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 Depo Provera — What You Need to Know
If you're taking Depo Provera and considering Mounjaro for weight management, it's important to understand how these medications interact. Mounjaro (tirzepatide) is a prescription-only GIP and GLP-1 receptor agonist licensed in the UK for weight management in eligible adults. Because Mounjaro can affect how your body absorbs other medications, including hormonal contraceptives, you should always inform your GP or prescriber if you're using any form of contraception. This guide explains the interaction and what UK NHS guidance recommends.
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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 Affects Hormonal Contraceptives
Mounjaro can slow gastric emptying — the rate at which food and medications leave your stomach. This means oral medications, including hormonal contraceptives taken by mouth, may be absorbed less effectively while you're taking Mounjaro, particularly during dose increases. However, Depo Provera is administered as an intramuscular injection, not orally, so it bypasses the digestive system entirely and is not affected by gastric emptying delays.
That said, any significant weight loss achieved with Mounjaro may theoretically affect how all medications — including injected contraceptives — are distributed and metabolised in your body, though Depo Provera's efficacy is not considered compromised by this. The key concern is if you're also taking any oral medications alongside Depo Provera, including other tablets or capsules.
- Oral contraceptive pills (if also taken) may need additional barrier contraception for 4 weeks after starting Mounjaro and 4 weeks after each dose increase
- Depo Provera (injection) is not directly affected by Mounjaro's gastric effects
- Always disclose all medications to your prescriber before starting Mounjaro
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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 Guidance and What Your GP Needs to Know
The UK product information for Mounjaro recommends that women using hormonal contraception should add a barrier method (condoms) or switch to a non-hormonal or non-oral contraceptive for 4 weeks after starting Mounjaro and for 4 weeks after each dose increase. Since Depo Provera is neither oral nor a barrier method, your GP may recommend discussing whether additional precautions are necessary for your specific situation.
Book a consultation with your GP or the prescriber managing your Mounjaro treatment to review your contraceptive strategy. They can assess your individual risk and advise whether your current Depo Provera schedule needs adjustment or whether additional contraception is advisable during Mounjaro dose escalation. Calculate your BMI using our free BMI calculator to understand your weight management context when discussing Mounjaro eligibility with your NHS clinician.
- 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 while using Depo Provera?
Yes, Depo Provera (injected) is not directly affected by Mounjaro's effects on gastric emptying. However, you must inform your prescriber of all contraceptive methods. If you also take any oral medications, those may require additional precautions during Mounjaro use.
Will Mounjaro affect how well Depo Provera works?
Depo Provera, being an intramuscular injection, is not absorbed through the digestive system and is not directly compromised by Mounjaro's gastric effects. Significant weight loss may theoretically affect medication distribution, but Depo Provera efficacy is considered robust to this.
Do I need barrier contraception while taking Mounjaro with Depo Provera?
UK product information recommends barrier methods (condoms) or alternative contraception for 4 weeks after starting Mounjaro and after each dose increase. Discuss with your GP whether this applies to your situation given you're using an injected contraceptive.
What should I tell my GP about my contraception when starting Mounjaro?
Disclose your Depo Provera schedule, the dates of your last and next injections, and any other medications you take. This helps your prescriber assess your individual contraceptive risk and advise on any additional precautions needed during Mounjaro dose escalation.
How often should I review my contraception plan while on Mounjaro?
Review at each Mounjaro dose increase and discuss any changes in your menstrual cycle or contraceptive concerns with your GP. Significant weight loss may affect how other medications are metabolised, so ongoing communication with your prescriber is important.
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.