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Research10 min readFebruary 12, 2025
Mounjaro vs Qsymia for Weight Loss
A detailed comparison of Mounjaro and Qsymia. Which weight loss medication is more effective and which has fewer side effects?
By Med Consumer Watch Team
Mounjaro (tirzepatide) and Qsymia (phentermine/topiramate) both help with weight loss, but they're very different medications. Here's how they compare.
Weight Loss Results
Head-to-head comparison:
• Mounjaro: 20-26% average weight loss at maximum dose
• Qsymia: 7-10% average weight loss at maximum dose
Mounjaro produces significantly more weight loss in clinical trials.
How They Work
Different mechanisms:
- Mounjaro - GLP-1/GIP dual agonist; mimics satiety hormones; slows digestion; improves insulin sensitivity
- Qsymia - Stimulant (phentermine) plus anticonvulsant (topiramate); suppresses appetite through different pathways
Side Effects
Mounjaro side effects:
• Nausea, vomiting, diarrhea
• Constipation
• Injection site reactions
• Fatigue
Qsymia side effects:
• Tingling (paresthesia)
• Cognitive effects ("brain fog")
• Dry mouth
• Constipation
• Insomnia, anxiety
Both medications have serious contraindications. Qsymia carries significant birth defect risks; Mounjaro has thyroid tumor warnings.
Administration
How you take them:
• Mounjaro: Weekly injection
• Qsymia: Daily oral pill
Some prefer pills; others don't mind weekly injections.
Cost
Typical costs:
• Mounjaro: $1,000+/month without insurance
• Qsymia: $200-300/month
Qsymia is significantly cheaper, but produces less weight loss.
The Bottom Line
Mounjaro is more effective for weight loss but more expensive and requires injections. Qsymia is less effective but cheaper and oral. For maximum weight loss, Mounjaro wins. For those who can't access or afford GLP-1s, or who can't tolerate injections, Qsymia remains a viable option.
Sources & References
- FDA - Mounjaro and Qsymia Prescribing Information
Medical Disclaimer
This article is for informational purposes only and is not intended as medical advice. Always consult with a qualified healthcare provider before making decisions about your health or medications. Individual experiences may vary.