Switching from Ozempic 1 mg to Mounjaro: Equivalent Dosing
Start with Mounjaro 5 mg once weekly when transitioning from Ozempic 1 mg, then titrate upward based on tolerability and treatment goals. 1
Why There Is No Direct "Equivalent" Dose
Tirzepatide (Mounjaro) and semaglutide (Ozempic) are fundamentally different medications - tirzepatide is a dual GIP/GLP-1 receptor agonist while semaglutide is a selective GLP-1 receptor agonist only. 1
The dual mechanism means you cannot simply convert doses based on GLP-1 activity alone - the addition of GIP receptor agonism creates different pharmacodynamics that make direct dose equivalency impossible. 1
Recommended Transition Strategy
Initial dosing:
- Begin with Mounjaro 2.5 mg once weekly for 4 weeks (starting dose per FDA labeling). 2
- Increase to 5 mg once weekly after the initial 4-week period. 2
Subsequent titration:
- Increase by 2.5 mg increments every 4 weeks as tolerated, up to a maximum of 15 mg once weekly. 2
- The maintenance doses are 5 mg, 10 mg, or 15 mg once weekly depending on glycemic control and weight management goals. 2
Why Start Low Despite Prior GLP-1 RA Exposure
Even though your patient has developed tolerance to semaglutide's GI effects, tirzepatide's dual mechanism may cause new or different gastrointestinal side effects. 1
Gradual dose titration is essential to minimize gastrointestinal adverse effects (nausea, vomiting, diarrhea, esophageal reflux), which remain common with tirzepatide despite prior GLP-1 RA use. 3, 1
Tirzepatide may delay gastric emptying differently than semaglutide, potentially affecting oral medication absorption. 1
Expected Efficacy Comparison
If targeting glycemic control:
- Tirzepatide 10 mg and 15 mg demonstrate superior HbA1c reduction compared to semaglutide 1 mg (additional 0.39-0.45 percentage point reduction). 4
- Tirzepatide 5 mg shows comparable HbA1c reduction to semaglutide 1 mg. 4
If targeting weight loss:
- Tirzepatide produces significantly greater weight reduction than semaglutide 1 mg across all doses: 5 mg (-1.9 kg more), 10 mg (-3.6 kg more), and 15 mg (-5.5 kg more). 4
- For weight management specifically, tirzepatide 15 mg achieved 14.7% weight loss compared to 9.6% with semaglutide in head-to-head trials. 1
Critical Safety Monitoring During Transition
Assess efficacy and safety at least monthly for the first 3 months, then at least quarterly thereafter. 1
Monitor for gastrointestinal disorders including severe constipation and small-bowel obstruction/ileus. 1
Be alert for cholelithiasis and gallstone-related complications. 1
Use caution in patients with kidney disease when initiating or increasing dose due to potential risk of acute kidney injury. 1
Contraindications to Verify Before Switching
Do not use in patients with personal or family history of medullary thyroid cancer or multiple endocrine neoplasia type 2 (both medications carry this black box warning). 1
Both medications are contraindicated in these populations, so if your patient is currently on Ozempic, this should already be confirmed. 1
Practical Timing Consideration
- You can start Mounjaro at the time of the next scheduled Ozempic dose - no washout period is required given the once-weekly dosing schedule of both medications. 3