Rapamycin for longevity: the trials, the dose and the risks

Rapamycin is the drug longevity researchers talk about most, and for a good reason: it extends lifespan in mice more reliably than almost anything else tested. In people, the evidence is far earlier. One year-long trial found low weekly doses relatively safe, but it did not change its main outcome, and no human study has measured lifespan. Rapamycin is also a real immunosuppressant with a boxed warning, which is why the dose and the monitoring matter.

What rapamycin is

Rapamycin, also called sirolimus, blocks mTOR, a protein that tells cells to grow and divide when nutrients are plentiful. The FDA approved it as Rapamune to prevent organ rejection in kidney transplant patients aged 13 and older, and it is also approved for lymphangioleiomyomatosis (LAM), a rare lung disease. Generic sirolimus tablets are widely available. Other sirolimus products are approved for a rare tumor (Fyarro) and, as a gel, for facial angiofibroma in tuberous sclerosis (Hyftor).

Prescribing it to slow aging is off-label. A clinician may legally do that with an approved drug, but no FDA review has found that rapamycin slows aging.

The animal evidence

In a landmark 2009 study run at three separate test sites, genetically varied mice fed rapamycin starting at 600 days of age, late in a mouse’s life, lived longer. Measured at the age when 90% of mice had died, lifespan rose by 14% in females and 9% in males. A second group started at 270 days also lived longer. The treated mice didn’t die of different diseases, and the authors suggested rapamycin might work by postponing cancer, slowing aging, or both.

Blocking the same mTOR pathway also extends lifespan in yeast, worms and flies, and that consistency is why rapamycin attracts so much attention. But mice in a lab aren’t people, and a drug that helps a mouse live 9% to 14% longer has not been shown to do anything similar in humans.

The human evidence

PEARL: the longest trial in healthy adults

The PEARL trial, published in the journal Aging in 2025, is the largest randomized, placebo-controlled study of rapamycin for healthy aging so far. It ran for 48 weeks, was decentralized and double-blinded, and gave participants placebo, 5 mg or 10 mg of compounded rapamycin once a week. The trial’s preprint equates those doses to about 1.43 mg and 2.86 mg of generic rapamycin.

What it found:

• Adverse events and serious adverse events were similar across all groups, and blood biomarkers stayed in normal ranges.
• Visceral fat, the main outcome, did not change.
• Women taking 10 mg gained lean tissue mass and reported less pain.
• People taking 5 mg reported better emotional well-being and general health.
• No other measures changed significantly.

The authors’ conclusion was careful: low-dose intermittent rapamycin was “relatively safe” over 48 weeks, and future work will test a broader range of doses.

What PEARL can and can’t tell you

PEARL is a useful first step with clear limits. AgelessRx, which sells rapamycin, says its researchers designed and led the trial, which enrolled healthy adults aged 50 to 85. It used compounded rapamycin, so its doses don’t translate one to one to generic tablets. The positive findings came from subgroups, such as women on 10 mg, rather than from the main outcome, and subgroup results need confirming in a larger trial before anyone should rely on them. AgelessRx reports that mild stomach symptoms and mouth sores were the most common side effects in PEARL, affecting roughly 1 in 5 participants, and the published paper found adverse events similar across the rapamycin and placebo groups.

Immune studies with a related drug

Two earlier trials used everolimus, a close cousin of rapamycin. In a 2014 study in older volunteers, everolimus at relatively well-tolerated doses improved the response to flu vaccination by about 20%. In a 2018 phase 2a trial in 264 older adults, 6 weeks of low-dose everolimus combined with a second mTOR inhibitor was followed by fewer reported infections over the next year. These results are often cited for rapamycin, but they used different drugs.

What no study has shown

No human trial has shown that rapamycin extends lifespan, delays age-related disease, or slows a validated measure of aging. The human studies are short, small by the standards of drug trials, and measure markers rather than hard outcomes.

How longevity clinics dose it

Transplant patients take sirolimus every day to keep the immune system suppressed. Longevity clinics usually prescribe a low dose once a week instead, on the idea that an intermittent dose gives the body time to recover between doses. That approach comes from animal research and from PEARL; it hasn’t been compared head to head with other schedules in people.

The form matters as much as the milligrams. Healthspan prescribes FDA-approved generic enteric-coated tablets by default and says compounded capsules can absorb poorly. AgelessRx offers both compounded and generic rapamycin and reports, from blood levels in 44 commercial and 23 compounded users, that its compounded rapamycin is roughly a third as bioavailable per milligram, which is why compounded doses are usually higher. A 5 mg compounded capsule and a 5 mg generic tablet aren’t the same dose.

The risks

The sirolimus label carries a boxed warning: increased susceptibility to infection and the possible development of lymphoma may result from immunosuppression. It also warns against use in liver or lung transplant patients. Those warnings come from daily transplant doses, usually taken with other immunosuppressants; the risks at low weekly doses are less well measured.

The label’s other warnings include:

• High cholesterol and triglycerides
• Slow wound healing and fluid build-up, which matters before surgery
• Lung inflammation and protein in the urine
• Skin cancer
• Reduced male fertility and harm to a developing baby
• Avoiding live vaccines while on the drug

Strong CYP3A4 inhibitors and inducers, including some antibiotics and antifungals, and grapefruit juice change sirolimus blood levels. AgelessRx lists mouth sores, nausea, diarrhea, headache, changes in cholesterol, more infections and slower wound healing as possible side effects at longevity doses. Both clinics we compare build lab monitoring into the price for this reason.

What it costs online

As of October 2026, the two clinics in our comparison that prescribe rapamycin charge the same:

Step-by-step details on the intake, labs and prescription are in how to get rapamycin online, and the full drug facts are on our rapamycin treatment page. Our longevity clinic rankings compare both clinics with the rest of the field.

Who should think twice

The label’s warnings matter most for anyone with a weakened immune system or frequent infections, a history of lymphoma or skin cancer, planned surgery, pregnancy or plans for pregnancy, and men hoping to father children. Raise each of these with the prescriber before starting. Anyone taking medicines that interact through CYP3A4 needs a careful review. A clinician who orders baseline labs and repeats them is doing what the label’s warnings call for.

The bottom line

Rapamycin has the strongest animal case of any longevity drug and a short, cautious human record: one 48-week trial found low weekly doses relatively safe but missed its main outcome. It is an immunosuppressant with a boxed warning, and the difference between compounded and generic forms changes the real dose. If you and a clinician decide to try it, choose a program that checks your labs before and during treatment, and treat it as an experiment rather than a proven anti-aging therapy. For other options, see the longevity hub.