Rapamycin: the mTOR inhibitor with the strongest animal lifespan data

What it means

Rapamycin (sirolimus) is a macrolide discovered in soil from Easter Island (Rapa Nui) in the 1970s. It inhibits mTOR complex 1, the nutrient-sensing kinase that drives growth, and is licensed as an immunosuppressant for kidney-transplant recipients and for a rare lung disease. Analogues (everolimus, temsirolimus) are cancer drugs.

In longevity use it is taken "off-label" at low, intermittent doses — typically once a week — on the theory that pulsed mTORC1 inhibition captures the benefit while sparing mTORC2 and the immune system.

Why it matters for longevity

It is the only pharmacological intervention that has repeatedly extended lifespan in a mammal under independent, multi-site testing, and it works when started late in life. That makes it the benchmark against which every other longevity-drug claim is measured.

What the evidence says

The NIA Interventions Testing Program found rapamycin extended median lifespan in mice by 9–14% (Harrison 2009), reproduced across three sites and in later dose-response studies, even when started at 20 months (about 60 human years). Mice also showed delayed cancers and improved tendon, heart and cognitive measures. In companion dogs, the TRIAD trial is ongoing after a pilot showed improved cardiac function.

In humans: Mannick 2014 and 2018 showed low-dose mTOR inhibitors improved influenza-vaccine response in older adults by about 20% and reduced infections. The PEARL trial (2023, 114 adults, 5–10 mg weekly for a year) was safe and reported modest gains in lean mass and self-reported pain in women, no change in the primary outcome. No human lifespan or disease-prevention trial exists. Known effects at transplant doses: mouth ulcers, raised lipids and glucose, impaired wound healing, immune suppression; at weekly low doses the PEARL side-effect profile was mild.

How to measure or use it

• Prescription-only, and a physician decision; the longevity dosing (typically 3–8 mg once weekly) is extrapolated, not trial-derived.
• Markers worth watching on it: fasting glucose and HbA1c, lipids (ApoB), a full blood count, and mouth-ulcer frequency.
• The physiological mTOR levers — fasting windows, endurance training, body-fat control — come first and cost nothing.

Related

• The longevity drugs — the full article, with dosing debates and side effects
• Muscle mass and ageing — the trade-off against mTOR-driven muscle
• The longevity protocol — where a prescription decision sits in a plan