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 vs Wegovy in Scotland: Which is Right for You?
Both Mounjaro (tirzepatide) and Wegovy (semaglutide) are prescription-only weight management injections available in Scotland, but they work differently and have distinct clinical profiles. Mounjaro is a dual GIP and GLP-1 receptor agonist, whilst Wegovy activates only the GLP-1 pathway. This guide compares both medications factually, explores trial evidence, and explains how to access each through NHS Scotland or private prescription routes.
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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 and Wegovy Work: Key Mechanism Differences
Mounjaro (tirzepatide) activates two hormone pathways simultaneously: GIP (glucose-dependent insulinotropic polypeptide) and GLP-1 (glucagon-like peptide-1). This dual mechanism may help regulate appetite, reduce food cravings, slow gastric emptying, and support fat utilisation. Wegovy (semaglutide) activates only the GLP-1 pathway, which signals fullness to the brain and slows how quickly food leaves the stomach.
In clinical trials, this difference in mechanism showed measurable differences in weight loss outcomes. The SURMOUNT-1 trial (Mounjaro) showed average weight loss of approximately 15–21% of body weight at the maximum 15 mg dose over 72 weeks. The STEP-1 trial (Wegovy) showed approximately 14.9% average weight loss at the maximum 2.4 mg dose over 68 weeks. Both trials included participants following a reduced-calorie diet and increased physical activity. Individual results vary significantly, and neither medication assures specific outcomes.
Dosing also differs: Mounjaro doses range from 2.5 mg to 15 mg weekly, whilst Wegovy doses range from 0.25 mg to 2.4 mg weekly. Both are once-weekly injections administered via pre-filled pen.
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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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Accessing Mounjaro and Wegovy in Scotland: NHS and Private Routes
NHS Scotland: Both medications are available through NHS specialist weight management services, typically tier 3 services. You'll need a referral from your GP to a specialist weight management clinic. Availability varies by health board, and waiting times can be significant. Ask your GP whether your local health board currently offers these medications and what the referral pathway involves.
Private prescription: Both Mounjaro and Wegovy are available privately through GPhC-registered online prescribing services following an online clinical assessment. A UK-licensed prescriber will review your health and determine suitability. Costs vary by dose and provider. Access is faster than NHS routes but involves out-of-pocket expenses.
Either way, a prescriber must assess your eligibility. You'll generally need a BMI of 30 or above, or 27–29.9 with weight-related health conditions such as type 2 diabetes, high blood pressure, or cardiovascular disease. Use our free BMI calculator above to check your starting point.
Suitability is individual. Some people respond better to one medication than another. Factors like your medical history, other medications, and personal health goals will inform which option is recommended. If you've tried one and it hasn't worked well, a prescriber may suggest switching to the other. A prescriber will also check for contraindications: neither medication is suitable during pregnancy, whilst breastfeeding, or if you have a personal or family history of medullary thyroid cancer or multiple endocrine neoplasia type 2.
Once started, both medications require dose titration (gradual increases) over several weeks to reach an effective maintenance dose. Side effects are common initially—particularly nausea and stomach discomfort—but often improve as your body adjusts. Track your progress with our free progress tracker as you adjust to treatment.
- 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 Mounjaro stronger than Wegovy?
Not exactly. Mounjaro has a dual mechanism (GIP + GLP-1) whilst Wegovy has a single mechanism (GLP-1 only). Clinical trial data shows slightly higher average weight loss with Mounjaro, but individual responses vary considerably. "Stronger" depends on how your body responds. A prescriber will assess which is more suitable for your specific health situation.
Can I switch from Wegovy to Mounjaro in Scotland?
Yes, switching is possible under clinical guidance. If Wegovy hasn't given you the results you hoped for, or you've experienced side effects, a prescriber may recommend trying Mounjaro. Approximate dosing equivalents exist, but any switch must be managed by your healthcare provider. Contact your prescriber or GP to discuss switching options.
How much does Mounjaro cost privately in Scotland?
Private Mounjaro costs vary by dose and provider, ranging roughly £150–£300 per month depending on the dose step. Wegovy typically costs £120–£250 per month. Prices vary between GPhC-registered online pharmacies. Both medications are supplied as 4-week pens (4 weeks of doses), so monthly costs reflect the dose level you're on.
Will NHS Scotland cover Mounjaro or Wegovy?
Both are available on NHS Scotland through specialist weight management services (tier 3). However, availability and prescribing criteria vary by health board. Some areas have quicker access than others. Your GP can advise whether your local health board currently prescribes these medications and what the referral process involves.
What are the main side effects of both medications?
Both commonly cause nausea, diarrhoea, constipation, and stomach discomfort, especially in the first few weeks. Most people find these improve as their body adjusts. Serious side effects are rare but include severe stomach pain (possible pancreatitis), gallbladder problems, and allergic reactions. Always report persistent or severe symptoms to your GP or prescriber immediately.
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