A few years ago Matt Kaeberlein, the director of the healthy aging and longevity research institute at the University of Washington, started suffering through the agonizing pain of a frozen shoulder. He says he was having trouble sleeping, was feeling "pissed off and depressed," and "couldn't go throw a ball" with his kid the way he used to.
Kaeberlein — 49 at the time — had a hypothesis about what was going wrong with his body. "I got to thinking: This is an age-related inflammatory condition," he told Insider. That insight led him to one possible solution: a little-known drug called rapamycin.
At work, Kaeberlein studies how the drug, an immune-suppressing agent typically prescribed to organ-transplant recipients and cancer patients, may help people age more gracefully — keeping muscles pain-free, brains sharp, even fighting off viruses.
So Kaeberlein tried rapamycin out on himself, in what he acknowledges was a loosely controlled "self-experiment" to heal his shoulder.
What he experienced over the course of about 2 ½ months taking rapamycin weekly "made me a believer" in the drug, he said. "I'd say 90% range of motion was back, and the pain was probably 90% gone — and it hasn't come back."
Now he takes rapamycin, which costs about $1 per pill, on a cyclical schedule, dosing himself in 10- to 12-week increments every six to eight months or so in the hopes of keeping age-related inflammation away.
Rapamycin has been shown to slow aging in flies, worms, and mice
To date, Kaeberlein has tracked how more than 330 people taking rapamycin feel taking the medication off-label to try to combat aging. Many say they feel great, with less stomach pain and less anxiety than their peers.
It's possible the rapamycin may be having some antiaging effects, reducing age-related inflammation issues as diverse as dementia, cancer, or simple muscle aches and pains. But we don't know for sure.
In mice, rapamycin's track record is more proven. The antifungal compound — first discovered in a clump of dirt on the remote island of Rapa Nui, or Easter Island — is a well-known life-extender for flies, worms, and mice. It targets a key protein in the body that regulates and promotes cellular reproduction, dialing it down, and discouraging growth — much like fasting.
"Rapamycin is pretty good — in mice — at knocking down age-related inflammation," Kaeberlein told Insider.
We don't know the risks of taking rapamycin for aging — or the best dosage for people
Though Kaeberlein's personal experiment felt like a success, he told Insider that for now, we can't say how beneficial, or risky, rapamycin may be when taken in small doses to combat aging in our cells.
His data suggests that one of the most common side effects users experience is fairly benign: canker sores in the mouth.
But no one has developed a clear protocol for how to take rapamycin as an antiaging drug yet. Kaeberlein developed his own rapamycin routine based on what happens in lab mice.
"I don't have a great rationale, honestly — I kind of try different things," he said.
Other biohackers take the drug more regularly, popping it once a week — just because a 2014 study by Novartis suggested that could be a better strategy than daily.
Longevity experts stress anyone who's on rapamycin should be under the strict supervision of a doctor. Because while rapamycin can boost elder immunity to viral diseases like the flu — and could maybe have a similar effect on COVID — it could also impair some aspects of immune function, and may make people more susceptible to bacterial infections.
Kaeberlein says that for now, his favorite tried-and-true tips for aging well are still the ones you've heard many times before: Eat a balanced diet, exercise, and sleep well.
"If you had to pick one thing that's probably the best," he said, "at least for functional aging, it's exercise."
