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
Can Mounjaro Make You Dizzy?
Yes, dizziness is a recognised side effect of Mounjaro (tirzepatide), though it is not extremely common. In clinical trials, some people experienced dizziness when starting or adjusting their dose. This is usually mild and tends to improve as your body adjusts. However, dizziness can occasionally signal a more serious issue, so it is important to understand when to contact your GP. This guide explains what NHS guidance says about Mounjaro and dizziness, why it happens, and what to do if you experience it.
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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.
Why Does Mounjaro Cause Dizziness?
Dizziness with Mounjaro can occur through several mechanisms. Nausea and stomach upset are very common side effects, and nausea itself can trigger dizziness or vertigo in some people. Blood sugar changes may also contribute — if you are already taking diabetes medication, Mounjaro can lower blood sugar further, and low blood sugar can cause dizziness, shakiness, and fatigue. Dehydration is another factor; gastrointestinal side effects like diarrhoea and vomiting can lead to fluid loss, which reduces blood volume and may cause lightheadedness. Additionally, Mounjaro slows gastric emptying (how quickly food leaves your stomach), which can affect nutrient absorption and blood pressure regulation. Most dizziness related to Mounjaro is mild and improves within days or weeks as your body adapts to the medication.
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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.
When to Contact Your GP About Dizziness
Contact your GP immediately if dizziness is severe, persistent, or accompanied by chest pain, shortness of breath, or fainting. These could indicate a more serious issue such as a change in heart rate or blood pressure that requires urgent assessment. You should also seek advice if dizziness persists beyond the first few weeks of treatment or after a dose increase, or if it worsens despite staying hydrated and resting. Your GP may adjust your Mounjaro dose, recommend dietary or hydration strategies, or investigate whether other medications or health conditions are contributing. Never stop taking Mounjaro without speaking to your prescriber first — they can guide you safely through managing side effects or switching treatments if needed.
- 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.
Is dizziness a common side effect of Mounjaro?
Dizziness is listed as a common side effect in clinical trials, though it is less common than nausea, constipation, or diarrhoea. Most people who experience dizziness find it mild and temporary. It is more likely when starting Mounjaro or increasing the dose (dose titration) and typically improves within the first few weeks as your body adjusts.
How can I reduce dizziness when taking Mounjaro?
Stay well hydrated — drink water throughout the day, especially if you have diarrhoea or vomiting. Eat small, frequent meals to stabilise blood sugar and nutrient intake. Rise slowly from sitting or lying down to avoid postural dizziness. If you are taking diabetes medication alongside Mounjaro, your GP may need to adjust your diabetes dose to prevent low blood sugar. Rest and avoid driving or operating machinery if you feel unsteady.
Is dizziness with Mounjaro different from dizziness with Wegovy?
Both Mounjaro (tirzepatide) and Wegovy (semaglutide) can cause dizziness as both are GLP-1 receptor agonists or, in Mounjaro's case, a dual GIP/GLP-1 agonist. The mechanisms are similar — nausea, blood sugar changes, and dehydration. Individual experiences vary, and some people may tolerate one medication better than the other. Your prescriber can discuss which option might suit you best.
Can Mounjaro cause vertigo or balance problems?
True vertigo (spinning sensation) is not a typical side effect of Mounjaro, though dizziness and lightheadedness can occur. If you experience spinning sensations, severe balance problems, or nausea with head movements, contact your GP to rule out other causes such as inner ear issues or medication interactions. Do not assume vertigo is caused by Mounjaro without professional assessment.
Should I stop taking Mounjaro if I feel dizzy?
No — do not stop taking Mounjaro without consulting your prescriber, even if you feel dizzy. Stopping abruptly can cause other complications. Contact your GP or the prescriber who issued your Mounjaro KwikPen to discuss your symptoms. They can advise whether to continue, adjust the dose, manage symptoms with lifestyle changes, or switch to an alternative medication. Always seek professional guidance first.
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