Fisetin is a flavonol, a plant pigment found in small amounts in fruits such as strawberries. It is sold as a dietary supplement.
Fisetin has no intake value or upper limit. The only human pharmacokinetic study we found used a single 1,000 mg dose of plain fisetin and of an encapsulated formulation (Krishnakumar 2022). That is a study protocol, not a recommendation.
It is sold in the US as a dietary supplement. Under the 1994 dietary supplement law (DSHEA), FDA does not approve dietary supplements before they are marketed, and the maker, not FDA, is responsible for safety and labeling. There is no FDA-approved fisetin drug.
The authors of the one human pharmacokinetic study (Krishnakumar 2022, 15 healthy adults, funded by a supplement maker) describe it as the first of its kind. Plain fisetin reached low blood levels and was not detectable after 2 hours; no adverse events were reported. Evidence in people beyond that is limited.
In the only human pharmacokinetic study we found (Krishnakumar 2022), plain fisetin (1,000 mg) peaked about 0.9 hours after a dose with a half-life of about 1.1 hours; an encapsulated form peaked at about 1.2 hours with a half-life of about 1.5 hours. Dose Track uses the plain-fisetin figures: a 1.1-hour half-life and a 1-hour peak.
Numbers shown are the values Dose Track uses, listed only where they agree with the source above. Half-life varies from person to person and with injection site.