free BMI calculator above to determine if you meet eligibility criteria, and try our GLP-1 weight loss calculator to see projected weight loss outcomes at different Mounjaro dose levels.
- 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 I take Mounjaro if I have endometriosis?
Mounjaro may be suitable if you meet weight management eligibility criteria (BMI ≥30 or ≥27 with comorbidities). However, you must disclose your endometriosis diagnosis and current medications to your prescriber. Mounjaro's effects on nausea, constipation, and medication absorption need careful consideration alongside your endometriosis treatment plan.
Will Mounjaro help relieve endometriosis pain?
Mounjaro is not a treatment for endometriosis itself. However, if excess weight worsens your endometriosis symptoms or inflammation, modest weight loss (5–10% of body weight) may help reduce pain and improve symptom severity. Any weight loss benefit is indirect, not a direct effect of tirzepatide.
Does Mounjaro affect fertility if I have endometriosis?
Mounjaro is not recommended if you are planning to become pregnant. If you take oral contraceptives to manage endometriosis, Mounjaro may reduce their effectiveness — additional barrier contraception is needed for 4 weeks after starting or dose increases. Always discuss fertility plans with your prescriber.
Can I take Mounjaro while on endometriosis medications?
Mounjaro may interact with some medications by slowing stomach emptying and reducing absorption of oral medicines. If you take hormonal treatments, pain relief, or other medications for endometriosis, inform your GP or prescriber. They can check for interactions and adjust timing if needed.
How do I access Mounjaro on the NHS if I have endometriosis?
Ask your GP to refer you to your local NHS tier 3 specialist weight management service. You must meet eligibility criteria (BMI ≥30 or ≥27–29.9 with weight-related health conditions). The specialist team will review your medical history, including endometriosis, before assessing suitability. Private access is also available but requires payment and private prescriber assessment.
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.