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Key takeaways
• The Mayo Clinic pulsed protocol is 20 mg/kg per day for two consecutive days, then 28 days off — approximately 12 pulses per year (3,4).
• Every published human fisetin senolytic trial uses this protocol or a close variant — AFFIRM, COVID-FIS, COVFIS-HOME, the OA cartilage trial, PROFFi, and Fisetin HIGH (3,4,5,6,7,8).
• The rationale is the hit-and-run principle — senescent cells regenerate slowly, so a brief pulse briefly pushes fisetin above the senolytic threshold and then falls away (1,2).
• For a 70 kg adult, the protocol is approximately 1,400 mg on day 1 and 1,400 mg on day 2, taken with fatty meals. Then no fisetin for four weeks.
• No published human trial has yet reported that this protocol produces senolytic effects in humans — the biology is a strong hypothesis; the clinical proof is pending (13,14).
• The pulsed protocol is not a treatment. It is a translational hypothesis being tested in six ongoing trials.
Quick answer
The Mayo Clinic pulsed fisetin protocol is 20 mg/kg per day for two consecutive days, then 28 days off — a monthly cycle, approximately 12 pulses per year. For a 70 kg adult this is roughly 1,400 mg on day 1, 1,400 mg on day 2, then no fisetin for four weeks. This is the schedule every ongoing human trial uses. The biological rationale is that senescent cells resist apoptosis via specific anti-apoptotic pathways, and a brief high-concentration pulse of fisetin briefly interferes with those pathways enough to trigger apoptosis without persistent off-target exposure. This article walks through the rationale, the schedule, and the honest evidence caveat: as of 2026, no peer-reviewed randomised trial has yet confirmed that the protocol works in humans.
Where the protocol came from
The pulsed dosing pattern for fisetin was designed by the Mayo Clinic translational geroscience group, principally James Kirkland and Tamar Tchkonia, who developed the founding senolytic combination of dasatinib plus quercetin (D+Q). Their D+Q protocol used three consecutive days of oral dosing per month — a hit-and-run pattern intended to briefly clear senescent cells and then let tissue recover (2,12). When fisetin was identified as the most potent natural senolytic in the 2018 Yousefzadeh screen, the same protocol architecture was carried over: consecutive high-dose days followed by a long off-cycle (1).
The specific choice of two days at 20 mg/kg reflects three considerations. First, mouse-to-human dose conversion — the 100 mg/kg mouse gavage dose used in Yousefzadeh 2018 corresponds to roughly 8 mg/kg human by strict body-surface-area conversion; the 20 mg/kg trial dose sits above this to provide margin against the flavonoid bioavailability ceiling. Second, two consecutive days doubles the tissue exposure time above the senolytic threshold without pushing single-day dosing into the diminishing-return region of oral absorption (10). Third, once-monthly cycling matches the observed timeline of senescent-cell regeneration in mouse tissue — the population takes weeks to rebuild after clearance.
The hit-and-run principle
This is the single biological concept that unifies the entire senolytic pharmacology, and understanding it explains why daily fisetin dosing is not senolytic dosing.
Senescent cells are hard to kill
Cells that enter senescence upregulate a battery of pro-survival proteins — collectively called SCAPs, senescent cell anti-apoptotic pathways — that make them resistant to programmed cell death. BCL-2 and BCL-xL prevent mitochondrial permeabilisation. PI3K/AKT signalling maintains cellular metabolism. HIF-1α protects against hypoxic stress. Multiple tyrosine kinases sustain survival signalling. Together these pathways create redundant resistance to apoptosis, which is why simple antioxidant or anti-inflammatory approaches do not clear senescent cells (2).
Fisetin interferes with several SCAPs simultaneously
The Mayo Clinic mechanistic work — first Zhu 2017, then Yousefzadeh 2018 — established that fisetin has activity against multiple SCAPs at once (1). It has documented activity at BCL-xL, PI3K/AKT, and several kinases. This promiscuous mechanism means fisetin can push senescent cells past their apoptotic threshold where a single-target drug might not.
Peak concentration matters more than sustained concentration
Because SCAPs are redundant, tipping a senescent cell into apoptosis requires briefly exceeding a threshold of pathway interference. Above the threshold, apoptosis proceeds. Below it, the cell survives even with substantial pathway inhibition. This is fundamentally different from a sustained-target drug — statins, for instance, provide continuous HMG-CoA reductase inhibition to keep cholesterol synthesis suppressed. Senolytics are more like a brief chemical push than a sustained pharmacological hold.
