Remedies › Turkey tail mushroom

Turkey tail mushroom (Trametes versicolor, PSK, PSP)

Also called Trametes versicolor, Coriolus versicolor, Yun Zhi, Yunzhi, Kawaratake, PSK, polysaccharide-K, Krestin, PSP, polysaccharopeptide, Papilocare.

Turkey tail is a striped bracket fungus that grows on dead wood. Three different things carry its name in the research. PSK (Krestin) was a standardised prescription drug extract, 3 g a day by mouth, used in Japan from the 1970s and no longer made. PSP is a related extract from China. Supplements sold as turkey tail vary and are rarely the products that were tested. Almost all the survival data below is PSK, not store capsules. Do not confuse it with Huaier (Trametes robiniophila), a different fungus sold in China with its own studies; those are not counted here.

What it has been studied for

Beyond Google: what a search won’t show you

Places a normal search rarely reaches: trial registries, a Tokyo Stock Exchange filing, NIH grant records and FDA adverse-event data. Each item links to its primary record.

Regulatory filing
The drug behind the headline numbers is no longer made
2017-03-17
Kureha told the Tokyo Stock Exchange it would stop making and selling Krestin fine granules, approved in 1976. Stated reason: difficulty procuring the materials needed to make it, and falling demand. Sales were due to end in September 2017, with the transition period due to end in March 2018. English pages still describe PSK as routinely prescribed in Japan. We read the notice through a search index copy of the PDF; it could not be opened directly.
Unpublished trial
The one blinded Papilocare trial finished in 2023; no result anywhere
Completed 2023-01-20
NCT04210336: a randomized double-blind trial in Spain (the registry lists triple masking) of 200 women, comparing the gel with a lactic acid gel, with cervical repair at 6 months as the main outcome. It is the kind of test the published studies lack. 45 months after it ended we found no results in PubMed, Europe PMC or the registry, which was last updated 2025-12-18.
Unpublished trial
Biopsy-proven CIN 1: the French randomized trial has no paper
Completed 2023-05-17
NCT04624568, run from the regional hospital in Orléans, randomized 81 women with biopsy-confirmed CIN 1 (single masked), with cytology normalization at 12 months as the main outcome. FIGO and reviewers complain that gel studies lack biopsy confirmation; this one had it. No matching paper in PubMed or Europe PMC.
Unpublished trial
A second high-risk HPV trial is also missing
Completed 2024-06-30
NCT04199078: open randomized trial of 164 women sponsored by Procare Health. No results in PubMed or Europe PMC beyond a mention in a general review of hydrogels. Three registered randomized gel trials together cover 445 women, about five times the 91 in the only published randomized paper.
Hidden contradiction
PALOMA: 91 women in the paper, 134 in the registry
2021 vs 2019
The published abstract (PMID 33746195) describes 91 women. The registry entry lists an actual enrollment of 134. It was also registered on 2019-06-21, more than three years after the trial began on 2015-10-19. The records do not explain the gap; analysis exclusions are one possibility we could not check. FIGO names retrospective registration as a concern.
Unpublished trial
The S-1 plus PSK gastric trial has no published result
Completed 2016-02
NCT00216034 (HKIT-GC) enrolled 255 people to test PSK with S-1 after stomach cancer surgery. The only paper we found (PMID 16803844) is the 2006 design report. No results in PubMed or Europe PMC. It would have tested PSK in stomach cancer with a newer oral drug than the older positive trials used.
Stalled trial
US PSK prostate trial withdrawn: "funding sequestered"
2013
NCT01685489 planned a double-blind phase 1b of PSK with docetaxel in metastatic prostate cancer at Bastyr University. It enrolled nobody. Registry reason, in full: funding sequestered. NIH RePORTER shows $380,350 for this project in 2012 (5U19AT006028-03).
Unpublished trial
Placebo-controlled Yunzhi breast cancer study, Barcelona
Estimated end 2010-12
NCT00647075 planned 60 adults at Hospital Clinic of Barcelona. Status is unknown and no publication was found.
Trial in progress
What to watch: Mayo, Hong Kong, Aarhus
2026
Mayo Clinic NCT06450873: 40 women with ER-positive, HER2-negative breast cancer take turkey tail before surgery, measuring Ki-67, due 2028. Chinese University of Hong Kong NCT05754801: 172 people with advanced cancer, Yunzhi essence vs placebo, quality of life, due 2027. Aarhus NCT07429071: 70 women, HPV clearance and CIN regression with the gel, a university-run trial. None has results.
FDA adverse events
7 CAERS reports name turkey tail, 2018 to 2023
Counted 2026-10-31
We recounted them individually, also searching coriolus, trametes, krestin and yunzhi. 3 hospital stays, 1 marked life-threatening, 0 deaths recorded. Reactions include jaundice in an 83-year-old and raised liver enzymes with yellow eyes in a 62-year-old, both taking other products; the second list includes ashwagandha and curcumin, which have their own liver reports. Only 1 report, for diarrhea, names turkey tail alone. These are reports, not findings: nobody established cause.
Trial results, registry only
Two US trials posted safety results for a two-mushroom product
2022
A Fomitopsis officinalis and Trametes versicolor product was tested double-blind in NCT04667247 (COVID-19 outpatients) and NCT04951336 (at COVID vaccination). Both have posted results: 0 serious adverse events (26 vs 24 and 52 vs 38 people at risk). Their primary outcomes were lab safety measures, so they say little about benefit.
Japanese journals
Two 2003 colorectal reports are not in PubMed
2003
Annals of Cancer Research and Therapy carried reports on oral adjuvant immunochemotherapy in Dukes C and Dukes B colorectal cancer (DOIs 10.4993/acrt1992.11.215 and .201). J-STAGE returned an error when we tried to open them, so we have not read them and do not count them.
Animal study
Dogs: the study behind many pet supplement claims
2012
People often ask about turkey tail for dogs. A double-blind pilot in dogs with hemangiosarcoma reported delayed spread and long survival with high-dose PSP (PMID 22988473). It is one pilot in dogs, the abstract gives no figures, and our scores cover human evidence only.

