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
Low Blood Pressure on Mounjaro: What You Need to Know
Low blood pressure (hypotension) is not listed as a common side effect of Mounjaro (tirzepatide) in UK clinical data, but some people may experience dizziness, lightheadedness, or fatigue whilst taking the medication — symptoms that can be associated with blood pressure changes. If you're already taking blood pressure medication or have a history of low blood pressure, it's important to understand how Mounjaro may affect you. Always speak to your GP or prescriber if you experience persistent dizziness or unusual symptoms whilst on this medication.
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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.
How Mounjaro Affects Blood Pressure
Mounjaro (tirzepatide) works as a dual GIP and GLP-1 receptor agonist, activating two natural hormone pathways to help regulate appetite and blood sugar. In clinical trials like SURMOUNT-1, the primary focus was weight loss rather than blood pressure monitoring, though some participants experienced modest improvements in cardiovascular markers. The mechanism of action does not directly lower blood pressure, but weight loss itself — which Mounjaro may support — can lead to reduced blood pressure over time. However, if you're already taking antihypertensive medications (blood pressure tablets), the combination of weight loss plus existing medication could theoretically lower your blood pressure further. This is why ongoing monitoring by your GP or prescriber is essential. Some people report dizziness or lightheadedness when starting Mounjaro, which may reflect blood pressure fluctuations as your body adjusts, dehydration, or the side effects of nausea and appetite suppression.
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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.
What to Do If You Experience Low Blood Pressure Symptoms
If you develop persistent dizziness, fainting, blurred vision, confusion, or extreme fatigue whilst taking Mounjaro, contact your GP or prescriber immediately — these can be signs of problematic low blood pressure. In the meantime, simple measures like staying well-hydrated, eating regularly despite reduced appetite, and rising slowly from sitting or lying down may help. If you take blood pressure medication, your prescriber may need to adjust your doses as you lose weight on Mounjaro. Use our free GLP-1 weight loss calculator to track your expected progress, and keep your GP informed of any symptoms. Never stop taking blood pressure medication without your GP's guidance, even if you feel your pressure might be dropping — sudden changes can be dangerous.
- 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.
Can Mounjaro directly cause low blood pressure?
Low blood pressure is not a common or expected side effect of Mounjaro itself. However, dizziness and fatigue — which some people report — can be associated with blood pressure changes. Weight loss from Mounjaro, combined with existing blood pressure medication, may lower your pressure further, so GP monitoring is essential.
Should I stop my blood pressure medication if I'm taking Mounjaro?
No — never stop blood pressure medication without your GP's advice. As you lose weight on Mounjaro, your prescriber may need to adjust your doses to prevent blood pressure becoming too low. Regular monitoring is key.
What symptoms of low blood pressure should I watch for?
Watch for dizziness, lightheadedness, blurred vision, fainting, confusion, or extreme fatigue. If you experience these persistently or severely, contact your GP immediately. Mild dizziness when starting Mounjaro may settle as your body adjusts.
Is Mounjaro safe if I have a history of low blood pressure?
You should inform your prescriber if you have a history of low blood pressure before starting Mounjaro. They can assess your suitability, monitor you closely, and adjust any existing medications as needed. UK prescribers will take this into account during clinical assessment.
How can I minimise dizziness whilst taking Mounjaro?
Stay well-hydrated, eat small regular meals even if appetite is reduced, rise slowly from sitting or lying, and avoid rapid movements. These practical steps may help reduce dizziness. If symptoms persist, speak to your GP — they may adjust your dose or medications.
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.