Reishi

What it is

What is sold as reishi is usually Ganoderma lucidum; the Chinese lingzhi is sometimes classified botanically as a separate species, Ganoderma lingzhi. The dried fruiting body, extracts made from it and the spores are used. The most important constituents are polysaccharides, including beta-glucans from the cell wall, and triterpenoids, plus nucleosides.

In traditional Chinese medicine, reishi is used to promote health, restore vitality and prevent disease; in marketing it is often called the mushroom of immortality. Today it is advertised mainly for the immune system, stress, sleep and liver protection.

How it is supposed to work

The polysaccharides are supposed to stimulate immune cells, and the triterpenoids to dampen inflammation and protect the liver. These mechanisms come predominantly from laboratory research and animal experiments. What has been measured in humans is mainly immune cell counts in the blood, questionnaires on fatigue and quality of life, and metabolic values.

An example of how far apart laboratory and human results can be: test-tube experiments suggested that reishi inhibits blood platelets. In a double-blind trial with 40 healthy volunteers, however, none of the measured clotting values changed over 4 weeks.

What the studies show

Tang 2005, neurasthenia

Multicenter, double-blind, placebo-controlled trial with 132 patients, 8 weeks, 123 of them evaluable. Severity and fatigue decreased more with reishi than with placebo, fatigue by 28.3 versus 20.1 percent. 51.6 versus 24.6 percent improved more than minimally. The extract was well tolerated.

Cochrane 2016, supportive cancer care

5 randomized trials, methodologically unsatisfactory in the authors’ judgment. Tumor response in combination with chemotherapy or radiotherapy was more favorable with a risk ratio of 1.50, but the confidence interval of 0.90 to 2.51 also includes no effect. No trial recorded long-term survival. Conclusion: not a first-line therapy, at most worth considering as an add-on.

Cochrane 2015 and RCT 2016, cardiovascular

5 trials with 398 participants on blood sugar, blood pressure and blood lipids, plus the authors’ own double-blind trial with 84 people with type 2 diabetes over 16 weeks. No effect on HbA1c, fasting glucose, cholesterol, blood pressure or triglycerides. The authors see no basis for using reishi to treat these risk factors.

Kwok 2005, blood clotting

Double-blind trial with 40 healthy volunteers, 20 each with reishi or placebo over 4 weeks. Measurements included a coagulation screen, fibrinogen, von Willebrand factor, platelet function and thromboelastography, before intake and after 4 and 8 weeks. There was no difference between the groups; all values remained within the normal range. People on anticoagulants were not included.

Li 2007, rheumatoid arthritis

65 patients with active rheumatoid arthritis received reishi with a traditional herbal mixture or placebo for 24 weeks in addition to their therapy. The primary endpoint, a 20 percent improvement according to the American College of Rheumatology criteria, was reached by 15 versus 9.1 percent; the difference was not significant. Pain and patient assessment improved only in the reishi group; inflammation and immune values remained unchanged.

Meta-analysis Jafari 2025

17 randomized trials with 971 participants over 1 to 24 weeks. Small effects on body mass index, creatinine and heart rate, none on inflammation markers, liver enzymes, blood lipids or blood sugar. The authors rate the quality of evidence as very low for all endpoints.

Where the data stop

For sleep, one of the most heavily advertised effects, we found no human study, only experiments in mice. In the patient survey, insomnia even appeared as a side effect. An anti-inflammatory effect has not been demonstrated in humans either: the meta-analysis found no effect on inflammation markers, and in a trial with 65 rheumatism patients over 24 weeks, pain and patient assessment did improve, but measurable anti-inflammatory effects did not materialize. Human studies on liver protection are lacking; the meta-analysis saw no effect on liver enzymes.

For cancer, the Cochrane review sees insufficient evidence; an effect on survival has not been studied. In 2015, the joint expert commission of BVL and BfArM stated that advertising claims about cancer, aging, rheumatism or depression for medicinal mushrooms such as reishi lack a scientific basis. Most studies are small, short and use different preparations, from fruiting body powder to spores and extracts.

Status, approval and legal

According to the assessment of a joint expert commission of BVL and BfArM from 2015, products made from Ganoderma lucidum, as well as from Cordyceps sinensis and Coriolus versicolor, are to be regarded not as foods but as medicines. Reishi is not approved as a medicine in Germany. According to the Verbraucherzentrale (German consumer advice centre), the fruiting bodies have been used as dietary supplements in the EU for more than 20 years. Because it is not an approved active substance, this page gives no dosage. No relevance to doping is noted in the sources checked.

Safety

In the studies, reishi was mostly well tolerated; in the survey of the 1,374 cancer patients, 9.1 percent reported side effects, most often dry mouth, constipation, insomnia, itching and dizziness. The US database LiverTox classifies reishi as a possible rare cause of liver injury; individual cases have been described, including one fatal case, mostly after 1 to 6 months of intake. A case report describes acute hepatitis after reishi powder taken together with alcohol. According to the Verbraucherzentrale, reishi can lead to dangerous hypoglycemia, even in people without diabetes; caution is therefore advised with diabetes medication. Beta-glucan extracts from mushrooms should not be taken together with cortisone or anti-inflammatory painkillers. A study in healthy people found no effect on blood clotting, but reishi has not been studied in people taking anticoagulants; this should be clarified with a doctor beforehand. There are no data for pregnant and breastfeeding women.

Sources

• Jin et al., Cochrane Database Syst Rev 2016 (CD007731)
• Klupp et al., Cochrane Database Syst Rev 2015 (CD007259)
• Klupp et al., Sci Rep 2016
• Tang et al., J Med Food 2005
• Jafari et al., Food Sci Nutr 2025
• Kwok et al., Anesth Analg 2005
• Li et al., Integr Med Res 2024
• LiverTox, Lingzhi (Reishi), NIDDK
• BVL, Medicinal mushrooms – food or medicine?, 2015
• Verbraucherzentrale (German consumer advice centre), Medicinal mushrooms for cancer therapy?, 2025