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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Is Dizziness a Side Effect of Mounjaro?
Dizziness can occur when taking Mounjaro (tirzepatide), though it is not one of the most common side effects. It may happen during the initial weeks of treatment or when your dose increases, typically related to changes in appetite, blood sugar levels, or how quickly your body adjusts to the medication. If you experience dizziness with Mounjaro, it is important to understand what might be causing it and when to contact your GP for advice. This guide explains dizziness as a potential side effect, how to manage it safely, and what steps to take if it persists.
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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.
Why Does Mounjaro Cause Dizziness?
Dizziness with Mounjaro can happen for several interconnected reasons. As a dual GIP and GLP-1 receptor agonist, Mounjaro alters how your body regulates blood sugar and appetite. When blood sugar drops too quickly (hypoglycaemia), dizziness is a common symptom. The medication also slows gastric emptying—how quickly food leaves your stomach—which can temporarily affect blood pressure and cause lightheadedness.
Dehydration is another significant factor. Many people on Mounjaro experience nausea, vomiting, or diarrhoea, which can lead to fluid loss and contribute to dizziness. Additionally, if you are not eating enough calories to match the medication's appetite-suppressing effects, your blood sugar and energy levels may drop, triggering dizziness or faintness.
Dose titration matters too. When you first start Mounjaro or increase your KwikPen dose, your body needs time to adjust. Starting at 2.5 mg and gradually escalating through 5 mg, 7.5 mg, 10 mg, 12.5 mg, and finally 15 mg allows your system to adapt—dizziness is more common during these transition weeks.
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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 Help and How to Manage It
Mild, occasional dizziness that resolves within a few days of starting or increasing your dose is generally not a cause for alarm. However, you should contact your GP immediately if dizziness is severe, persistent, accompanied by chest pain, vision changes, or fainting episodes—these may indicate a more serious condition.
To manage dizziness safely, stay well hydrated by drinking water regularly throughout the day, even if you do not feel thirsty. Eat small, balanced meals to maintain stable blood sugar—skipping meals worsens dizziness risk. Stand up slowly after sitting or lying down to prevent orthostatic dizziness. If dizziness is severe, ask your prescriber whether pausing your dose or slowing your titration schedule might help. Never stop Mounjaro abruptly without medical guidance. Keep a progress log of when dizziness occurs to share with your GP, and use our free progress tracker to record how you feel each week.
- 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 common with Mounjaro?
Dizziness is not listed as a very common or common side effect in UK clinical data, but it does occur in some people, particularly during dose increases or if dehydration or low blood sugar develops. Most cases resolve within days as your body adjusts.
Can Mounjaro cause low blood sugar (hypoglycaemia)?
Mounjaro itself does not directly cause hypoglycaemia in people without diabetes. However, if you are also taking insulin or other diabetes medications, your prescriber may need to adjust those doses. Rapid blood sugar changes can trigger dizziness. Always inform your GP of all medications.
What is the difference between Mounjaro and Wegovy for dizziness risk?
Mounjaro is a dual GIP and GLP-1 agonist, while Wegovy (semaglutide) is a GLP-1 agonist only. Both can cause dizziness, though the mechanisms are similar. Mounjaro may have a slightly different side effect profile due to its dual action, but individual responses vary significantly.
Should I stop taking Mounjaro if I feel dizzy?
Do not stop Mounjaro without medical guidance. Contact your GP or prescriber to discuss your symptoms. They may suggest staying at your current dose longer, slowing your titration schedule, adjusting your diet, or increasing hydration before considering stopping.
How long does dizziness last when starting Mounjaro?
Most adjustment-related dizziness resolves within 1–2 weeks as your body acclimates. If it persists beyond this, or worsens, contact your GP. Persistent dizziness may indicate dehydration, inadequate nutrition, or another underlying issue requiring medical assessment.
Ready to take control of your weight loss journey?
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