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
Is Dizziness a Side Effect of Mounjaro?
Dizziness can occur with Mounjaro (tirzepatide), though it is not listed as a very common side effect. If you experience dizzy spells while taking this prescription weight management injection, it may be related to several factors including dehydration, low blood sugar, rapid dose changes, or medication interactions. This guide explains what the evidence shows, when to seek help, and practical steps to manage symptoms whilst using Mounjaro in the UK.
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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.
How Mounjaro May Cause Dizziness
Dizziness with Mounjaro can happen through several mechanisms. Dehydration is common because Mounjaro often causes nausea, vomiting, and diarrhoea — fluid loss can lead to dizziness and lightheadedness. Low blood sugar (hypoglycaemia) is another risk, especially if you are taking diabetes medications alongside tirzepatide, as the combination may lower glucose more than expected. Rapid dose titration — increasing from 2.5 mg to 5 mg to 10 mg — can also trigger dizziness as your body adjusts to the dual GIP and GLP-1 receptor activation. Medication interactions with oral contraceptives, diabetes drugs, or blood pressure medications can amplify dizziness risk. Additionally, Mounjaro slows gastric emptying, which may affect nutrient absorption and energy levels, contributing to lightheadedness.
- Stay hydrated — drink water consistently throughout the day
- Eat regular, balanced meals to stabilise blood sugar
- Rise slowly from lying or sitting to avoid postural dizziness
- Monitor blood sugar if diabetic
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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
Most mild dizziness settles within the first few weeks as your body adjusts to Mounjaro. However, contact your GP if dizziness is severe, persistent, or worsening, or if you experience additional symptoms such as chest pain, shortness of breath, confusion, or blurred vision. These may indicate a more serious condition unrelated to Mounjaro — for example, pancreatitis or gallbladder issues, which require urgent assessment. If dizziness occurs immediately after a dose increase and is accompanied by severe nausea or vomiting, inform your prescriber before your next injection. Your GP can check your blood pressure, blood sugar levels, and medication interactions. Do not stop Mounjaro without medical guidance.
- 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 of Mounjaro in clinical trials, but it can occur. It is more likely related to dehydration, blood sugar changes, or dose adjustments than to tirzepatide directly. If dizziness persists beyond the first few weeks, discuss it with your prescriber.
Can Mounjaro cause dizziness if I am diabetic?
Yes, there is increased risk if you take insulin or sulphonylureas alongside Mounjaro. The combination may lower blood sugar more than expected. Your prescriber may adjust diabetes medication doses. Monitor your blood sugar regularly and report dizziness to your GP.
What should I do if I feel dizzy after taking Mounjaro?
Sit or lie down immediately. Drink water slowly. Avoid driving or operating machinery. If dizziness is severe or accompanied by chest pain, shortness of breath, or confusion, seek urgent medical help. For mild dizziness, rest and stay hydrated — it often improves within a few hours.
Does dizziness mean Mounjaro is not right for me?
Not necessarily. Mild dizziness during the first few weeks is often temporary. However, if it is severe or persistent, your prescriber may adjust your dose, slow the titration schedule, or recommend a different medication. Always discuss ongoing symptoms with your GP before stopping treatment.
How is Mounjaro different from Wegovy if both can cause dizziness?
Both Mounjaro (tirzepatide, a dual GIP/GLP-1 agonist) and Wegovy (semaglutide, a GLP-1 agonist) can cause dizziness through similar mechanisms: dehydration, blood sugar changes, and dose adjustment. Mounjaro has a different starting dose and titration schedule, which may affect side effect timing. Your prescriber will assess which is more suitable for you based on your individual health profile and medical history.
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.