Once cleared, senescent cells stay cleared
After a pulse, the senescent-cell population takes weeks to rebuild in mouse tissue. Continuous senolytic exposure is therefore not necessary — the biology does not require it. Continuous exposure may even be counterproductive: it risks off-target effects on healthy cells (particularly above the senolytic window), and it may down-regulate the responsiveness of any residual senescent cells to future pharmacological pressure.
Put together, these four principles produce the hit-and-run protocol: brief, high-peak pulses of senolytic drug, followed by long off-periods during which no senolytic exposure occurs. This is the founding architecture for both D+Q and fisetin trials.
The practical schedule — a month at a time
Below is the protocol translated into a monthly schedule for typical adult body weights.
|
Body weight |
Day 1 dose |
Day 2 dose |
Days 3–28 |
|
50 kg (110 lb) |
1,000 mg with fat |
1,000 mg with fat |
No fisetin |
|
60 kg (132 lb) |
1,200 mg with fat |
1,200 mg with fat |
No fisetin |
|
70 kg (154 lb) |
1,400 mg with fat |
1,400 mg with fat |
No fisetin |
|
80 kg (176 lb) |
1,600 mg with fat |
1,600 mg with fat |
No fisetin |
|
90 kg (198 lb) |
1,800 mg with fat |
1,800 mg with fat |
No fisetin |
|
100 kg (220 lb) |
2,000 mg with fat |
2,000 mg with fat |
No fisetin |
Cycle monthly. The most straightforward way to remember the schedule is to place the two pulse days on a fixed calendar date each month — for example, the first weekend of each month, or the 1st and 2nd of every month. Missing a pulse is not catastrophic; the effect over years is small. Do not double up if you miss a pulse — simply resume at the next scheduled cycle.
Practical translation to a commercial capsule
If your commercial fisetin product is 500 mg per capsule, the trial-aligned pulse for a 70 kg adult is approximately 3 capsules on day 1 and 3 capsules on day 2 — total 6 capsules per month rather than 30. This uses the same product in a different pattern. Take the day’s dose as a single amount with a fat-containing meal, not split across the day.
If your product is 100 mg per capsule, the same 70 kg-adult protocol is 14 capsules on day 1 and 14 on day 2 — practically inconvenient but technically consistent with the trial protocol. Higher-strength capsules are more practical for pulsed dosing; lower-strength capsules are more suited to continuous daily formats. Our dedicated dosage article walks through the numbers in detail.
What the ongoing trials are testing
Six trials use this protocol architecture. Each tests a different clinical indication.
|
Trial (NCT) |
Population |
Primary endpoint |
|
AFFIRM (NCT03430037) (3) |
Post-menopausal frail women |
Adipose senescent-cell burden, physical function |
|
COVID-FIS (NCT04537299) (4) |
Nursing home residents with COVID |
Mortality, functional decline |
|
COVFIS-HOME (NCT04771611) (5) |
Community-dwelling adults with COVID |
Symptom resolution, inflammatory markers |
|
OA Cartilage (NCT04210986) (6) |
Adults with knee osteoarthritis |
Cartilage integrity, joint symptoms |
|
PROFFi (NCT06113016) (7) |
Breast cancer survivors |
Frailty prevention, muscle function |
|
Fisetin HIGH (NCT06431932) (8) |
Healthy volunteers + multimorbid older adults |
Pharmacokinetics, safety, tolerability |
The trials share dosing architecture but test different endpoints. AFFIRM is the load-bearing readout — Phase 2, double-blind, placebo-controlled, with adipose senescent-cell burden and physical function as the primary endpoints. It has been recruiting since 2018 and remains unreported (3). When it publishes, this article and the entire cluster will be revised. See our dedicated senolytic article for the trial-pipeline context.
Why not daily dosing? A tissue-concentration perspective
The most common reader question about the pulsed protocol is: why not just take a smaller amount every day? Wouldn’t that be more convenient and provide continuous exposure? The answer sits at the intersection of pharmacokinetics and senescent-cell biology.
Fisetin has a short plasma half-life (approximately two hours in the Krishnakumar 2022 study) and does not accumulate meaningfully over 24-hour dosing intervals (10). A 500 mg daily dose produces a modest morning plasma peak followed by rapid clearance; by evening, plasma fisetin is essentially undetectable. Repeating this pattern daily maintains a low average plasma concentration but never approaches the senolytic threshold in tissue. It is not that daily dosing produces a small senolytic effect — it produces essentially no senolytic effect, because the concentration ceiling is set by absorption per dose, not by cumulative exposure.
