Reishi mushroom: what the evidence says, including in cancer care

Reishi (lingzhi in Chinese) is a hard, shiny, woody fungus that grows on trees. It is too tough and bitter to eat as a vegetable, so it is traditionally simmered into a tea or decoction, and today it is mostly sold as powders, extracts and capsules. The National Cancer Institute notes that its chemistry centers on triterpenoids and polysaccharides, that many products are mixtures from different extraction methods, and that products grown on grain can contain large amounts of alpha-glucans from the grain substrate rather than the mushroom itselfNIH. Two products sold under the same name may therefore be quite different.

In some places, such as Shanghai, people with cancer commonly take reishi supplements NIH. The 2016 Cochrane review found five randomized trials. Their methods were generally unsatisfactory and reported inadequately. When reishi was given alongside chemotherapy or radiotherapy, more people had a measurable tumor response than with conventional treatment alone; reishi on its own did not show the same response. No trial measured long-term survival Jin 2016.

The reviewers concluded there was not enough evidence to justify reishi as a first-line cancer treatment, that it remains uncertain whether it helps people live longer, and that it could be considered as an add-on to conventional treatment after weighing cost and preference Jin 2016. In its section on lung cancer, the NCI summary states that there are no studies of reishi with measured cancer outcomes, and describes a 12-week open-label study of a reishi polysaccharide product in advanced lung cancer that did not change average immune measures NIH.

A Cochrane review of reishi for cardiovascular risk factors found five trials with 398 participants. The three that could be analyzed all enrolled people with type 2 diabetes and compared 1.4 to 3 grams a day with placebo for 12 to 16 weeks. Reishi did not meaningfully lower HbA1c, total or LDL cholesterol, blood pressure or BMI, and people taking it for four months were somewhat more likely to report side effects, none seriousKlupp 2015. The authors concluded the evidence does not support it for these risk factors.

If you want to try reishi as a traditional tea, sliced dried mushroom is the old form. Online, iHerb lists reishi teas and powders; look for products that say what part of the mushroom they contain, and keep the safety notes below in mind.

Case reports link reishi powder to liver injury. A patient in Hong Kong developed hepatotoxicity from a reishi formulation in 2004 Yuen 2004, and a Thai report described fatal fulminant hepatitis in a patient who had switched from traditionally boiled reishi to powder for one to two months; both patients were also taking other medicines Wanmuang 2007. A 2023 US report described acute hepatitis in a man who took reishi powder with alcohol; it resolved with treatment Guedikian 2023. Case reports cannot show how often this happens, but they are why liver symptoms (dark urine, yellowing skin or eyes, pain under the right ribs) mean stop and get checked.

Lab studies once suggested reishi might slow blood clotting. When researchers tested it in 40 healthy volunteers, 1.5 grams a day for four weeks caused no change in clotting or platelet tests compared with placeboKwok 2005. That is reassuring for healthy people at that dose, but it did not test higher doses or people taking blood thinners, so mention reishi before surgery or if you take anticoagulants.