What it means
A senolytic is any agent that kills senescent cells while leaving normal cells alone. Senescent cells survive by over-using anti-apoptosis pathways (BCL-2, PI3K/AKT, p53 regulators); senolytics briefly block those pathways so the cells tip into programmed death. The term was coined in 2015 by Kirkland and colleagues at the Mayo Clinic.
The best-studied agents are the combination dasatinib (a leukaemia drug) plus quercetin (a flavonoid), fisetin (another flavonoid), and navitoclax (a BCL-2 inhibitor). Senolytics are typically given in short "hit-and-run" courses — a few days, repeated monthly — because the aim is clearance, not continuous exposure.
Why it matters for longevity
If senescent-cell accumulation drives inflammaging and tissue decline, periodically clearing them could slow several age-related conditions at once. That is the hypothesis; the mouse data support it; the human data have not yet tested it properly.
What the evidence says
In mice, dasatinib plus quercetin improved physical function and extended post-treatment survival by about 36% when started in old age (Xu 2018, Nature Medicine). Fisetin extended lifespan in aged mice by roughly 10% (Yousefzadeh 2018).
In humans: Justice 2019, 14 patients with idiopathic pulmonary fibrosis, dasatinib + quercetin for three weeks, improved six-minute walk, no control. Hickson 2019, 9 patients with diabetic kidney disease, reduced senescent markers in fat tissue after three days. Several placebo-controlled trials of fisetin (frailty, osteoarthritis, COVID recovery) are running or recently completed; the ones reported so far have been small and mixed. No senolytic has shown a change in disease outcomes or lifespan in people.
How to measure or use it
- There is no validated marker of senolytic effect in a routine blood panel. Trials use tissue biopsies and SASP cytokine panels.
- Dasatinib is a prescription chemotherapy agent with real side effects; fisetin and quercetin are supplements with poor oral bioavailability at the doses used in mice. None is something to run outside a trial or a physician's supervision.
- The evidenced way to lower senescent burden today is exercise, body-fat reduction and sleep — and the inflammation markers (hs-CRP) to track it.
Related
- The longevity drugs — senolytics alongside rapamycin and metformin
- Inflammation and immunity — what the SASP does
- Supplements that have evidence — where fisetin and quercetin rank
Frequently asked questions
Is fisetin a senolytic in humans?
It is in mice and in cell culture. Human trials are ongoing; the completed ones are small and have not shown clear senolytic effects at supplement doses.
How often are senolytics taken in trials?
Intermittently — typically two or three consecutive days, repeated every few weeks to months — because the goal is a periodic clearance, not steady exposure.
Should I take quercetin for senescence?
The evidence does not support it. Oral quercetin reaches low blood levels, and the senolytic effect in trials came from its combination with dasatinib.
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