What tirzepatide is
Tirzepatide is the first approved medication that activates two hormone receptors: GIP (glucose-dependent insulinotropic polypeptide) and GLP-1. It's taken as a single injection once a week.
How it works
GLP-1 reduces appetite, slows digestion, and helps release insulin. GIP adds to the insulin response and appears to improve how the body handles fat and sugar. Acting on both pathways produced larger average weight loss in trials than GLP-1 alone.
A short history
Tirzepatide was approved for type 2 diabetes in 2022 (as Mounjaro) and for chronic weight management in 2023 (as Zepbound). In 2024, the FDA also approved it for moderate to severe obstructive sleep apnea in adults with obesity.
What the research shows
- Weight loss: in SURMOUNT-1, adults on the 15 mg dose lost an average of 20.9% of their body weight over 72 weeks, compared with 3.1% on placebo.
- Head to head: in SURMOUNT-5, tirzepatide led to an average loss of 20.2% compared with 13.7% for semaglutide over 72 weeks.
- After stopping: in SURMOUNT-4, people who switched to placebo regained much of their lost weight, while those who continued kept losing. Like semaglutide, it works best long term.
What to expect
- Weeks 1 to 4: the 2.5 mg starting dose is mainly for adjusting; appetite often drops early.
- Months 2 to 5: the dose increases by 2.5 mg about every four weeks, and weight loss picks up.
- Month 5 and beyond: most people reach a maintenance dose between 5 and 15 mg, chosen with their prescriber.
How dosing works
Compounded tirzepatide is often prepared at 15 mg/mL with vitamin B6. Doses start low and step up about every four weeks.
Compounded tirzepatide is often prepared at 15 mg/mL with vitamin B6 (pyridoxine) 10 mg/mL, for each patient under a prescription. Doses are measured with a standard U-100 insulin syringe.
| Vial size | Strength | Tirzepatide per vial | Vitamin B6 per vial |
|---|---|---|---|
| 2 mL | 15 mg/mL | 30 mg | 20 mg |
| 4 mL | 15 mg/mL | 60 mg | 40 mg |
Typical dose schedule
- 2.5 mgWeeks 1–417 units
- 5 mgWeeks 5–833 units
- 7.5 mgWeeks 9–1250 units
- 10 mgWeeks 13–1667 units
- 12.5 mgWeeks 17–2083 units
- 15 mgWeek 21 on100 units
Increase only as directed by your prescriber.
See every dose and how long a vial lasts
| Weekly dose | Amount | Syringe | 2 mL vial lasts | 4 mL vial lasts |
|---|---|---|---|---|
| 2.5 mg | ≈0.17 mL | 17 units | 12 wks | 24 wks |
| 5 mg | ≈0.33 mL | 33 units | 6 wks | 12 wks |
| 7.5 mg | 0.50 mL | 50 units | 4 wks | 8 wks |
| 10 mg | ≈0.67 mL | 67 units | 3 wks | 6 wks |
| 12.5 mg | ≈0.83 mL | 83 units | 2.4 wks | 4.8 wks |
| 15 mg | 1.00 mL | 100 units | 2 wks | 4 wks |
Approximate supply, once weekly. Your prescriber sets your dose and any custom schedule.
Tips for success
- Protein and strength training help protect muscle.
- Smaller meals reduce nausea, especially after dose increases.
- If side effects are hard to manage, your prescriber can keep you at a dose longer before increasing.
Sources
- Jastreboff AM, et al. Tirzepatide once weekly for the treatment of obesity (SURMOUNT-1). New England Journal of Medicine, 2022.
- Aronne LJ, et al. Tirzepatide as compared with semaglutide for the treatment of obesity (SURMOUNT-5). New England Journal of Medicine, 2025.
- Aronne LJ, et al. Continued treatment with tirzepatide for maintenance of weight reduction (SURMOUNT-4). JAMA, 2024.