Sources searched on 2026-10-31: ClinicalTrials.gov (39 trials named turkey tail products or mushroom extracts, by our own search), NIH RePORTER, FDA CAERS (openFDA), Europe PMC preprints, Europe PMC patents, J-STAGE (Japanese journals), Tokyo Stock Exchange filings, EU Clinical Trials Information System (CTIS): 0 hits, ISRCTN registry: 2 gel pilots. Where we look

Safety notes

Doses up to 9 g a day of a turkey tail preparation were tolerated for 6 weeks in 9 women after breast cancer treatment: 9 adverse events, 7 mild, 1 moderate and 1 severe. That is a very small safety record for store-type products. Source
Cochrane could not tell whether side effects in the trials came from chemotherapy or from the extract itself. Source
In one early PSK study, the drug was stopped in 3 patients because of toxicity. The abstract does not describe it. Source
Interactions with chemotherapy are poorly studied. A systematic review found only two human pharmacokinetic studies, both of PSK with tegafur, showing no significant interaction. Most drugs have never been checked. Source
Tamoxifen: in rats, a PSP extract delayed the time to peak tamoxifen level (4.15 to 13.6 hours after one dose) without changing total exposure. There is no human study, and some oncology teams advise against combining them. Source
The phase 1 trial saw dose-related rises in B cells. Nobody has tested what that means for B-cell blood cancers such as CLL, so ask a hematologist first. Source
Vaginal gel: 7 possible or probable treatment-related adverse events in the PALOMA trial, most mild or moderate. Source
FDA food-safety reports (CAERS): 7 reports name turkey tail, 3 with hospital stays and 2 involving jaundice. In 6 of the 7 other products were also taken, and a report never proves cause. See Beyond Google.
Safety in pregnancy and breastfeeding was not studied in the human trials we read.

Possible links

Where one finding points to others. These are leads for research, not conclusions.

Other conditions

Immune function and vaccines 173 papers Mostly lab and animal work. Not yet read by us. See on PubMed
Gut microbiome 29 papers Includes a Beth Israel trial with posted results, NCT01414010. Not yet read by us. See on PubMed
Diabetes and blood sugar 12 papers Not yet read by us. See on PubMed
Memory and cognition 10 papers Not yet read by us. See on PubMed
Fatigue 8 papers Not yet read by us. See on PubMed
Hepatitis and liver disease 8 papers Not yet read by us. See on PubMed
COVID-19 6 papers Two small US trials of a two-mushroom product; see Beyond Google. See on PubMed

Same mechanism

TLR2 activation 6 papers PSK switches on the immune receptor TLR2 in lab studies, through a lipid in the extract rather than its glucan. Hot-water extracts were more potent than ground mushroom. See on PubMed Source
Beta-glucans via Dectin-1 28 papers The soluble beta-glucan enters immune cells through the Dectin-1 receptor; the same paper finds the lipid and the glucan work together. See on PubMed Source

Combinations

Turkey tail with chemotherapy 461 papers The main setting; see the cancer page. See on PubMed
Turkey tail with radiotherapy 76 papers Mostly small and old. See on PubMed
Turkey tail with immune checkpoint drugs 11 papers Early; no human trial read by us. See on PubMed

Who does the research

K. Matsunaga 40 papers Biomedical Research Laboratories, Kureha Chemical Industry, Tokyo: the company that made Krestin.
K. Nomoto 31 papers As given by PubMed; no affiliation on the record we used.
T. Fujii 29 papers Kureha Biomedical Research Laboratories, Tokyo.
H. Nakazato 17 papers Yokoyama Gastrointestinal Hospital, Japan; lead of the Lancet gastric trial group.
T. Jędrzejewski 13 papers Department of Immunology, Nicolaus Copernicus University, Poland; recent lab work.

