How often is tirzepatide dosed?

Once-weekly, by subcutaneous injection

In the trials and on the FDA-approved label, tirzepatide is administered once weekly by subcutaneous injection. Its half-life is approximately 5 days, which supports the once-weekly interval, with steady state reached in about 4 weeks at each dose level.

The titration the trials used

Rather than starting at the target dose, the FDA-approved schedule (the SURMOUNT-1 protocol) raises the dose every 4 weeks over 20 weeks, all once weekly:

• Weeks 1–4: 2.5 mg once weekly (initiation dose).
• Weeks 5–8: 5 mg once weekly.
• Weeks 9–12: 7.5 mg once weekly.
• Weeks 13–16: 10 mg once weekly.
• Weeks 17–20: 12.5 mg once weekly.
• Weeks 21+: 15 mg once weekly (maximum dose).

Maintenance and why it titrates slowly

Maintenance doses in the trials were 5, 10, or 15 mg once weekly. The slow titration is used to reduce gastrointestinal side effects; faster escalation was reported to increase side-effect rates without improving outcomes.

To convert a mg dose to syringe units and plan reconstitution, the Prof. Peptide dosage calculator.

• Frequency: once weekly, subcutaneous.
• Titration: dose raised every 4 weeks (2.5 → 5 → 7.5 → 10 → 12.5 → 15 mg) over 20 weeks.
• Maintenance: 5, 10, or 15 mg once weekly.
• Half-life ~5 days; steady state in ~4 weeks per dose level.

For the adverse events reported alongside this schedule, see tirzepatide side effects.