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 considering Mounjaro (tirzepatide) for weight management and currently using Depo Provera for contraception, it's important to understand how these medications interact. Mounjaro may affect how your body absorbs oral medications, but Depo Provera is an injection, not an oral contraceptive. This guide explains the interaction, contraceptive reliability, and what your GP or prescriber needs to know before starting Mounjaro treatment.
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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 Contraception
Mounjaro and oral contraceptives: Mounjaro can slow gastric emptying and may reduce the absorption of oral medications taken at the same time. This is why the UK prescribing guidance recommends that women taking oral contraceptive pills should add a barrier method (such as condoms) for 4 weeks after starting Mounjaro and for 4 weeks after each dose increase.
Depo Provera is an injection: Unlike oral contraceptives, Depo Provera (medroxyprogesterone acetate) is administered as an intramuscular injection every 12 weeks. It does not depend on stomach absorption, so Mounjaro's effect on gastric emptying does not reduce its contraceptive effectiveness. Depo Provera maintains its contraceptive reliability even when taking Mounjaro.
- Depo Provera works systemically via injection, not oral absorption
- Mounjaro does not interfere with injected contraceptive methods
- No additional contraceptive measures needed when combining Mounjaro with Depo Provera
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.
What to Tell Your Prescriber
Before starting Mounjaro, inform your GP or online prescriber that you use Depo Provera as your contraceptive method. This is important for your medical assessment and ensures your prescriber can confirm there are no contraindications. Depo Provera does not affect Mounjaro's eligibility or dosing, but your prescriber needs a complete picture of your medications and contraceptive method.
If you also take any other medications — particularly oral ones — discuss these too, as Mounjaro may affect their absorption. Likewise, some medications can interact with weight loss injections. Your prescriber will assess suitability based on your full medical history. Use our free GLP-1 weight loss calculator to explore Mounjaro dosing information while you arrange a clinical assessment.
- 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.
Will Mounjaro reduce how well Depo Provera works?
No. Depo Provera is an injection and is not affected by Mounjaro's effect on stomach absorption. It remains fully effective as contraception. Mounjaro only affects oral medications, not injected ones.
Do I need to use extra contraception if I take Mounjaro with Depo Provera?
No. Because Depo Provera is injected, no additional contraceptive measures are needed. Unlike oral pills, Depo Provera's effectiveness is not reduced by Mounjaro.
Should I switch from Depo Provera if I start Mounjaro?
No. Depo Provera is a suitable contraceptive choice while taking Mounjaro. There is no clinical reason to switch. Continue your current Depo Provera schedule as normal.
What if I take oral contraceptive pills instead of Depo Provera?
If you take oral contraceptive pills (not Depo Provera), you should add a barrier method for 4 weeks after starting Mounjaro and after each dose increase, as Mounjaro may reduce pill absorption. Discuss this with your GP or prescriber before starting.
Is there any other interaction between Mounjaro and Depo Provera I should know about?
There are no known direct drug interactions between tirzepatide (Mounjaro) and medroxyprogesterone acetate (Depo Provera). Both are safe to use together. Always tell your prescriber about all medications and contraceptive methods during your clinical 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.