Saxe G., Shubov A., Smith C.N., Golshan S., Shekhtman T., Wilson S., Slater D., Bair Z.J., Beathard C., Davis R.A., MacElhern L., Kao L.K., Senowitz P., Gosnell N., Buchholz D., Aguilar-Carreno H. Polypore mushroom mycelia for treatment of active COVID-19 infection: A randomized clinical trial. medRxiv. 2026.06.01.26354267.
Rationale
Mushroom mycelium shows antiviral properties in vitro and represents a potentially new strategy against existing and emerging viral infections. The authors hypothesized that the FoTv mycelial blend (Fomitopsis officinalis + Trametes versicolor) could be safe, tolerable, and able to reduce COVID-19 symptom severity — and possibly act directly against the virus.
Methods
Design — a randomized double-blind placebo-controlled RCT at two centers (UCSD and UCLA). Population — non-hospitalized adults with mild-to-moderate COVID-19, confirmed within ≤96 hours, symptom duration ≤9 days at enrollment. Intervention — FoTv (Fomitopsis officinalis + Trametes versicolor mycelial blend) or placebo; 50 patients randomized (26 FoTv, 24 placebo). Primary aims were safety and feasibility; secondarily, number and severity of COVID-19 symptoms (emphasis on sore throat and cough) plus an in-vitro antiviral assessment in a SARS-CoV-2 pseudovirus model.
Results
FoTv was safe, well tolerated and practically feasible for COVID-19 treatment. Only minor between-group differences in biochemical markers were seen (26 FoTv vs 24 placebo). FoTv significantly reduced the number and severity of symptoms — particularly sore throat and cough. In a parallel in-vitro series, FoTv reduced pseudovirus cell infection. The abstract does not give effect sizes, confidence intervals or exact p-values for individual symptoms.
Conclusions
The authors conclude that FoTv is safe, reduces COVID-19 symptoms, and reduces cellular viral infection — and that future studies should examine the therapeutic benefit of mushroom mycelium against SARS-CoV-2 and other viruses.
Identifiers & funding
- Registration: ClinicalTrials.gov NCT04667247.
- DOI: 10.64898/2026.06.01.26354267.
- Source: medRxiv preprint (not peer-reviewed).
- Funding: Krupp Endowed Fund, Jonathan and Kathleen Altman Foundation, Fungi Perfecti LLC, Sacharuna Foundation, Jesy Foundation, Texas Instruments Foundation. Three co-authors (Z.J. Bair, C. Beathard, R.A. Davis) are employees of Fungi Perfecti — the commercial manufacturer of FoTv.
Worth noting
Above all: this is a medRxiv preprint — not yet peer-reviewed, so its conclusions carry less weight than a reviewed article. The sample is small (n=50), and inclusion was limited to non-hospitalized mild-to-moderate cases ≤9 days from symptom onset — nothing can be said about severe COVID-19, hospitalization or mortality. The antiviral effect was shown only in an in-vitro pseudovirus model, not in patients (viral load is not reported in the abstract). Some authors are employees of Fungi Perfecti, the manufacturer — caution applies, especially for self-reported symptom scales. Finally, the material is a specific manufacturer's dried mycelium, not a standardized fruiting-body extract; extrapolation to other products is improper.