Ozempic vs Mounjaro: complete comparison for weight loss

Why compare Ozempic and Mounjaro?

Ozempic (semaglutide) and Mounjaro (tirzepatide) represent the new generation of medical treatments for obesity and type 2 diabetes. Although both belong to the incretin-based medication family, they have important differences.

Many patients ask: which is better for me? The answer depends on multiple factors such as the primary goal, existing medical conditions and availability.

At Clínica Eupnea in Palamós, our endocrinology team conducts a comprehensive evaluation to recommend the most appropriate treatment.

Differences in mechanism of action

Ozempic (semaglutide) — GLP-1 agonist: Acts exclusively on the GLP-1 receptor. Reduces appetite, slows gastric emptying, stimulates glucose-dependent insulin secretion.

Mounjaro (tirzepatide) — Dual GIP/GLP-1 agonist: Acts on two receptors: GIP and GLP-1. All effects of semaglutide, plus improved adipose tissue sensitivity via GIP and possible effects on body fat distribution.

Efficacy comparison in weight loss

Ozempic (STEP trials): Average loss of 15-17% over 68 weeks. ~70% lose ≥10%, ~30-35% lose ≥20%.

Mounjaro (SURMOUNT trials): Average loss of 22.5% over 72 weeks. ~90% lose ≥10%, ~57% lose ≥20%.

SURMOUNT-5 directly compared both: tirzepatide 20.2% vs semaglutide 13.7% over 72 weeks.

Conclusion: Mounjaro consistently outperforms Ozempic in weight loss, although both achieve clinically significant results.

Diabetes control: head to head

HbA1c reduction: Ozempic ~1.5-1.8% | Mounjaro ~2.0-2.1%

Patients achieving HbA1c <7%: Ozempic ~70-80% | Mounjaro ~85-97%

Cardiovascular data: Ozempic has an advantage: the SELECT study demonstrated a 20% reduction in major cardiovascular events. Mounjaro does not yet have completed cardiovascular outcome studies.

For patients with high cardiovascular risk, Ozempic may be the preferred option until tirzepatide cardiovascular data are available.

Side effects: which is more tolerable?

The profiles are remarkably similar:

• Nausea: Ozempic ~20%, Mounjaro ~18-25%
• Diarrhoea: Ozempic ~10%, Mounjaro ~12-17%
• Vomiting: Ozempic ~8%, Mounjaro ~7-12%

Discontinuation rates: Ozempic ~5-7%, Mounjaro ~5-8%. Both are well tolerated with gradual dose escalation.

Administration and dosing

Ozempic: Weekly injection. Doses: 0.25→0.5→1→2 mg (diabetes), up to 2.4 mg (obesity/Wegovy).

Mounjaro: Weekly injection. Doses: 2.5→5→7.5→10→12.5→15 mg. Escalation every 4 weeks.

Both are injected in the abdomen, thigh or arm using easy-to-use pre-filled pens.

Cost and accessibility in Spain

Ozempic: Available and funded for type 2 diabetes. Wegovy (obesity): not funded by the NHS. Cost: ~€140-300/month.

Mounjaro: Available for type 2 diabetes. Zepbound (obesity): pending EU approval.

Contact Clínica Eupnea for updated information on availability and options.

How to choose between Ozempic and Mounjaro

Ozempic may be preferable if: High cardiovascular risk, good previous response to semaglutide, preference for a medication with more clinical experience.

Mounjaro may be preferable if: Maximum weight loss is the primary goal, insufficient response to semaglutide, diabetes with poor glycaemic control.

The final decision should be made by your endocrinologist considering your complete medical history.

Frequently asked questions