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 Runny Nose a Side Effect of Mounjaro?
Runny nose is not officially listed as a common side effect of Mounjaro (tirzepatide) in UK clinical trial data or the product information. However, some people taking Mounjaro report nasal congestion or rhinitis-like symptoms. This guide explains what the evidence shows, why it might occur, and when to speak to your GP. Mounjaro is a prescription-only GLP-1 receptor agonist used for weight management in UK adults with eligible BMI and health conditions. If you're experiencing persistent nasal symptoms while taking Mounjaro, it's important to understand whether they're related to the medication or another cause.
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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.
What Does the Clinical Evidence Show?
In the SURMOUNT clinical trials that led to Mounjaro's UK approval, nasal congestion or runny nose was not reported as a common side effect. The most frequently reported side effects were gastrointestinal: nausea, diarrhoea, vomiting, and constipation. However, post-marketing reports and patient forums suggest some individuals do experience nasal symptoms while taking tirzepatide.
These symptoms are not well understood but may occur through indirect mechanisms rather than direct GLP-1 receptor action. Possible explanations include:
- Fluid and electrolyte shifts caused by the medication
- Immune response modulation from GLP-1 signalling
- Secondary effects from nausea or gastrointestinal changes
- Coincidental viral infection or seasonal allergies unrelated to Mounjaro
Because runny nose is not a formally documented side effect, it's classified as uncommon or rare, meaning it affects fewer than 1 in 100 people taking the medication. This is very different from common side effects like nausea, which affect more than 1 in 10 people.
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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 Contact Your GP
If you develop a runny nose or nasal congestion while taking Mounjaro, contact your GP if:
- Symptoms are severe, persistent, or worsening over several weeks
- You also have fever, facial pain, or signs of sinus infection
- Symptoms interfere with your daily activities or sleep
- You're unsure whether symptoms are related to Mounjaro or another cause
- You have a history of allergies or hay fever and symptoms feel different from usual
Your GP can assess whether your symptoms are medication-related or due to infection, allergy, or environmental factors. Do not stop taking Mounjaro without medical guidance. If you need to discuss side effects, your prescriber can help determine whether continuing at your current dose is appropriate or whether adjusting your dose titration schedule would help.
- 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 runny nose listed as a common side effect of Mounjaro in the UK?
No. Runny nose is not listed as a common or very common side effect in UK clinical trial data. The most common side effects are nausea, diarrhoea, vomiting, and constipation. Nasal symptoms may occur rarely in some individuals but are not a formally documented effect of tirzepatide.
Could a runny nose be caused by something other than Mounjaro?
Yes, very likely. Runny nose has many causes including viral infections, seasonal allergies, hay fever, sinus issues, and environmental factors. It may be coincidental timing rather than a Mounjaro side effect. Your GP can help identify the actual cause.
How does Mounjaro differ from Wegovy in terms of side effects?
Mounjaro is a dual GIP and GLP-1 receptor agonist, while Wegovy contains semaglutide, a GLP-1 agonist only. Both share similar gastrointestinal side effects. Mounjaro may have a slightly different side effect profile due to its dual mechanism, but nasal congestion is not a documented effect for either medication.
Should I stop taking Mounjaro if I develop a runny nose?
Do not stop Mounjaro without speaking to your GP or prescriber first. If nasal symptoms are mild and you suspect they're unrelated to the medication, continue as normal. If symptoms are severe or concerning, contact your healthcare provider for guidance.
Is there a link between GLP-1 medications and rhinitis or sinus problems?
There is no established clinical evidence linking GLP-1 receptor agonists like Mounjaro or Wegovy to rhinitis or chronic sinus problems. If nasal symptoms persist, your GP may recommend investigation to rule out infection, allergy, or other causes unrelated to the medication.
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