Retatrutide Half-Life & How Long It Lasts
Last updated 13 June 2026
Quick answer
What "half-life" means
Half-life is the time it takes for the body to clear half of a substance. A short half-life means it leaves fast, so you would need it often. A long half-life means it stays around, so you need it less often.
Why retatrutide is once-weekly
Because retatrutide's half-life is around six days, one dose keeps a useful level in the body for about a week. That is why trials use a once-weekly schedule. It is built to last longer than older, daily peptides.
How this links to dosing
A long half-life is also why trial doses are raised slowly, step by step. It takes time for levels to settle. See dosing in studies for more.
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What is retatrutide's half-life?+
Retatrutide has a long half-life — roughly six days. That is why it is given just once a week in clinical trials.
Why does half-life matter?+
Half-life tells you how long a peptide stays active in the body. A long half-life means fewer doses are needed to keep a steady level.