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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10mg Mounjaro Side Effects — Complete UK Guide
At the 10mg dose, Mounjaro (tirzepatide) is a maintenance or escalation dose used in UK weight management treatment. Most side effects are gastrointestinal — nausea, diarrhoea, and constipation are most common. Many side effects ease over time as your body adjusts, but it's important to know what to expect and when to contact your GP. This guide explains the most likely side effects at 10mg and when to seek medical attention.
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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 10mg Mounjaro
At the 10mg dose, the majority of people experience gastrointestinal side effects, particularly during the first 4–8 weeks after escalation. These may include:
- Nausea — the most frequently reported side effect; may last several days after injection
- Diarrhoea — loose stools occurring in up to 1 in 10 people
- Constipation — affecting similar numbers; can alternate with diarrhoea
- Stomach pain or discomfort — usually mild to moderate
- Indigestion — acid reflux or heartburn after meals
- Fatigue — tiredness or low energy levels
- Injection site reactions — redness, bruising, or mild pain where you inject
These side effects typically improve within 1–2 weeks of your body adjusting to the dose. Staying hydrated, eating smaller meals, and avoiding fatty foods can help. Our GLP-1 weight loss calculator can help you understand what to expect at different doses, and our BMI calculator tracks your overall health context alongside treatment.
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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
Whilst most side effects are mild, contact your GP or NHS 111 immediately if you experience:
- Severe, persistent stomach pain spreading to your back — possible sign of pancreatitis
- Serious allergic reaction — swelling of lips, tongue, face, or throat; difficulty breathing
- Severe vomiting that prevents you keeping fluids down
- Jaundice — yellowing of skin or eyes, pale stools, or dark urine
- Gallbladder pain — sharp pain in the upper right stomach area
- Rapid or irregular heartbeat — palpitations or chest discomfort
These are rare but serious. If you have concerns about any symptoms, contact your prescriber or GP — do not wait. Your healthcare team can adjust your dose or provide additional support if side effects are affecting your quality of life.
- 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 long do 10mg Mounjaro side effects last?
Most gastrointestinal side effects peak in the first 1–2 weeks after escalating to 10mg and gradually improve over 3–4 weeks as your body adjusts. Nausea is often the first to improve. Some people experience minimal side effects; others may have symptoms for 4–8 weeks. If side effects persist beyond 8 weeks or worsen, contact your GP.
Can I reduce my Mounjaro dose if side effects are severe?
Yes. If you experience intolerable side effects at 10mg, contact your prescriber immediately. They may temporarily reduce you to 7.5mg, give your body more time to adjust, then escalate more slowly. Never skip doses or reduce without medical guidance — consistent dosing works best for weight management.
What's the difference between 10mg Mounjaro and Wegovy side effects?
Mounjaro is a dual GIP/GLP-1 agonist; Wegovy (semaglutide) is a GLP-1 agonist only. Both cause similar side effects — nausea, diarrhoea, constipation. Mounjaro's dual mechanism may produce slightly stronger appetite suppression. Individual side effect profiles vary; what affects one person minimally may affect another more noticeably.
Does nausea mean Mounjaro is working?
Not necessarily. Nausea is a common side effect of GLP-1 and GIP activation — it reflects how the medication is working in your body — but it does not mean weight loss will be better or worse. Many people lose weight without nausea, and some experience nausea but minimal weight loss. Side effects and efficacy are separate.
Are there ways to manage 10mg Mounjaro side effects at home?
Yes. Eat smaller, frequent meals; avoid greasy or fatty foods; stay well hydrated; take ginger tea or peppermint for nausea; increase fibre gradually for constipation; get adequate sleep. Over-the-counter anti-nausea remedies (ginger supplements, acupressure bands) may help. Always inform your GP of any over-the-counter medicines you're taking alongside Mounjaro.
Ready to take control of your weight loss journey?
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