The pulsed protocol addresses this by concentrating the entire monthly dose into a brief two-day window. This produces the highest plasma peak achievable from unformulated fisetin, briefly pushes tissue concentration into the senolytic window, and clears senescent cells. The remaining 28 days serve as an off-period during which the tissue recovers and any residual off-target effects dissipate. Our dedicated bioavailability article walks through the pharmacokinetic detail.
The 2025 Murray paper — mouse validation of the pulsed approach
Murray and colleagues (Aging Cell, 2025) is the most recent and most consequential preclinical validation of intermittent fisetin dosing (11). Twenty-four-month-old mice were given intermittent fisetin at doses equivalent to the human 20 mg/kg pulsed protocol, and compared against vehicle control, INK-ATTAC genetic clearance of p16-positive cells, and ABT-263 (a pharmaceutical BCL-xL inhibitor). Fisetin preserved grip strength, gait speed, and muscle fibre integrity, with effect sizes statistically indistinguishable from the two comparators. This is head-to-head equivalence between a natural flavonoid and gold-standard preclinical senolytic interventions.
The Murray paper does not close the human translational gap — it is a mouse study — but it is the strongest recent preclinical evidence that intermittent fisetin at the mouse-equivalent of the human trial dose produces senolytic effects. When AFFIRM and PROFFi publish, we will find out if humans respond similarly.
Safety of the pulsed protocol
The Mayo Clinic pulsed protocol has been generally well tolerated across the trials that have completed enrolment. No serious adverse events specifically attributable to fisetin have been reported in the trial publications and registry entries to date (9). The COVID-FIS trial completed in November 2024 with a favourable safety profile in nursing home residents — a population unusually vulnerable to adverse drug effects.
This safety record applies specifically to the pulsed protocol. Continuous daily high-dose fisetin (multiple grams per day, taken indefinitely) has not been formally characterised for long-term human safety and should not be self-administered. The pulsed protocol’s 28-day off-cycle limits total annual exposure and gives the body time to metabolise and clear residuals — an important safety feature of the trial architecture.
What we still don’t know
• Whether the 20 mg/kg × 2 days protocol actually produces senolytic effects in humans. This is the central unanswered question. AFFIRM and Fisetin HIGH will begin to answer it.
• Whether a different pulse schedule would work better. Weekly pulses? Bi-monthly pulses? Longer pulses? Higher doses? No published trial has compared alternative schedules.
• How long the senolytic effect persists after each pulse. Mouse data suggest weeks to months; human durability is unmeasured.
• Whether cumulative benefit accrues over years or hits a ceiling as resistant senescent-cell subpopulations expand. This is a multi-year question.
• How pulsed fisetin interacts with concurrent medications, particularly chronic anti-inflammatory or antiplatelet therapy. No formal interaction studies exist.
• Whether specific patient populations respond differently. All trials use the same dose regardless of body composition, sex, age, or baseline frailty.
Bottom line
The Mayo Clinic pulsed protocol — 20 mg/kg for two consecutive days, then 28 days off, cycled monthly — is the single dosing pattern used in every published human trial of fisetin as a senolytic. Its biological rationale (the hit-and-run mechanism of senescent-cell clearance) is coherent. Its preclinical validation (Murray 2025) is strong. Its clinical validation is pending — the AFFIRM readout, when it arrives, will be the most consequential publication in the fisetin field. Readers who want to align with the trial evidence should follow this protocol. Readers who prefer continuous daily flavonoid supplementation are taking a different, defensible approach that is not a senolytic protocol as tested. See our complete clinician’s guide for full context.
Frequently asked questions
What is the Mayo Clinic fisetin protocol?
Twenty milligrams per kilogram body weight per day, for two consecutive days, cycled every 28 days. For a 70 kg adult: approximately 1,400 mg on day 1, 1,400 mg on day 2, then no fisetin for four weeks.
How often should I do a pulse?
Every 28 days is the trial protocol. Approximately 12 pulses per year. More frequent pulsing is not evidence-based and may erode the biological rationale of the hit-and-run approach.
Is the pulse dose safe?
The pulsed protocol has been well tolerated in Mayo Clinic trials to date (9). No serious adverse events specifically attributable to fisetin have been reported. Continuous daily high-dose fisetin has not been characterised for long-term safety.
