Reishi Mushroom Benefits and Side Effects: What Men Should Know

Short answer: The best supported reishi mushroom benefits in humans are modest: small trials suggest it may ease urinary symptoms in older men, reduce fatigue in one Chinese trial, and add some immune and quality of life support for people already receiving cancer treatment. Claims about sleep, testosterone, blood sugar and cholesterol rest mostly on animal work or trials that found no effect. Reishi is usually well tolerated, but it can raise bleeding risk with blood thinners, and powdered reishi has been linked to rare cases of serious liver injury.

Key Takeaways

• Reishi (Ganoderma lucidum) is a woody medicinal mushroom long used in traditional Chinese and Japanese practice, mainly as a hot water extract or tea.
• The strongest human signal for men is a pair of small trials on lower urinary tract symptoms, where an extract improved symptom scores but did not change urine flow, prostate size or PSA.
• A 2016 Cochrane review of 5 trials (373 people) found reishi was not proven as a cancer treatment, though it may help as an add-on to standard care.
• Common side effects include nausea, dry mouth, dizziness, digestive upset and, ironically for a “sleep” herb, insomnia.
• Talk to a doctor first if you take warfarin or other blood thinners, immunosuppressants, or have liver disease or drink heavily.

What Is Reishi Mushroom?

Reishi is the Japanese name for Ganoderma lucidum, a glossy, reddish brown shelf mushroom that grows on hardwood trees. In China it is called lingzhi. It is too tough and bitter to eat, so it has traditionally been sliced and boiled into tea or prepared as an extract. Modern supplements come as capsules, powders, tinctures, spore powder and “mushroom coffee” blends.

Researchers are interested in two main groups of compounds. The first is polysaccharides, especially beta glucans, which are studied for their effects on immune cells. The second is triterpenes (such as ganoderic acids), which give reishi its bitter taste and are studied for anti inflammatory and liver related activity in the lab. Memorial Sloan Kettering Cancer Center lists the popular uses as boosting immunity, increasing strength and stamina, lowering cholesterol and easing lower urinary tract symptoms in men.^[1]

Fruiting body, mycelium and spores

Products differ a lot. Some use the fruiting body (the mushroom itself), some use mycelium grown on grain, and some use the spores. Extracts concentrate certain compounds, while raw powder is simply the dried mushroom ground up. This matters for both benefits and safety, because most clinical trials used specific extracts, and the serious liver reports discussed below involved powdered products.^[1][5][6]

Reishi Mushroom Benefits: What Human Studies Show

Many websites list dozens of reishi mushroom benefits. When you separate human trials from cell and animal studies, the list gets much shorter. Here is what the clinical evidence actually supports.

Urinary symptoms in older men

This is the benefit most relevant to men. In a Japanese double blind, placebo controlled, dose ranging trial, 50 men aged 50 or older with mild urinary symptoms took an ethanol extract of Ganoderma lucidum at 0.6 mg, 6 mg or 60 mg daily, or placebo. Symptom scores (the International Prostate Symptom Score, or I-PSS) improved differently between groups at weeks 4 and 8, the extract was well tolerated, and the authors recommended 6 mg daily. Peak urine flow, leftover urine, prostate volume and PSA did not change.^[4] A follow up trial in men over 49 found that 6 mg per day for 12 weeks lowered I-PSS scores compared with placebo, but quality of life and other secondary outcomes did not change.^[2]

In other words, men felt somewhat better on a questionnaire, but the measurable prostate markers stayed the same. Urinary symptoms can have many causes, so they deserve a proper medical workup rather than self treatment.

Fatigue

A multicenter, double blind, placebo controlled trial in China gave 5.4 g per day of a reishi extract (Ganopoly) for 8 weeks to people diagnosed with neurasthenia, a label for chronic fatigue and poor concentration. Participants reported less fatigue than those on placebo.^[2] That is an encouraging signal, but it is one trial, in one specific population, at a dose far higher than most capsules provide.

