Mounjaro vs Wegovy: Which Weight Loss Injection is Right for You?

Compare Mounjaro and Wegovy head-to-head: efficacy, side effects, cost, and availability in New Zealand to help you...

February 12, 2026

If you're researching weight loss injections in New Zealand, you've likely come across both Mounjaro and Wegovy. Both are highly effective GLP-1 medications, but they work differently and produce different results. This guide compares the two medications head-to-head to help you understand which might be right for you.

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The Key Difference: Single vs Dual Action

The fundamental difference between these medications lies in their mechanism of action:

Wegovy (semaglutide) activates only the GLP-1 receptor
Mounjaro (tirzepatide) activates both the GLP-1 and GIP receptors

This dual-action approach is why Mounjaro consistently outperforms Wegovy in clinical trials. The GIP receptor appears to enhance the effects of GLP-1 activation, creating a synergistic effect on appetite, metabolism, and fat breakdown.

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Weight Loss Results Compared

Clinical trials have directly compared these medications, and the results consistently favour Mounjaro:

Measure	Mounjaro (max dose)	Wegovy (max dose)
Average weight loss	20-22.5%	~15%
Patients losing ≥20%	63%	~32%
Patients losing ≥10%	91%	~75%
Waist circumference reduction	18.4cm	13.0cm

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In the SURMOUNT-5 head-to-head trial, participants on tirzepatide lost an average of 20.2% of their body weight compared to 13.7% for semaglutide over 72 weeks. That's approximately 6.5 percentage points more weight loss with Mounjaro.

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Dosing and Administration

Both medications are administered once weekly via subcutaneous injection using pre-filled pens. However, their dosing schedules differ:

Wegovy Titration (16 weeks)

Weeks 1-4: 0.25mg
Weeks 5-8: 0.5mg
Weeks 9-12: 1.0mg
Weeks 13-16: 1.7mg
Week 17+: 2.4mg (maintenance)

Mounjaro Titration (20 weeks)

Weeks 1-4: 2.5mg
Weeks 5-8: 5mg
Weeks 9-12: 7.5mg
Weeks 13-16: 10mg
Weeks 17-20: 12.5mg
Week 21+: 15mg (maintenance)

Mounjaro has a longer titration period with more dose steps, which may help patients adjust more gradually to the medication.

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Side Effects: Are They Different?

Both medications share similar gastrointestinal side effects, which are the most common complaints:

Nausea
Diarrhoea
Vomiting
Constipation
Abdominal discomfort

Clinical trials show no significant difference in the rate or severity of side effects between the two medications. Both typically cause the most discomfort during dose escalation, with symptoms improving over time.

Both carry the same boxed warning regarding thyroid C-cell tumours and are contraindicated in people with a history of medullary thyroid carcinoma or MEN 2 syndrome.

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Availability in New Zealand

Both medications are available in New Zealand:

Wegovy: Available now. You can start treatment today with a prescription from a registered doctor.
Mounjaro: Approved by Medsafe on 22 December 2025 and now available at pharmacies (at 12 February 2026)

Neither medication is funded by Pharmac for weight loss, so both are private-pay only.

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Cost Comparison

Current and expected pricing in New Zealand:

Medication	Monthly Cost (NZD)	Notes
Wegovy	$460-500	Flat pricing regardless of dose
Mounjaro	$430-875	Varies by dose (2.5mg-15mg)

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Mounjaro's dose-dependent pricing means you'll pay less during the initial titration months. Starting doses (2.5mg at $430, 5mg at $500) are comparable to Wegovy. Higher maintenance doses (10mg at $690, 15mg at $875) cost more than Wegovy's flat rate.

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Which Should You Choose?

Here's our practical guidance:

Consider Wegovy if:

You prefer predictable monthly costs at higher doses
You're achieving good results and don't need to maximise weight loss
You want a simpler dosing schedule

Consider Mounjaro if:

You want to maximise potential weight loss
You haven't achieved your goals with other GLP-1 medications
The higher potential efficacy justifies potentially higher costs at maintenance doses
You prefer the more gradual titration schedule

Switching Between Medications

If you're currently on Wegovy and interested in potentially better results, switching to Mounjaro is now possible. Discuss the timing and transition plan with your prescriber.

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Get Started Today

At Well Revolution, we currently offer comprehensive medical support for Wegovy and Mounjaro treatment in New Zealand. Our chat-based GP service provides: