What is rapamycin?
Sirolimus
Rapamycin is a prescription drug that turns down mTOR, the cell's growth switch; it's used to prevent organ transplant rejection and is studied as a possible anti-aging drug.
If mTOR is a construction foreman shouting "build!", rapamycin is someone gently turning down his megaphone, so crews spend more time on repairs.
Why it matters for aging
Rapamycin was discovered in soil bacteria from Easter Island, called Rapa Nui, which gave it its name. In medicine it's used at higher daily doses to suppress the immune system after transplants, which is why side effects such as mouth sores and higher infection risk need medical monitoring.
Longevity researchers study low, intermittent doses, hoping to get the repair benefits of lower mTOR without the immune side effects. It's a prescription drug and not something to experiment with without a doctor.
A common myth
Rapamycin is a proven anti-aging drug for humans.
It extends lifespan in mice, even when started late in life. In humans, a 2025 trial of low weekly doses found it safe over a year but with only modest, mixed benefits. There's no evidence yet that it extends human life.
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Updated Nov 9, 2026 · All terms