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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Mounjaro Headaches: Understanding UK Costs & Access
Headaches are a common side effect experienced by some people taking Mounjaro (tirzepatide), affecting up to 1 in 10 users. This guide explains where to access Mounjaro in the UK, what it costs at different doses, and how NHS and private routes compare. If you're experiencing headaches during your Mounjaro treatment, understanding your access options and costs can help you manage your care effectively. We'll cover private prescription costs by KwikPen dose and explain the difference between NHS specialist services and private online prescribing 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.
Private Mounjaro Costs by Dose in the UK
Private prescription costs for Mounjaro vary by dose and provider, but expect these approximate ranges:
- 2.5 mg (starting/adjustment dose): £129–£180 per KwikPen (4-week supply)
- 5 mg (first maintenance): £149–£200 per KwikPen
- 10 mg (escalation): £180–£240 per KwikPen
- 15 mg (maximum dose): £200–£320 per KwikPen
Each KwikPen contains 4 weekly injections. Annual costs range from approximately £2,700–£4,800 depending on your dose and which private provider or online pharmacy you use. Costs vary because different GPhC-registered pharmacies set their own prices. Many private providers offer subscription models with slight discounts if you order regularly. If you experience headaches at a particular dose, your prescriber may adjust your dose during titration, which affects ongoing costs.
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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.
NHS vs Private Access: Routes & What to Expect
NHS access requires referral to a tier 3 specialist weight management service through your GP. Mounjaro is now approved by NICE for NHS use, but availability varies significantly by region. Waiting lists in many areas are several months. Once approved, NHS treatment is free. Private access requires an online consultation with a UK-licensed prescriber. After assessment, a prescription is issued if clinically appropriate and dispensed by a GPhC-registered pharmacy. Private access is faster (often within days) but costs apply. Both routes require individual clinical assessment and consideration of your mounjaro uk prescription eligibility based on BMI and health conditions. If headaches become problematic, you can discuss dose adjustment or alternative options like Wegovy (semaglutide) with your prescriber in either route.
- 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 headaches a serious side effect of Mounjaro?
Headaches are reported as common (affecting up to 1 in 10 people) but not usually serious. Most headaches are mild to moderate and often improve as your body adjusts to the medication. However, if you experience severe, persistent, or worsening headaches—especially sudden severe headache—contact your GP or NHS 111 immediately, as this could indicate something more serious requiring medical attention.
How much does Mounjaro cost privately at the 5mg dose?
Private Mounjaro 5 mg typically costs £149–£200 per KwikPen (4-week supply) in the UK. Prices vary between GPhC-registered online pharmacies. Some providers offer discounts for regular subscriptions. Always compare providers and check they are GPhC-registered before ordering. Total annual cost at this dose is approximately £2,800–£3,200.
How long is the wait for Mounjaro on the NHS?
NHS waiting times vary significantly by region and ICB. Some areas have waiting lists of 3–6 months, whilst others may be longer due to high demand. Access is through tier 3 specialist weight management services after GP referral. Private routes typically offer prescriptions within days of online assessment, making them faster but at a cost.
Can I switch from Mounjaro to Wegovy if I get headaches?
Yes, if headaches are problematic, your prescriber may suggest dose adjustment, waiting for your body to adapt, or switching to an alternative like Wegovy (semaglutide). Wegovy users report headaches less frequently than Mounjaro users, though they can still occur. Any medication change must be discussed with your prescriber and managed properly.
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.