Rapamycin and longevity: what the research describes (and why we don't tell you how to dose it)

Rapamycin (sirolimus) is a prescription-only medicine licensed in the UK for organ-transplant immunosuppression and certain rare conditions. It is the most-cited single compound in the contemporary longevity discussion, partly because it has the most consistent record of any drug at extending lifespan in mice.

This page describes what the research reports. It is not dosing guidance, and the legal route to obtain rapamycin in the UK is a clinical indication and a prescription, not online suppliers.

The mouse evidence#

Rapamycin is the only drug that has reproducibly extended lifespan across multiple mouse strains, including when started in middle and old age. The National Institute on Aging Interventions Testing Programme (ITP), a triple-blind multi-site programme, has shown median lifespan extensions of 9–14% in male mice and 14–21% in female mice across multiple cohorts.

Effects extend beyond raw lifespan. Mouse studies have shown improvements in:

• Cardiac function in aged hearts
• Immune function (a paradoxical finding given rapamycin's classical immunosuppressant role)
• Memory in some models
• Tissue-specific markers of cellular ageing

The mechanism#

Rapamycin inhibits mTOR (mechanistic target of rapamycin), a signalling hub that integrates nutrient, energy, and growth signals. Inhibiting mTOR mimics some effects of caloric restriction, increases autophagy, and reduces protein synthesis. Whether the longevity effect is "caloric-restriction mimicry" or something different is debated.

Continuous high-dose rapamycin produces immunosuppression. The longevity work uses intermittent (e.g. weekly) dosing, in which acute immunosuppression is much smaller and other effects may dominate.

Human evidence so far#

Direct human longevity trials are absent. Available evidence:

• Mannick et al. trials (Novartis, then resTORbio): older adults given rapamycin analogues (everolimus) at low doses, intermittently, showed modest improvements in flu vaccine response. Small trials.
• PEARL trial — independent, placebo-controlled trial of weekly rapamycin in healthy adults aged 50–85. Reported in 2024 with mixed results: small improvements in some functional measures, no dramatic effect.
• Observational data from transplant patients (chronic high-dose): these patients face many confounders (transplant context, other immunosuppressants) so are hard to interpret for longevity-context dosing.

The honest summary: in humans, the available trial data are short, small, and show subtle effects on a few markers. They do not demonstrate lifespan extension and are nowhere near the level of evidence behind exercise or smoking cessation.

Side effects to know about#

Even intermittent low-dose rapamycin carries risks documented from clinical use:

• Impaired wound healing
• Mouth ulcers (stomatitis)
• Acne and skin issues
• Lipid elevations (cholesterol, triglycerides)
• Insulin resistance / hyperglycaemia in some patients
• Reduced immune response; vaccine timing matters
• Edema
• Theoretical infection risk

Drug interactions are extensive. Rapamycin is metabolised by CYP3A4 and interacts with many medications, including statins, calcium-channel blockers, and macrolide antibiotics. Grapefruit interacts.

UK regulatory reality#

Rapamycin is a prescription-only medicine. The licensed indications in the UK do not include "longevity" or "ageing". Obtaining it for longevity purposes legally requires a UK-licensed prescriber willing to prescribe off-label, with informed consent and monitoring.

Online sources advertising rapamycin for personal import are operating outside UK medicines law. Quality control on grey-market pharmaceuticals is unreliable; independent testing has repeatedly found incorrect dose, wrong compound, or contamination.

Why we won't give dosing#

Because dose, frequency, monitoring, and contraindications depend on individual factors (age, medications, conditions, infection risk, vaccination status) that a website can't assess, and because rapamycin in a longevity context is firmly an experimental, prescription-supervised intervention. People interested should speak to a UK-licensed clinician who specialises in age-management medicine, with clear-eyed awareness of how much we still don't know.

The honest read#

Rapamycin is the longevity drug with the strongest mouse data and the most active human research. It's also a real medicine with real side effects, illegally sourced for longevity by some people, and prescribed off-label by some clinicians. None of those facts make it a wellness supplement. The evidence base for "should I take this" is currently far weaker than people enthusiastic about the mouse data want it to be.