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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Does Mounjaro Cause Night Sweats?
Night sweats are not listed as a common side effect of Mounjaro in UK clinical data, but some people do report experiencing them while taking tirzepatide. Night sweats may occasionally occur as part of the body's adjustment to this dual GIP and GLP-1 receptor agonist medication, or they may be related to other factors such as diet changes, increased physical activity, or underlying health conditions. If you're experiencing night sweats after starting Mounjaro, it's important to understand what might be causing them and when to contact your GP for advice.
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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 Works and Why Side Effects Occur
Mounjaro (tirzepatide) is a once-weekly prescription injection that activates both GIP and GLP-1 hormone pathways in the body. These pathways help regulate appetite, blood sugar control, and how your body processes food. As your body adjusts to these hormonal changes during Mounjaro dose titration—starting at 2.5 mg and gradually increasing to your maintenance dose—you may experience temporary side effects.
Night sweats during the adjustment period could be related to:
- Metabolic changes as your body responds to the medication
- Reduced calorie intake affecting body temperature regulation
- Increased physical activity alongside the medication
- Individual variation in how your body adapts to hormonal signalling
Most side effects of Mounjaro typically improve after the first few weeks as your body adjusts. Unlike common side effects such as nausea and diarrhoea, night sweats are not specifically documented in the UK prescribing information, which suggests they are rare or not directly caused by the medication itself.
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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 Night Sweats
If you're experiencing night sweats while taking Mounjaro on an NHS NICE-approved weight management programme or through private prescription, contact your GP if:
- Night sweats are severe, persistent, or worsening over weeks
- They're affecting your sleep quality and daily functioning
- They occur alongside fever, unintentional weight loss, or other symptoms
- You're unsure whether they're related to Mounjaro or another cause
Your GP can assess whether the night sweats are a temporary adjustment response or a sign of another underlying condition. They may recommend dose adjustment, timing changes (such as injecting at a different time of day), or other management strategies. Always inform your prescriber of any new or concerning symptoms—this is important information for your ongoing care with Mounjaro.
- 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.
Are night sweats a known side effect of Mounjaro?
Night sweats are not listed as a common or very common side effect of Mounjaro in UK clinical data. Most documented side effects are gastrointestinal (nausea, diarrhoea, constipation). However, individual responses vary, and some people may experience night sweats during the adjustment period or as part of metabolic changes.
How does Mounjaro compare to Wegovy for causing night sweats?
Both Mounjaro and Wegovy are GLP-1-based medications (Mounjaro also includes GIP activation). Night sweats are not commonly reported with either medication in clinical trials. Individual experiences differ, and any new symptoms should be discussed with your GP.
Could night sweats be from diet changes rather than Mounjaro?
Yes, absolutely. Reduced calorie intake, changes in meal timing, and dietary shifts can independently cause night sweats or temperature regulation changes. Your body's metabolic adjustment to weight loss—regardless of medication—may contribute to this symptom.
Should I stop taking Mounjaro if I have night sweats?
No—do not stop Mounjaro without medical guidance. Contact your GP or prescriber to discuss the symptoms. They can assess the cause, determine if it's a temporary adjustment response, and advise on next steps. Stopping suddenly is not recommended without professional guidance.
How long do side effects of Mounjaro typically last?
Most common side effects (nausea, diarrhoea, constipation) tend to improve within 2–4 weeks as your body adjusts. If night sweats persist beyond this adjustment period or worsen, discuss them with your GP to rule out other causes.
Ready to take control of your weight loss journey?
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