Turkey Tail Mushroom: Benefits, Side Effects and the Cancer Question

Turkey tail benefits: what the research shows

Most research uses two purified extracts, PSK and PSP, rather than the powders sold as supplements.

Immune research

In lab and animal studies, PSK and PSP affect immune cells. In a US safety trial, 9 women who had finished breast cancer treatment took 3, 6 or 9g of turkey tail a day for 6 weeks, and researchers saw trends in some immune cell counts. These are early findings about blood markers, not proof that turkey tail prevents illness.

Gut health

In a 2014 randomised trial of 24 healthy volunteers, PSP changed gut bacteria over 8 weeks in a way consistent with a prebiotic (food for gut microbes). It measured bacteria, not symptoms. See gut health and supplements for digestion, or compare species in the functional mushrooms UK guide.

Turkey tail side effects and safety

Turkey tail is generally well tolerated in studies. Reported side effects:

• Digestive upset, such as bloating, gas or diarrhoea
• Dark stools, which Memorial Sloan Kettering (MSK) notes are not from bleeding
• Darkened fingernails (rare)
• Allergic reactions (rare)

iWhen PSK was given with chemotherapy, some patients had nausea, low white blood cell counts and liver problems, but it’s unclear whether the chemotherapy or PSK caused them. Stop and see a GP if you notice anything unusual.

Is turkey tail bad for your liver?

MSK’s monograph doesn’t list liver harm, and when we searched PubMed in October 2026 we found no published human case reports of liver injury from turkey tail. In a 2026 trial of 90 adults having a COVID-19 vaccine, a blend containing turkey tail caused no adverse events, and liver blood tests over 14 days showed no clear difference from placebo. Safety in liver disease hasn’t been studied, so ask your GP first.

Is turkey tail good for kidneys?

There’s no good evidence either way. We found no human studies of turkey tail and kidney health, and the main safety references don’t mention the kidneys. The 2026 vaccine trial saw no clear change in kidney blood tests, but it was short and in healthy adults. If you have kidney disease, check with your GP or renal team first.

Medicine interactions

The Natural Medicines database lists possible interactions with:

• Cyclophosphamide (a chemotherapy drug) and tamoxifen
• Diabetes medicines: turkey tail might lower blood sugar
• Medicines broken down by the CYP2C9 liver enzyme, which include warfarin (rated minor)

Who should avoid turkey tail?

• People having cancer treatment, unless their oncology team agrees
• People taking the medicines above, or immunosuppressants (such as after a transplant), unless a doctor or pharmacist agrees
• Pregnant or breastfeeding women, as there’s no safety data
• Anyone allergic to mushrooms or moulds

What is turkey tail?

Turkey tail is a thin, fan-shaped bracket fungus with bands of brown, tan and grey, like a turkey’s tail. It grows on dead wood across UK woodlands. Other names include Coriolus versicolor, yun zhi (Chinese) and kawaratake (Japanese). It’s too tough to eat, so it’s used as a tea or an extract.

PSK (krestin) was developed in Japan and PSP in China. UK supplements usually contain whole turkey tail powder or extract, not isolated PSK or PSP.

Turkey tail and cancer: what to know

According to the US National Cancer Institute, PSK has been used alongside standard cancer treatment in Japan since the mid-1970s. Pooled analyses of Japanese trials (8,009 people after gastric cancer surgery; 1,094 after colorectal cancer surgery) compared chemotherapy alone with chemotherapy plus PSK and reported better survival in the PSK groups. MSK notes that confirmatory studies are still needed and that results for other cancers are mixed.

This research is on a pharmaceutical extract given by cancer doctors, not on supplements. Turkey tail is not a cancer treatment and should never replace medical care. If you have cancer, talk to your oncology team before taking any supplement. Shiitake has a similar story: see shiitake and lentinan.

How much turkey tail should you take?

There’s no official UK dose. The US safety trial used 3 to 9g a day for 6 weeks. Product strengths vary, so follow the label and don’t combine several turkey tail products.

• Capsules or powders: the most common form. Check whether it’s fruiting body or mycelium grown on grain (which can be mostly starch), and look for stated beta-glucans and a batch lab test.
• Tea: simmer dried turkey tail for an hour or more; see how to make mushroom tea. It’s also in some mushroom coffees.
• Don’t forage unless you’re an expert: the look-alike “false turkey tail” (Stereum) is smooth underneath, not porous.

Avoid any product claiming to treat cancer or disease. See the best mushroom supplements in the UK for how to compare products.

Turkey tail vs reishi vs lion’s mane

For the evening, reishi is the traditional pick: see reishi for sleep, the best mushrooms for anxiety and lion’s mane vs reishi vs cordyceps.

Related guides: what really supports the immune system, cordyceps, mushrooms for inflammation, chaga mushroom (which has its own kidney warning), maitake and mushrooms for menopause.