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
Can You Smoke While On Mounjaro?
Yes, you can smoke while taking Mounjaro (tirzepatide), as there is no direct pharmacological interaction between smoking and the medication itself. However, smoking significantly increases your risk of the serious health conditions that Mounjaro is prescribed to help manage — including heart disease, stroke, and type 2 diabetes. If you're eligible for Mounjaro treatment in the UK, your prescriber will assess your overall health during your clinical consultation and may discuss smoking cessation as part of your weight management plan. Mounjaro is available through NHS specialist services or private prescription following an online consultation.
10,000+ calculations today · NHS-aligned thresholds · 100% free
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.
Smoking and Mounjaro — What the Evidence Shows
There is no direct chemical interaction between smoking and tirzepatide — smoking does not prevent Mounjaro from working or reduce its effectiveness. However, smoking and excess weight together create a significant health risk. Smoking increases your risk of type 2 diabetes, cardiovascular disease, and stroke — the very conditions Mounjaro may help you manage. If you're taking Mounjaro as part of a weight management programme, quitting smoking would amplify the health benefits you're trying to achieve. Your prescriber may ask about your smoking status during your clinical assessment, as this informs your overall health profile. Mounjaro KwikPen injections are self-administered once weekly, and smoking does not affect how you use the injection or how your body processes the medication. The focus should be on supporting your overall cardiovascular and metabolic health alongside weight management.
Clinically BackedWeight Loss
No appointments. No waiting rooms. Just care — from a UK-regulated online pharmacy.
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.
Accessing Mounjaro in the UK — Cost and Options
In the UK, Mounjaro is available through two main routes. NHS access is through specialist tier 3 weight management services, typically requiring a GP referral — availability and waiting times vary significantly by region. Private prescription access is through online consultations with UK-licensed prescribers, followed by dispensing through a GPhC-registered pharmacy. Private Mounjaro costs range from approximately £130–£320 monthly depending on your dose. Doses start at 2.5 mg weekly and increase gradually up to 15 mg. Your prescriber will assess your Mounjaro eligibility UK based on your BMI, health conditions, and medical history. Use our free BMI calculator above to check where you currently fall and whether you may meet initial eligibility criteria before seeking a consultation.
- 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.
Does smoking affect how Mounjaro works?
No, smoking does not interact with tirzepatide or reduce its effectiveness. However, smoking increases your cardiovascular and diabetes risk, which are conditions Mounjaro is prescribed to help manage. Quitting smoking would complement your weight management efforts and improve your overall health outcomes significantly.
Will my prescriber ask about smoking?
Yes. During your online clinical assessment, your prescriber will ask about your smoking status as part of your overall health evaluation. This helps them assess your suitability for Mounjaro and understand your total health risk profile. They may discuss smoking cessation as part of your weight management plan.
What's the difference between Mounjaro and Wegovy?
Both are prescription-only once-weekly injections for weight management in the UK. Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist with a maximum dose of 15 mg. Wegovy (semaglutide) is a GLP-1 agonist only with a maximum dose of 2.4 mg. Clinical trials showed Mounjaro produced slightly higher average weight loss, though individual results vary significantly.
How much does Mounjaro cost privately in the UK?
Private Mounjaro costs typically range from £130–£320 per month depending on your dose and provider. Pricing is based on the tirzepatide dose you're prescribed (starting at 2.5 mg and titrating up weekly). NHS access is available through specialist services but involves referral and varies by region. Our GLP-1 weight loss calculator can help you estimate potential outcomes at different doses.
How do I get a Mounjaro prescription in the UK?
You can access Mounjaro through NHS specialist weight management services (via GP referral) or privately through an online consultation with a UK-licensed prescriber. For private access, you'll have a virtual consultation assessing your health, BMI, and eligibility. If approved, a prescription is issued and dispensed by a GPhC-registered pharmacy. NHS access typically involves a longer pathway and varies by region.
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.