Who pays for it

US NIH: NCCIH 14 papers
US NIH: National Cancer Institute 11 papers
National Natural Science Foundation of China 5 papers
Narodowe Centrum Nauki (Poland) 2 papers
Elpen Pharmaceutical (Greece), which sponsored the Greek gel study 1 papers

Counts are papers in our three PubMed lists (935 unique records) where PubMed records a funder; most list none, and almost none of the older Japanese trials do. Author affiliations show that Kureha staff wrote many early papers. The Papilocare trials are sponsored by Procare Health according to their registry entries.

What people report

We read public first-person posts and counted every outcome, good or bad. 21 reports, read on 2026-10-31; 4 mention side effects.

10Helped
4No effect
2Got worse
2Mixed
3Too early

Why these counts prove nothing on their own: people who post are not a random sample, most take other treatments at the same time, and nobody checks the diagnosis. We show them because they tell researchers what to test next.

Read all 21 reports

No effect Took turkey tail about five months and Papilocare; still HPV positive after six months, no side effects. Inspire, 2021-05-11 (Home test only; many supplements together.)
Mixed CIN 1 cleared but still HPV positive; stopped because hives became too much. Side effects: hives. Inspire, 2021-05-10 (The original post was not readable, so which supplement caused the hives is unclear; poster doubts it explains the result.)
No effect Used Papilocare for months and says it did not help; in an earlier thread credits AHCC more for HPV 16 going dormant. Inspire, 2020-05-31 (Two posts by one person counted once.)
Worse Papilocare caused irritation and did not help; later cleared HPV after switching to a different gel. Side effects: irritation. Inspire, 2023-11-22 (A later product does not show why it cleared.)
Helped Normal Pap and negative HPV test after six months on a long supplement list. Side effects: hives from a separate topical treatment. Inspire, 2018-06-26 (Eight treatments at once, and the poster notes CIN 2 often clears by itself.)
Worse After five days of reishi and turkey tail, nearly fainted with headaches and fatigue; suspects reishi. Side effects: near-fainting, severe headaches, fatigue. Inspire, 2018-05-04 (Two mushrooms; no diagnosis of a reaction.)
Helped Took turkey tail powder daily and calls it great for HPV. Inspire, 2014-02-26 (No test result given.)
No effect Nearly six years on Ibrance with daily turkey tail; reports no problems and claims no benefit. Inspire, 2022-08-07 (Tolerance report, recorded as no effect.)
Helped Takes turkey tail regularly; liver lesions slightly smaller on the last scan. Inspire, 2022-08-07 (Other treatment likely; one scan.)
Helped Clear scan after four months and further clear scans; credits mushrooms, though letrozole started the same day. Inspire, 2023-12-04 (Letrozole is a proven treatment started at the same time.)
Helped Neutrophils stay in low normal range and infections became far fewer; great quality-of-life gain. Inspire, 2022-08-09 (Personal attribution.)
Helped Says turkey tail seems to help, used as a complement under supervision. Inspire, 2022-08-09 (Vague outcome.)
Mixed Close to ten years on mushroom extracts; blood tests normal, tumor markers move around. Inspire, 2022-08-09 (No claim of cause.)
Helped Started mushrooms after last chemotherapy; reports four clear PET scans since. Inspire, 2024-02-09 (Chemotherapy came first; post names a product, and turkey tail content is not confirmed.)
Helped White cell count rose to above the minimum after first using turkey tail powder. Inspire, 2024-02-11 (Single blood result.)
Too early Taking turkey tail alongside reduced tamoxifen on own initiative; no result yet. Mayo Clinic Connect, 2025-04-02 (Another member later warned of a tamoxifen interaction.)
Too early Six months on tamoxifen with a daily supplement; few side effects, no outcome reported. Mayo Clinic Connect, 2023-11-29 (Tolerance only.)
Too early Started a few months ago and will continue turkey tail; no outcome reported. Mayo Clinic Connect, 2025-10-13 (No outcome.)
No effect Took mushroom supplements during radiation with no problems; says there was no comparison. HealthUnlocked (Date shown only as about four years ago.)
Helped Takes turkey tail for low white cells, which rose, and says it helps fatigue. Inspire (Read from the search result text; thread not opened.)
Helped Reports a cancer center put them on turkey tail; says it helps with cold sores. HealthUnlocked (Read from the search result text; thread not opened.)

Checked against PubMed on 2026-10-31.