How is retatrutide dosed in research?

What the trials administered

The Phase 2 program tested weekly doses from 0.5 mg to 12 mg. The Phase 3 TRIUMPH program escalates in four-week steps — 2 mg, then 4 mg, then 6 mg, then 9 mg, with 12 mg as the highest maintenance dose tested. Half-life is approximately six days, which is the pharmacokinetic basis for the once-weekly interval, with steady state reached across four to five weeks at each level.

The escalation is not incidental to the protocol. Phase 2 data showed that beginning at 4 mg rather than titrating up increased gastrointestinal side-effect rates without improving outcomes, which is why the trials step rather than start high.

Why there is no approved dosing standard

Retatrutide has no marketing approval in any jurisdiction, so there is no prescribing information, no label-established dose, and no regulator-reviewed dosing standard. Every figure above is a trial protocol figure — what was administered to enrolled participants under supervision, reported here as what the research used. Material sold as research-use-only carries no dosing instructions of any kind.

To convert any of these milligram figures into syringe units for a given vial and volume, use the dosage calculator.

What the same trials reported alongside those doses

The dose figures above came out of trials that also reported what those doses did. Gastrointestinal effects dominated and tracked with dose: nausea affected up to 60% of participants at 12 mg in Phase 2, and diarrhea 15–33%. Dysesthesia — altered skin sensation, described as tingling or pins-and-needles — was reported in about 21% at the 12 mg dose in TRIUMPH-4, and is specific to retatrutide rather than shared with semaglutide or tirzepatide. Those rates are why the trials escalated the dose in four-week steps instead of starting high.

The full adverse-event profile from these trials, with rates by dose, is on the compound profile: retatrutide side effects.

• Phase 2: 0.5 mg to 12 mg weekly, subcutaneous.
• Phase 3 TRIUMPH: 2 mg start, escalating every four weeks.
• TRIUMPH-4 tested 9 mg and 12 mg as maintenance doses.
• Approximately six-day half-life; once-weekly administration.
• No approved label, and therefore no approved dosing standard.