These are the two most discussed prescription drugs in longevity medicine. They work very differently, and the quality of evidence behind each is often overstated.
| Rapamycin | Metformin | |
|---|---|---|
| Primary target | mTOR | Liver glucose output / AMPK |
| Animal lifespan | Strong, replicated | Mixed |
| Human longevity data | Small trials, no outcomes | Observational; TAME pending |
| Regrowth grade | C | B |
| Typical cost | $30–$150/mo | $5–$20/mo |
The case for rapamycin
No compound has a more consistent record of extending lifespan in mice — including when started in middle age. The open question is whether intermittent low doses in humans capture that benefit without the immune downsides seen at transplant doses.
The case for metformin
Decades of safety data and a low price. But some evidence suggests it can blunt muscle and fitness gains from exercise in older adults — a meaningful trade-off for people who train.
Bottom line
Neither is proven to extend human life. Anyone considering either should do so with a clinician, baseline labs and ongoing monitoring.