Wegovy vs Mounjaro in Ireland: Which Weight Loss Injection Is Right for You? (2026)

All medical information is reviewed by our clinical partners at MedicOnline.

Dr. Jahan Khan, CMO @ MedicOnline

IMC 409788

Both Wegovy and Mounjaro are now available in Ireland on private prescription. Both are clinically proven. Both work. So how do you decide which one is right for you? This evidence-based guide cuts through the noise.

If you have been researching weight loss injections in Ireland, you have almost certainly come across these two names. Wegovy (semaglutide) and Mounjaro (tirzepatide) are the two leading prescription GLP-1 medications available to Irish patients in 2026, and the question of which to choose is one of the most common we hear at Bua Health.

The honest answer is that there is no single "better" drug - the right choice depends on your individual health profile, medical history, and what your doctor recommends after assessment. What we can do is lay out exactly what the clinical evidence says, explain how the drugs differ mechanically, and help you understand who each one tends to suit best.

How Each Drug Works

Understanding the difference in mechanism is key to understanding why the two drugs perform differently in clinical trials.

Wegovy (semaglutide) is a GLP-1 receptor agonist. It mimics glucagon-like peptide-1, a naturally occurring gut hormone that signals fullness to the brain, slows gastric emptying, and reduces appetite.

Mounjaro (tirzepatide) is a dual GIP/GLP-1 receptor agonist. It activates both receptor pathways simultaneously. GIP receptor distribution differs from GLP-1, and combined activation appears to produce a greater average metabolic effect in direct trials.

In practical terms, both medications are effective - but tirzepatide currently shows greater average weight loss at standard maximum doses in direct comparison trials.

What the Clinical Trials Tell Us

The most important direct comparison is the SURMOUNT-5 trial (NEJM 2025), which compared tirzepatide and semaglutide head-to-head in adults with obesity (without type 2 diabetes).

Over 72 weeks, mean body weight reduction was 20.2% with tirzepatide versus 13.7% with semaglutide (p<0.001). Higher thresholds were also reached more often with tirzepatide (20% and 25% categories), and waist reduction was greater (-18.4 cm vs -13.0 cm).

It is also important context that higher-dose Wegovy (7.2 mg) has reported stronger outcomes in newer STEP UP data (PubMed: 40353578), which may narrow this gap once approved by EMA for EU markets.

Side Effects: How Do They Compare?

Both medications share broadly similar side effect profiles, consistent with the GLP-1 class. Most common effects are gastrointestinal - nausea, constipation, diarrhoea, and stomach discomfort - particularly during dose escalation.

In SURMOUNT-5, GI adverse events leading to treatment discontinuation were 5.6% for semaglutide vs 2.7% for tirzepatide, suggesting a possible tolerability advantage for tirzepatide in that trial context.

Both drugs are contraindicated in patients with personal or family history of medullary thyroid carcinoma (MTC) or MEN 2, and neither should be used during pregnancy.

Wegovy vs Mounjaro: Side by Side

Access and Cost in Ireland in 2026

Both Wegovy and Mounjaro are available in Ireland on private prescription. Neither is currently covered by the HSE or the Drugs Payment Scheme for weight management, though reimbursement assessments are ongoing via NCPE.

Wegovy became formally available in Ireland in March 2025. Mounjaro is also available via private prescription from licensed Irish doctors for clinically eligible patients.

Following Eli Lilly's September 2025 price increase for Mounjaro, Wegovy is generally the more affordable option at standard maintenance doses. Prices vary by provider and dose level, so compare full costs including consultation fees.

Who Might Be Better Suited to Each?

This is ultimately a clinical decision for you and your doctor, but trial and real-world data suggest practical patterns:

• Wegovy may suit better if cardiovascular disease is a key concern as semaglutide has a proven and licensed cardiovascular risk-reduction indication.
• Mounjaro may suit better if maximum average weight loss is your primary objective and you do not have established cardiovascular disease.

Individual response still varies considerably. Some patients do better on semaglutide than tirzepatide despite trial averages. The right approach is to start, monitor, and adjust under medical supervision.

Ready to get started with Bua?

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Sources and References

• 1. Aronne LJ, et al. NEJM 2025. SURMOUNT-5 publication
• 2. Mamas A, et al. EHJ Open 2025. EHJ Open publication
• 3. STEP UP trial reference: pubmed 40353578
• 4. SELECT trial: Semaglutide and Cardiovascular Outcomes in Obesity without Diabetes
• 5. EMA SmPC pages for Wegovy and Mounjaro.

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