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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Dizzy Spells On Mounjaro — UK Health Information
Dizziness can occur while taking Mounjaro (tirzepatide), though it is not listed as a very common side effect. If you experience dizzy spells during your tirzepatide treatment, it is important to understand what may be causing them and when to contact your GP. This guide explains the potential reasons behind dizziness on Mounjaro, how long symptoms typically last, and practical steps you can take. Always consult your GP or prescriber if dizziness is severe, persistent, or affecting your daily life.
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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 Dizziness May Occur on Mounjaro
Dizziness on Mounjaro can occur for several interconnected reasons. Dehydration is a common culprit — nausea and vomiting (very common side effects of tirzepatide) can lead to fluid loss if you are not drinking enough water. Blood sugar changes may also play a role, especially if you have type 2 diabetes or prediabetes, as Mounjaro works by regulating blood glucose levels. Low blood pressure is possible when starting or increasing your dose, as the medication affects your body's glucose and appetite regulation systems. Additionally, rapid gastric emptying changes — how quickly food leaves your stomach — can affect nutrient absorption and blood sugar stability in the first few weeks of treatment. Finally, fatigue and energy changes (common in the first 4–8 weeks) can contribute to feelings of dizziness or lightheadedness. Individual responses vary significantly depending on dose, overall health, and other medications you may be taking.
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If your BMI suggests you're overweight or obese, explore our GLP-1 calculators to project potential weight loss on Mounjaro or Wegovy.
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When to Seek Medical Help and Management Tips
Contact your GP or prescriber if dizziness is severe, persistent (lasting more than a few days), or worsening — these may signal an underlying issue requiring assessment. Practical steps to reduce dizziness:
- Drink plenty of water throughout the day to stay hydrated
- Eat small, frequent, balanced meals to stabilise blood sugar
- Rise slowly from sitting or lying down to avoid sudden blood pressure drops
- Avoid standing for long periods without movement
- Monitor your blood pressure if you have a home monitor
- Rest in a cool, quiet space if dizziness occurs
- Keep a symptom diary to identify patterns — does it happen at certain times or with specific doses?
Many people find dizziness improves within 2–4 weeks as their body adjusts to tirzepatide. If symptoms persist beyond this window, your prescriber may adjust your dose or investigate other causes.
- 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 not listed as a very common side effect in clinical trials, but it can occur, particularly during dose escalation or in the first few weeks of treatment. It is more likely to be related to dehydration, nausea, or blood sugar changes than to tirzepatide directly. Many people experience improvement as their body adjusts. Use our GLP-1 weight loss calculator to understand what to expect at different Mounjaro doses, and always report persistent dizziness to your prescriber.
Can I reduce dizziness while taking Mounjaro?
Yes. Stay well hydrated, eat balanced meals regularly, rise slowly from sitting or lying down, and avoid standing for extended periods. If nausea is triggering dehydration, try ginger tea or small sips of water. Rest when needed. Most adjustment symptoms, including dizziness, settle within 2–4 weeks as your body adapts to the medication.
Should I stop taking Mounjaro if I feel dizzy?
Do not stop your medication without speaking to your prescriber first. However, contact your GP or prescriber urgently if dizziness is severe, sudden, or accompanied by chest pain, shortness of breath, or vision changes. For mild dizziness, implement hydration and dietary strategies while your body adjusts — but always report it at your next review.
Is dizziness different between Mounjaro and Wegovy?
Both tirzepatide (Mounjaro) and semaglutide (Wegovy) are GLP-1-based medications and can cause similar adjustment symptoms, including dizziness. However, they work slightly differently — Mounjaro is a dual GIP/GLP-1 agonist, while Wegovy is a GLP-1 agonist only. Individual responses vary considerably. Your prescriber can discuss which medication may suit you best.
How long does dizziness last on Mounjaro?
For most people, dizziness related to Mounjaro improves within 2–4 weeks as your body adjusts to the medication and you establish stable hydration and eating patterns. If dizziness persists beyond 4 weeks, is worsening, or is accompanied by other concerning symptoms, contact your GP for assessment. Tracking your symptoms with our progress tracker can help identify patterns and discuss with your prescriber.
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