Does Rapamycin Have Potential as an Anti-Aging Drug?

A drug discovered in the soil of a remote Pacific island in 1964 could slow down the aging process. It sounds like something straight out of a pharmaceutical fever dream, but this isn’t science fiction.

Meet: rapamycin. This compound, also known as sirolimus, has captured our imaginations as an anti-aging drug. But does it have potential as a longevity elixir?

The Origins of Rapamycin

Rapamycin was first an obscure immunosuppressant drug for organ transplants. It wasn’t until the 2000s that researchers discovered it could extend the lifespan of mice, worms, flies, and yeast.

• Science Says: A 2016 study found that giving mice rapamycin extended their lifespan by 2 months. The final rodent survivor died more than two years after the experiment at 3 years and 8 months. That’s about 140 in human years!

What Rapamycin Does in the Body

This probably sounds like snake oil to you (it did for me at first, too), so let me explain rapamycin’s biological effects.

Basically, rapamycin tricks your body into caloric restriction mode. This is when you eat fewer calories, but your body becomes more efficient and resilient.

• Zoom In: This is an evolutionary survival trick. When food is limited, your body assumes tough times are ahead, and your cells shift focus to repair and cleanup instead of building new tissue.

“How does rapamycin do this?” It blocks a cellular pathway called mTOR (mammalian* target of rapamycin). Think of mTOR as a switch. When it’s turned off, the body goes into survival mode. Rapamycin flips that switch off.  

The Science of Rapamycin on Humans

Human trials with rapamycin aren’t testing for longevity. That would be almost logistically impossible. Instead, scientists are looking at whether rapamycin improves our body’s systems, like immunity and skin health, over time.

The science has found:

• Immune Boosting. A 2014 study found that low doses of rapamycin-like drugs boosted flu vaccine responses in elderly people by 20%. (NOTE: Dose matters. A high dose was found to weaken immunity.)
• Improved Skin: In 2019, researchers found that topical rapamycin cream applied to aging hands for 6-8 months reduced “zombie cells” and increased collagen production, leading to fewer wrinkles and more dermal volume.
• Heart Health: A study of 10 people with severe heart disease found that everolimus, a rapamycin-like drug, improved heart function over 6 months. (NOTE: Larger studies are needed to better understand rapamycin’s effect on heart health.)

The Cons of Rapamycin

They include:

• Physical Side Effects: Mucosal ulcers, rashes, delayed wound healing, elevated cholesterol and triglycerides, low blood cell count, and menstrual problems.
• Drug and Food Interactions: Rapamycin is broken down by liver enzymes (CYP3A4) and cleared by transport proteins (P-glycoprotein). If these are blocked by antibiotics, antifungal drugs, or even grapefruit juice, rapamycin can build up in your system, raising the risk of nasty side effects.
• Dampens Immunity: Rapamycin weakens your immune system’s ability to safely handle live vaccines (e.g., measles, mumps, rubella, etc).  

Should A Woman Over 50 Take Rapamycin?

Here’s my sober view: If you’re curious, treat this as a clinical experiment (not a solo biohack). That means:

1. Partnering with a credentialed physician who understands mTOR inhibitors.
2. Nailing the health fundamentals. Sleep, protein, resistance training, blood pressure, lipids, and glucose control move the longevity needle most.
3. Creating a proper protocol. Low intermittent doses, baseline labs plus regular monitoring for lipids and glucose, a review of drug interactions, smart vaccine timing, and no elective surgery during initiation.

If you expect a miracle, you’ll be disappointed. If you expect a careful test of a plausible aging target, you’ll be aligned with the actual science.

That said? It’s still early days for rapamycin. There are many clinical trials underway, including tests on muscle strength and endurance in older adults, ovarian aging, Alzheimer’s, and more. I’ll keep you updated on the latest science as soon as it’s fresh off the press.

If you’d like to ask me your questions directly, go to my Instagram.

Important Clarification: Rapamycin

*I've gotten a few questions from Ajenda readers about the terminology of mTOR in the article I wrote about Rapamycin.

Our medical editing team and I wrote it using the newer terminology, m = mechanistic,  though I thought I actually should have used the more familiar m = mammalian terminology that most of the older literature uses.

Though a few readers may have interpreted this as an error, it's really a great example of shifting terminology, prompted by new information. I researched the change in terminology and wanted to share it with you:

• mTOR originally stood for “mammalian target of rapamycin.” That was the name given when it was first described in the early 1990s, because rapamycin was the compound that inhibited it, and it was identified in mammals as the analog of a yeast protein (TOR).
• Around 2009, the field began formally shifting terminology. The official update came from the HUGO Gene Nomenclature Committee and IUPHAR (the receptor nomenclature authority). They endorsed “mechanistic target of rapamycin” to reflect that mTOR is the central kinase in the TOR signaling pathway, regardless of species.
• Journals and review papers started adopting it, though many would put both terms for a while: mTOR (mechanistic, formerly mammalian, target of rapamycin). Today, the preferred and more accurate term is “mechanistic target of rapamycin.
• The reasoning is that the pathway is highly conserved across species, not just mammals. To avoid species-specific language, the nomenclature was updated.  

So, if you’re writing for a modern scientific or medical context (or Ajenda's Newsletter) the correct terminology is: mTOR = mechanistic target of rapamycin.  That said, you’ll still see mammalian in older literature or in casual conversation. But journals, conferences, and most researchers use mechanistic now.

Thanks to Dr. Avrum Bluming, author of  the great book, Estrogen Matters, for emailing me about this terminology. I would have been outdated by using the term I wanted to initially use (mammalian) but fortunately our incredible newsletter editor was even more current than I, and corrected it to the modern, more current term (mechanistic)!