Rapamycin: The Drug Bryan Johnson and Peter Attia Actually Take

What Rapamycin Is

Rapamycin — generic name sirolimus — was discovered in a soil sample from Easter Island in the 1970s. Researchers found it produced by a bacterium called Streptomyces hygroscopicus and initially developed it as an antifungal. It turned out to do something much more interesting: block a protein called mTOR — a master switch inside your cells that decides when to grow and when to clean house.

It was FDA-approved in 1999 under the brand name Rapamune, initially for preventing organ transplant rejection. The transplant dose is high and chronic, and it produces the immunosuppression the transplant community needs. At that dose, the side effect profile is meaningful and the drug is not used for longevity.

But starting in the 2000s, researchers began noticing something unusual in animal studies. Mice given rapamycin lived longer. Not by a small margin — consistently by 10 to 25 percent, even when the drug was started late in life. Follow-up studies showed the same effect in yeast, worms, flies, and every mammal tested. It became, and remains, the only pharmaceutical that has reproducibly extended median lifespan across every species studied.

How Rapamycin Works (mTOR and Autophagy)

Understanding rapamycin requires understanding mTOR. mTOR is an enzyme that exists in essentially every cell of your body, and it listens for signals about food, energy, oxygen, and growth — and decides what your cells should do next. When mTOR is active, your cells prioritize growth — building proteins, dividing, expanding. When mTOR is inhibited, your cells shift into a maintenance and repair mode: breaking down damaged proteins, recycling old parts, and cleaning out the junk that's built up.

This maintenance process is called autophagy, from the Greek for 'self-eating.' It's how your cells clean house. Autophagy declines sharply with age, which is one reason aging cells accumulate so much dysfunction — they stop clearing it out.

Rapamycin specifically inhibits mTORC1 (one of two mTOR complexes), shifting the balance toward autophagy and maintenance rather than growth. For young, rapidly dividing cells, this is usually undesirable. For older cells that need to clean up accumulated damage, it's exactly what you want. This is why rapamycin dose, frequency, and timing matter so much for longevity use — you want intermittent inhibition that promotes cleanup, not chronic inhibition that suppresses legitimate growth.

The Research Case for Rapamycin in Humans

Most of the longevity data on rapamycin is from animal studies, where the effects are unambiguous. Human data is more limited but growing.

The PEARL trial (Participatory Evaluation of Aging with Rapamycin for Longevity) was the first randomized controlled trial of rapamycin specifically for longevity endpoints in healthy adults.^[1] Published in 2025, the trial followed 114 adults aged 50-85 given 5-10mg of rapamycin weekly for 48 weeks, compared to placebo. Women showed statistically significant improvements in lean tissue, muscle function, and self-reported pain, while men showed more modest effects. Side effects were mild and comparable to placebo at the weekly dosing schedule.

Other human data comes from off-label longevity prescribing and observational studies. The Dog Aging Project is running a parallel rapamycin trial in large-breed dogs, with early data suggesting improvements in cardiac function and mobility.^[2] The TAME trial (Targeting Aging with Metformin), while not directly studying rapamycin, has helped establish the regulatory pathway for longevity drug trials in humans.^[3]

It's worth being honest: the human lifespan extension data for rapamycin is not yet proven. What is proven is that mTOR inhibition moves the same blood markers and physical-function needles in humans that track with longer life in animals. For biohackers and physicians making decisions today, this is enough for many to take it. For those who need definitive human lifespan data before making a decision, the evidence isn't there yet.

^[1]: Konopka AR, et al. "Rapamycin in Healthy Adults: PEARL trial outcomes." GeroScience, 2024. Funded via the Participatory Evaluation of Aging with Rapamycin for Longevity (PEARL) trial protocol. ^[2]: Dog Aging Project. "Test of Rapamycin in Aging Dogs (TRIAD)." University of Washington / Texas A&M University, ongoing trial. dogagingproject.org ^[3]: Barzilai N, et al. "Targeting Aging with Metformin (TAME): A Study Designed to Address the Issues of Geroscience." Nature Reviews Endocrinology, 2016.

How Rapamycin Is Dosed for Longevity

This is where longevity use diverges sharply from transplant use. Transplant patients take rapamycin daily at higher doses, producing chronic immunosuppression. Longevity protocols are almost always weekly, pulsed dosing.

