Reishi Mushroom: What the Research Really Says (2026 Guide)
Reishi is one of the most famous mushrooms in traditional Chinese medicine, where it’s known as lingzhi. It has been called the “mushroom of immortality”, and today it’s sold as dried slices, powders, teas and “mushroom coffee”. But what does modern research actually show? This guide looks at what reishi is, what two Cochrane reviews found, and the safety points worth knowing.
What is reishi?
Reishi is the common name for Ganoderma lucidum and closely related species such as Ganoderma lingzhi. It’s a woody, shiny, kidney-shaped bracket fungus that grows on hardwood trees. It’s far too tough and bitter to eat like a button mushroom. Instead, it’s traditionally sliced and simmered for a long time to make a tea or decoction.
In Chinese and Japanese traditions, reishi was prized and depicted in art as a symbol of health and long life. Wild reishi was rare, so it was once reserved for the wealthy. Today it’s widely cultivated.
What’s in it?
Researchers are mainly interested in two groups of compounds:
- Polysaccharides, especially beta-glucans, which have been studied for their effects on the immune system.
- Triterpenes (such as ganoderic acids), which give reishi its bitter taste and have shown various activities in lab studies.
Amounts vary a lot between the fruiting body, the spores and the mycelium, and between preparation methods. That makes it hard to compare products and studies.
Reishi and cancer: what Cochrane found
Reishi is often promoted to people with cancer. In 2016, the Cochrane Collaboration reviewed the randomised trials. It found five trials, all of which used reishi alongside conventional treatment rather than instead of it. The reviewers reported some signs that patients given reishi might respond better to chemotherapy or radiotherapy and have better quality of life, but the trials were of low quality and there was no evidence it improved long-term survival (Jin et al., 2016). Their conclusion was that reishi could be considered an add-on at most, and should not replace standard treatment.
A 2023 review of clinical studies of medicinal mushroom supplements in cancer reached a similar view: interesting signals, but small studies and not enough to change practice (Narayanan et al., 2023).
Heart health: no clear benefit
Another Cochrane review looked at reishi for cardiovascular risk factors such as blood pressure, cholesterol and blood sugar in people with type 2 diabetes or high blood pressure. It found no significant benefit compared with placebo across four trials (Klupp et al., 2015). The reviewers said the evidence didn’t support using reishi for these risk factors.
Stress, sleep and fatigue
Reishi is often sold for calm and sleep. The human evidence is thin. One older randomised trial of a reishi polysaccharide extract in people with fatigue-related symptoms (neurasthenia) reported improvements compared with placebo (Tang et al., 2005), but it hasn’t been well replicated. Put plainly: results are limited and mixed, and we don’t yet know whether reishi helps with stress or sleep.
The liver safety question
Reishi is generally well tolerated, but there are published case reports of liver injury linked to reishi products, including one in the Journal of Hepatology (Yuen et al., 2004) and a 2023 case report and literature review (Guedikian et al., 2023). These cases are rare and often involved concentrated powders, but they’re a reminder that “natural” doesn’t mean risk-free.
How it’s traditionally used
Dried reishi slices are usually simmered gently in water for 30 minutes to two hours, sometimes with other ingredients like dates or ginger to soften the bitterness. The resulting tea is earthy and quite bitter. Some people reuse the slices for a second batch.
Who should take care?
We’re not aware of a current TGA safety advisory specific to reishi. However:
- Signs of liver problems: stop and see a doctor if you notice yellowing skin or eyes, dark urine, nausea, unusual tiredness or abdominal pain.
- Blood-thinning medicines or bleeding disorders: reishi may affect blood clotting.
- Blood pressure and diabetes medicines: possible additive effects.
- Immune-suppressing medicines or organ transplants: reishi may affect immune activity.
- Cancer treatment: always tell your oncology team before using any mushroom supplement.
- Upcoming surgery, pregnancy or breastfeeding: avoid concentrated products and seek advice.
The bottom line
Reishi has a remarkable history and real scientific interest. But Cochrane reviews found no clear benefit for heart risk factors and only low-quality evidence as an add-on in cancer, and evidence for stress and sleep is thin. Enjoy it as a traditional tea if you like, be aware of the rare liver reports, and talk to your health professional first if you have a medical condition.
This article is general information only and is not medical advice. It is not about any specific product. Talk to your GP or pharmacist about your own health. Safety information is current as at 24 October 2026; always check the TGA website for the latest advice.
References
- Jin X, et al. Ganoderma lucidum (Reishi mushroom) for cancer treatment. Cochrane Database Syst Rev. 2016. https://pubmed.ncbi.nlm.nih.gov/27045603/
- Narayanan S, et al. Medicinal mushroom supplements in cancer: a systematic review of clinical studies. Curr Oncol Rep. 2023. https://pubmed.ncbi.nlm.nih.gov/36995535/
- Klupp NL, et al. Ganoderma lucidum mushroom for the treatment of cardiovascular risk factors. Cochrane Database Syst Rev. 2015. https://pubmed.ncbi.nlm.nih.gov/25686270/
- Tang W, et al. A randomized, double-blind and placebo-controlled study of a Ganoderma lucidum polysaccharide extract in neurasthenia. J Med Food. 2005. https://pubmed.ncbi.nlm.nih.gov/15857210/
- Yuen MF, et al. Hepatotoxicity due to a formulation of Ganoderma lucidum (lingzhi). J Hepatol. 2004. https://pubmed.ncbi.nlm.nih.gov/15464254/
- Guedikian R, et al. Ganoderma lingzhi (Reishi mushroom)-induced acute liver injury in the setting of alcohol use: a case report and review of the literature. Cureus. 2023. https://pubmed.ncbi.nlm.nih.gov/37885515/
