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 7.5mg Side Effects — What to Expect
Mounjaro (tirzepatide) is a prescription-only weight management injection licensed in the UK. At the 7.5mg dose, which is typically used during dose escalation, side effects are common but usually manageable. Most people experience digestive symptoms like nausea or constipation, particularly when first starting or increasing their dose. Understanding what to expect can help you decide whether this medication is right for you and when to contact your GP. Side effects often improve after the first few weeks as your body adjusts.
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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.
Common Side Effects at 7.5mg Dose
At the 7.5mg dose, nausea remains the most frequently reported side effect, though many people find it less severe than when they first started the medication. Gastrointestinal symptoms are most common and may include diarrhoea, constipation, stomach pain, and indigestion. Some people also experience fatigue, dizziness, headaches, or mild hair loss (alopecia). Injection site reactions such as redness, bruising, or mild pain at the injection point are normal and typically resolve within a few hours.
- Nausea and vomiting — usually temporary and manageable
- Digestive changes — diarrhoea or constipation
- Appetite suppression — expected and therapeutic effect
- Fatigue or dizziness — usually mild and short-lived
- Injection site reactions — redness or bruising at pen site
The 7.5mg dose is a middle escalation point in the tirzepatide dose titration schedule. If side effects are severe, your prescriber may keep you at this dose longer before increasing further, or may adjust your dietary approach to manage symptoms better.
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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 Seek Medical Attention
While most side effects are mild, contact your GP or prescriber immediately if you experience severe, persistent stomach pain spreading to your back — this could indicate pancreatitis. Seek urgent help if you develop a serious allergic reaction (swelling of face, lips, tongue, or throat), severe vomiting that prevents you keeping food or fluids down, or changes in your vision. These serious side effects are rare but require prompt medical assessment. For ongoing nausea or digestive problems, contact your prescriber rather than stopping the medication suddenly — they can advise on timing adjustments or dietary changes to help manage symptoms whilst you continue 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.
How does the 7.5mg dose compare to other Mounjaro doses for side effects?
Side effects follow a dose-dependent pattern — 5mg typically causes fewer side effects than 7.5mg, which causes fewer than 10mg or 15mg. However, individual variation is significant; some people tolerate 7.5mg very well whilst others experience more symptoms at lower doses. Your prescriber will monitor your response and adjust accordingly.
How long do Mounjaro side effects last at 7.5mg?
Most side effects peak during the first few days after injection, then gradually improve over the following week. When you first reach 7.5mg, you may notice increased symptoms for 2–3 weeks, but many people adapt well by weeks 4–6. If severe symptoms persist beyond 3 weeks, contact your prescriber.
Can I reduce nausea on Mounjaro 7.5mg without stopping the medication?
Yes. Try eating smaller, more frequent meals, avoiding fatty or spicy foods, staying well hydrated, and taking your injections on an evening. Your prescriber might also recommend ginger supplements or anti-nausea medication temporarily. Never adjust your dose without guidance from your prescriber.
Is Mounjaro 7.5mg safer than Wegovy at equivalent doses?
Both Mounjaro and Wegovy have similar side effect profiles, though Mounjaro's dual GIP/GLP-1 mechanism may produce slightly different symptoms. Mounjaro 7.5mg is roughly equivalent to Wegovy 1mg in terms of side effects. Individual tolerability varies; your GP or prescriber can advise which is more suitable for you.
What should I do if side effects at 7.5mg are unbearable?
Contact your prescriber immediately. Options include staying at your current dose longer, returning to a lower dose, adjusting meal timing, or switching to a different medication. Never stop abruptly — your prescriber will guide a safe approach. Use our free GLP-1 weight loss calculator to discuss realistic expectations with your healthcare team.
Ready to take control of your weight loss journey?
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