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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Can Mounjaro Cause Vertigo? What You Need to Know
Yes, vertigo and dizziness can occur with Mounjaro, though it's not listed as a very common side effect. Dizziness is reported in clinical trials as a common side effect affecting up to 1 in 10 people. If you're comparing Mounjaro with Wegovy, both GLP-1 and dual GIP/GLP-1 medications can cause dizziness. This guide explains what the evidence shows, how the two injections compare, and when to contact your GP. Use our free GLP-1 weight loss calculator to explore how these medications might work for you.
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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.
Mounjaro vs Wegovy: Dizziness and Vertigo Comparison
Both Mounjaro (tirzepatide) and Wegovy (semaglutide) can cause dizziness as a side effect, though vertigo specifically is less common. In the SURMOUNT clinical trials for Mounjaro, dizziness was reported in clinical trial data. Wegovy shows similar patterns in STEP trial data. The difference in mechanism matters: Mounjaro is a dual GIP and GLP-1 receptor agonist, whilst Wegovy is a GLP-1 agonist only. This dual action may affect blood pressure and glucose regulation differently, but both can cause dizziness through similar pathways — slowed gastric emptying, reduced calorie intake, and changes in blood sugar regulation.
- Mounjaro (tirzepatide): Dizziness reported as common side effect; typically improves with continued use or dose adjustment
- Wegovy (semaglutide): Dizziness also reported; usually resolves within weeks as the body adapts to the injection
- Onset: Most commonly appears in the first few weeks of starting or after a dose increase
- Management: Staying hydrated, eating regular meals, and rising slowly from sitting or lying down can help reduce dizziness
Your prescriber can advise on dose titration if dizziness is bothersome.
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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 Seek Medical Help and Individual Suitability
Contact your GP immediately if you experience severe dizziness, vertigo that doesn't improve, fainting, or vision changes — these could signal a more serious condition unrelated to the injection. Mild dizziness that improves within a few days is common and usually settles. Both Mounjaro via KwikPen and Wegovy require a UK prescription following a clinical assessment. Your prescriber will review your full medical history, blood pressure, and other medications to determine which injection is more suitable for you. Neither medication is suitable if you have a history of severe vertigo or balance disorders without specialist medical clearance.
- 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 vertigo a common side effect of Mounjaro compared to Wegovy?
Dizziness is common to both medications (affecting up to 1 in 10 people), but severe vertigo is uncommon. SURMOUNT and STEP trial data show dizziness rates are similar between Mounjaro and Wegovy. Most cases resolve within the first few weeks as your body adjusts to the injection. If dizziness persists, inform your prescriber.
Can Mounjaro dose titration reduce dizziness?
Yes. Starting with a lower dose and increasing gradually — as with standard Mounjaro dose titration — can help minimise dizziness. Your prescriber may slow the titration schedule if you experience bothersome dizziness, allowing your body more time to adapt to each dose level.
What should I do if I feel dizzy after a Mounjaro injection?
Stay hydrated, eat regular small meals, avoid sudden position changes, and rest if needed. Dizziness typically improves within a few days. If it's severe, persistent, or accompanied by chest pain or fainting, contact your GP or NHS 111 immediately. Your prescriber can review whether continuing treatment is appropriate.
Does Wegovy cause fewer balance problems than Mounjaro?
Clinical trial data shows similar dizziness rates for both medications. The choice between them depends on your eligibility, medical history, and how your body responds. Both require a UK prescription and clinical assessment. Your GP or prescriber will advise which is more suitable based on your individual health profile.
Can I take both Mounjaro and Wegovy to compare side effects?
No. You should only take one weight loss injection at a time, under prescription from a UK-licensed prescriber. Combining them would not be clinically appropriate and could increase side effect risk. If one causes unacceptable dizziness, your prescriber can switch you to the other after an appropriate washout period.
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.