Do I need to fast before a pulse?
No. Take the pulse with a fat-containing meal — fasted administration produces very low plasma fisetin levels (10). Fatty breakfast with the day’s dose taken in a single sitting is the practical trial-aligned pattern.
What is the Bryan Johnson / David Sinclair fisetin protocol?
Publicly documented longevity practitioners including Bryan Johnson and David Sinclair have reported using variations of the pulsed protocol — high-dose fisetin for two consecutive days on a monthly cycle, with 28 days off. This mirrors the Mayo Clinic trial dose. Neither practitioner’s specific regimen has been formally studied, but both align with the trial-validated architecture.
Can I combine fisetin pulses with dasatinib plus quercetin pulses?
This combination is not tested. Dasatinib is a prescription drug and should only be used under medical supervision. The theoretical rationale for combining senolytics with different SCAP targets exists, but the interaction has not been characterised in humans.
When will the AFFIRM trial publish?
Unknown. AFFIRM has been recruiting since 2018 and is the longest-overdue readout in the geroscience literature. The manuscript was expected years ago and has not yet appeared.
References
1. Yousefzadeh MJ, Zhu Y, McGowan SJ, et al. Fisetin is a senotherapeutic that extends health and lifespan. EBioMedicine. 2018;36:18-28. https://pmc.ncbi.nlm.nih.gov/articles/PMC6197652/
2. Xu M, Pirtskhalava T, Farr JN, et al. Senolytics improve physical function and increase lifespan in old age. Nat Med. 2018;24(8):1246-1256. https://pubmed.ncbi.nlm.nih.gov/29988130/
3. AFFIRM: Alleviation by Fisetin of Frailty, Inflammation, and Related Measures in Older Women (NCT03430037). ClinicalTrials.gov. https://clinicaltrials.gov/study/NCT03430037
4. COVID-FIS: Phase 2 Placebo-Controlled Pilot Study of Fisetin in Older Adults in Nursing Homes (NCT04537299). ClinicalTrials.gov. https://clinicaltrials.gov/study/NCT04537299
5. COVFIS-HOME: Home-Based Study of Fisetin in Community-Dwelling Adults With COVID-19 (NCT04771611). ClinicalTrials.gov. https://clinicaltrials.gov/study/NCT04771611
6. A Trial of Fisetin to Treat Cartilage Degeneration in Osteoarthritis (NCT04210986). ClinicalTrials.gov. https://clinicaltrials.gov/study/NCT04210986
7. PROFFi: Prevention of Frailty with Fisetin and Exercise in Breast Cancer Survivors (NCT06113016). ClinicalTrials.gov. https://clinicaltrials.gov/study/NCT06113016
8. Pilot Trial of Fisetin in Healthy Volunteers and Older Patients with Multimorbidity — Fisetin HIGH (NCT06431932). ClinicalTrials.gov. https://clinicaltrials.gov/study/NCT06431932
9. Verdoorn BP, Evans TK, Hanson GJ, et al. Fisetin for COVID-19 in skilled nursing facilities: senolytic trials in the COVID era. J Am Geriatr Soc. 2021;69(11):3023-3033. https://pmc.ncbi.nlm.nih.gov/articles/PMC8447437/
10. Krishnakumar IM, Jaja-Chimedza A, Joseph A, et al. Enhanced bioavailability and pharmacokinetics of a novel hybrid-hydrogel formulation of fisetin orally administered in healthy individuals. J Nutr Sci. 2022;11:e74. https://doi.org/10.1017/jns.2022.72
11. Murray KO, Mahoney SA, Venturini S, et al. Intermittent supplementation with fisetin improves physical function and decreases cellular senescence in skeletal muscle with aging. Aging Cell. 2025;24:e70114. https://doi.org/10.1111/acel.70114
12. Justice JN, Nambiar AM, Tchkonia T, et al. Senolytics in idiopathic pulmonary fibrosis: results from a first-in-human, open-label, pilot study. EBioMedicine. 2019;40:554-563. https://pubmed.ncbi.nlm.nih.gov/30616998/
13. Khosla S. Translating senolytics from mice to humans. GeroScience. 2025. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12759346/
14. Niedernhofer LJ, Robbins PD. Fisetin as a senotherapeutic agent: evidence and perspectives for age-related diseases. Mech Ageing Dev. 2024;220:111995. https://doi.org/10.1016/j.mad.2024.111995