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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Can You Take Sertraline With Mounjaro?
Sertraline and Mounjaro can generally be taken together, but it's important to understand how they interact and whether this combination is right for you. Sertraline is an SSRI antidepressant commonly prescribed in the UK, while Mounjaro (tirzepatide) is a prescription-only weight management injection licensed by the MHRA. Both medications affect how your body processes food and mood, so your GP or prescriber needs to know if you're taking both. This guide explains what you need to know about combining these medications safely.
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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 Sertraline and Mounjaro Work Together
Sertraline is a selective serotonin reuptake inhibitor (SSRI) that increases serotonin availability in the brain to help manage depression, anxiety, and related conditions. Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist that works on appetite regulation and gastric emptying in the gut.
The two medications work through different mechanisms — sertraline affects brain chemistry, while Mounjaro affects appetite and metabolic hormones. There is no known direct pharmacological interaction between them. However, both can affect appetite and eating behaviour in different ways: sertraline may change appetite as a side effect, and Mounjaro specifically works by reducing appetite. This combined effect is usually manageable but worth discussing with your prescriber.
- Sertraline can cause nausea, which may be compounded by Mounjaro's GI side effects
- Both medications may affect weight differently in different people
- Your prescriber needs to assess your individual circumstances
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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.
Important Considerations Before Starting Mounjaro
If you're taking sertraline and considering Mounjaro, inform your GP or prescriber at your clinical assessment. They will review your full medication list and medical history to determine whether this combination is appropriate for you. Key factors include how well your sertraline is working, any current side effects, your BMI eligibility, and your overall health status.
You can use our free BMI calculator above to check your weight against NHS eligibility thresholds — adults with a BMI of 30 or above, or 27 or above with weight-related health conditions, may be eligible for Mounjaro. Your prescriber will conduct a full assessment and may monitor you more closely if you're on sertraline, particularly during the initial weeks of Mounjaro treatment.
- Always disclose all medications, including sertraline, before Mounjaro prescription
- Report any unusual changes in mood, appetite, or side effects to your GP
- Sertraline dose should not be stopped or changed without medical guidance
- 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 it safe to take sertraline and Mounjaro together?
Generally, yes — there is no known direct pharmacological interaction between sertraline and Mounjaro. However, both medications can affect appetite and cause nausea, so your prescriber needs to assess your individual circumstances. Always disclose sertraline use during your Mounjaro clinical assessment.
Will Mounjaro affect how sertraline works?
Mounjaro is unlikely to directly interfere with sertraline's effectiveness. However, changes in appetite and eating patterns caused by Mounjaro may indirectly affect how you feel overall. Some people find their mood stabilises further with weight loss, while others may need closer monitoring. Your GP can advise.
Can sertraline affect Mounjaro's weight loss effectiveness?
Sertraline itself doesn't reduce Mounjaro's effectiveness, but SSRIs can sometimes affect weight differently in different people. Some gain weight, some lose weight, and some see no change. Mounjaro works alongside your current medication, and your prescriber will consider this during assessment.
What should I tell my prescriber about sertraline?
Tell your prescriber the name of your SSRI (sertraline), the dose you're taking, how long you've been on it, and how well it's working for you. Also mention any side effects you experience. This helps them assess whether Mounjaro is suitable and whether any dose adjustments or monitoring are needed.
Can I stop sertraline to start Mounjaro?
No — you should never stop sertraline without medical guidance from your GP. Stopping SSRIs suddenly can cause withdrawal symptoms and mood problems. If your GP thinks sertraline should be stopped, they will supervise a gradual reduction. Mounjaro can be started while you're on sertraline.
Ready to take control of your weight loss journey?
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