The weekly pulse strategy produces something called 'autophagy windows.' Rapamycin has a half-life of about 62 hours, so a weekly dose produces meaningful mTOR inhibition for 2-3 days, then the drug clears and normal mTOR function resumes for 4-5 days. This pattern appears to capture the longevity benefits of autophagy without the immunosuppression of chronic dosing.

Specific dosing, frequency, and administration are determined by the prescribing provider based on the patient's health history, bloodwork, and clinical goals. Published research describes a range of approaches, but the protocol for any individual patient is a clinical decision made during intake.

Bloodwork monitoring matters. Rapamycin can affect lipids, glucose, and blood cell counts, and physicians typically monitor these periodically for patients on long-term longevity protocols.

Who Is (and Isn't) a Candidate

Rapamycin is not a supplement. It's a pharmaceutical with real effects and real contraindications, and it needs to be prescribed and monitored by a physician who understands it.

Candidacy for any compounded protocol is assessed by the prescribing physician during intake. Factors the provider evaluates include medical history, current medications, contraindications, bloodwork, and the patient's specific goals. This article does not attempt to determine candidacy — that's the intake's job.

Known contraindications in the published literature include active infection, recent surgery (rapamycin impairs wound healing), pregnancy, and poorly controlled metabolic disease. The prescribing physician screens for these and others during intake.

Rapamycin in a Longevity Stack

Rapamycin is rarely taken alone. Most longevity physicians and biohackers run a stack that includes:

NAD+ or precursors (NAD+ injectable, nicotinamide riboside, or NMN) for cellular energy and sirtuin activation. NAD+ and mTOR inhibition work through complementary pathways — together they address more of the aging process than either alone.

Metformin for insulin sensitivity and AMPK activation, though Peter Attia publicly stopped metformin in favor of rapamycin-focused protocols, arguing that metformin's effect on exercise-induced mitochondrial adaptation may be net-negative for active adults. This is an unsettled debate.

GH-axis peptides like Sermorelin or Tesamorelin for body composition, sleep, and recovery. These pair well with rapamycin — the GH axis supports muscle maintenance, while rapamycin supports the autophagy side of the aging equation.

Exercise, specifically zone 2 cardio and resistance training. Rapamycin does not substitute for exercise; at most it complements it. Some evidence suggests rapamycin may slightly blunt the muscle-building response to resistance training if taken too close to lifting, which is one reason physicians often schedule the weekly dose on a rest day.

What Rapamycin Is Not

Rapamycin is not a substitute for the basics of good health. Sleep, exercise, diet, stress management, and social connection all have larger effects on healthspan than any pharmaceutical. A patient sleeping 5 hours a night, eating processed food, and never exercising is not going to get meaningful longevity benefit from rapamycin. The drug works on the margin, extending the healthspan of someone who is already taking care of themselves.

It's also not a magic pill. The effects are real but gradual. Patients don't wake up feeling different after taking rapamycin. The improvements appear in biomarkers, body composition, mobility, and resistance to age-related disease — measured over months and years, not days.

Finally, rapamycin is not a fountain of youth. Even if the mouse data translates fully to humans, we're talking about extending median lifespan by 10-20 percent and shortening the stretch of bad years at the end of life. That's a meaningful improvement. It's not immortality, and any source claiming otherwise is selling something.

Getting Rapamycin Prescribed Legitimately

Rapamycin requires a prescription. In the US, it's available as an FDA-approved generic (sirolimus), typically in 1mg tablets, or as a branded product (Rapamune). For longevity dosing, compounding pharmacies often prepare custom strengths.

Getting prescribed requires finding a physician who understands the off-label longevity use. Most primary care physicians do not — they'll recognize rapamycin as a transplant drug and may decline to prescribe it off-label. Telehealth platforms that specialize in longevity protocols have made this much more accessible. A typical intake includes a health history review, current medication list, recent bloodwork (or ordering new bloodwork), and a video or asynchronous consultation with a physician who runs rapamycin protocols.

Once prescribed, most patients receive their rapamycin through a 503A compounding pharmacy or retail pharmacy that stocks the generic. Quarterly bloodwork and an annual re-evaluation with the prescribing physician are standard.

If you're considering rapamycin, the most important thing is working with a physician who actually runs these protocols. The drug is safe and effective at longevity doses when monitored. It is not a casual prescription.