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 Affect Libido And Sexual Function?
Weight loss medications like Mounjaro (tirzepatide) can indirectly affect sexual function and libido, though this is not a direct side effect of the medication itself. Changes in libido are often related to weight loss, hormonal shifts, improved health, or psychological factors rather than tirzepatide acting on the body's reproductive systems. Understanding how Mounjaro may influence sexual health can help you manage expectations and know when to speak with your GP about concerns.
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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.
How Mounjaro Affects The Body And Libido
Mounjaro (tirzepatide) is a prescription-only GIP and GLP-1 receptor agonist that works by regulating appetite and blood sugar levels. It does not directly target sexual function or hormone production. However, several indirect mechanisms may influence libido during treatment:
- Weight loss effects: As you lose weight, hormonal balance often improves, which can enhance sexual desire and function in some people.
- Improved confidence: Weight loss may increase self-esteem and body image, positively affecting sexual interest.
- Better health outcomes: Improved blood pressure, blood sugar control, and cardiovascular health can support erectile and sexual function.
- Fatigue and nausea: Common side effects like tiredness or nausea in early weeks may temporarily reduce libido, but these usually improve as your body adjusts.
- Medication interactions: If you take other medications affecting sexual function, Mounjaro may interact indirectly through its effects on absorption or hormonal balance.
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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.
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When To Speak With Your GP About Sexual Health Changes
If you experience persistent changes in libido or sexual function whilst taking Mounjaro, contact your GP. Discuss whether changes are related to the medication, weight loss, improved health, psychological factors, or other medical conditions. Your GP can review your complete medication list, assess whether dose adjustment might help, and explore other underlying causes. Never stop taking Mounjaro without medical guidance. Sexual health is an important part of overall wellbeing, and your healthcare team is there to support you through weight loss treatment.
Track your overall health progress, including energy levels and how you feel, using our free progress tracker. Monitor changes over time to help your GP understand patterns and make informed decisions about your treatment.
- 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.
Does tirzepatide directly affect sexual function?
No. Mounjaro (tirzepatide) does not directly target sexual function or hormone production. Any changes in libido are typically indirect effects from weight loss, improved health, fatigue from side effects, or psychological factors rather than the medication itself acting on sexual systems.
Can Mounjaro cause erectile dysfunction?
Erectile dysfunction is not listed as a direct side effect of Mounjaro. However, early side effects like fatigue and nausea may temporarily reduce sexual interest. Weight loss and improved cardiovascular health often improve erectile function. If concerns persist, speak with your GP.
Will weight loss from Mounjaro improve my sex life?
Many people report improved sexual function and confidence after weight loss, due to better hormonal balance, improved cardiovascular health, and increased self-esteem. Individual experiences vary. Improved blood sugar control and blood pressure from Mounjaro may also support sexual health.
Is it safe to take Mounjaro if I'm concerned about libido changes?
Yes, Mounjaro is safe for most eligible adults. If you're concerned about libido, discuss this with your GP before starting. Your prescriber can monitor you during treatment and adjust your dose or explore other factors if changes occur.
Should I stop Mounjaro if my libido decreases?
No. Never stop Mounjaro without medical guidance. Contact your GP to discuss libido changes. They can assess whether effects are temporary (side effects often improve after weeks 1–4), related to weight loss benefits, or caused by other factors requiring investigation.
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.