Immune markers and cancer care

The Cochrane review by Jin and colleagues pooled 5 randomized trials with 373 participants. Adding reishi to chemotherapy or radiotherapy was linked to a higher chance of tumor response, but the result was not statistically conclusive, and reishi alone did not shrink tumors. Some trials reported higher counts of certain immune cells (CD3, CD4 and CD8 lymphocytes), and four reported better quality of life. The trial quality was generally poor, all participants were Chinese, and none measured long term survival. The authors concluded there was not enough evidence to use reishi as a first line cancer treatment, although it may be considered as an add on because it was well tolerated.^[3]

Blood sugar, cholesterol and blood pressure

Results here are mostly disappointing. In a 16 week trial of 84 adults with type 2 diabetes and metabolic syndrome, 3 g per day did not significantly change HbA1c or fasting glucose versus placebo. In a small crossover trial of 23 people taking 1.44 g per day, reishi did not meaningfully change cholesterol or blood pressure.^[2] MSKCC notes that randomized trials do not support reishi for reducing cardiovascular risk factors in type 2 diabetes.^[1]

Sleep, stress and recovery

Reishi is often marketed as a calming “sleep mushroom.” Most of that reputation comes from traditional use and animal research. MSKCC mentions one study that reported lower anxiety, but neither MSKCC nor the Drugs.com monograph describes solid human sleep trials.^[1][2] Insomnia actually appears on the list of reported side effects in both MSKCC and the Cochrane review.^[1][3] If better sleep is your main goal, a consistent sleep routine is a more reliable starting point.

Evidence at a Glance

How Reishi Is Used and Typical Amounts

There is no single official dose because products vary so much. For reference, the Chinese Pharmacopoeia lists 6 to 12 g of extract daily, traditional practitioners commonly use 0.5 to 1 g daily, and clinical trials of the Ganopoly extract used up to 5.4 g daily for 12 weeks.^[2] At the other end of the scale, the urinary symptom trials used only 6 mg of a concentrated ethanol extract.^[4]

Practical tips if you choose to try reishi:

• Read the label for the part used (fruiting body, mycelium or spores) and whether it is an extract or plain powder.
• Choose brands that publish exact amounts and use third party testing for identity and contaminants.
• Start low, stop if you notice digestive upset, rash, unusual bruising, dark urine or yellowing of the eyes, and tell your doctor.
• Give any trial at least several weeks, since the studies above ran for 8 to 16 weeks.

Reishi Mushroom Side Effects and Safety

Common side effects

Reported side effects include nausea, insomnia, dry mouth, constipation, diarrhea, itching, dizziness and vertigo, nosebleeds and skin irritation.^[1][2] In a small safety trial, healthy adults taking 4 g per day for 10 days showed no differences from placebo, and 1.5 g per day for 4 weeks did not change platelet or clotting function.^[2]

Liver injury reports

This is the most important safety issue. MSKCC notes that case reports have linked powdered reishi to liver toxicity, including one death from fulminant hepatitis.^[1] That fatal case, published in 2007, involved a person who switched from traditionally boiled lingzhi to lingzhi powder for one to two months.^[5][6] In a 2023 case report, a 47 year old man with fatty liver who took several tablespoons of reishi powder while drinking heavily developed acute liver injury, with ALT rising from 13 to 990 U/L. He recovered after stopping both, and the authors judged reishi the main likely cause, with alcohol and fatty liver as contributors.^[5]

The US Drug-Induced Liver Injury Network also lists reishi among the single ingredient supplements implicated in liver injury, and European liver guidelines advise clinicians to consider reishi as a possible cause.^[2] These events are rare, and the Cochrane review found no significant liver toxicity in its trials,^[3] but anyone with liver disease or heavy alcohol use should be cautious.

Drug interactions

• Blood thinners and antiplatelets (warfarin, aspirin, clopidogrel, NSAIDs): possible added bleeding risk; reishi extracts may prolong clotting test results.^[1][2]
• Immunosuppressants: reishi may enhance immune activity, which could work against these drugs.^[1]
• Chemotherapy: possible interaction with drugs that rely on free radicals; use only with your oncology team’s approval.^[1]
• Other medications: in lab studies reishi inhibited several liver enzymes (CYP2E1, CYP1A2 and CYP3A) that process many drugs; the clinical importance is unknown.^[1]
• Cancer blood tests: reishi spore powder may raise the tumor marker CA72-4 and confuse results.^[1]

Who Should Avoid Reishi or Talk to a Doctor First

• People taking anticoagulants, antiplatelets or regular NSAIDs, and anyone scheduled for surgery.
• Anyone on immunosuppressants, such as transplant recipients.
• People with liver disease, a history of liver injury or heavy alcohol use.
• People in cancer treatment, who should clear any supplement with their care team.
• People with autoimmune skin conditions, since MSKCC notes reishi may trigger or worsen them.^[1]
• Pregnant or breastfeeding women, since safety has not been established.^[2]

Reishi in Ultra Bann

Ultra Bann, a natural male vitality supplement by DL Bioproducts, includes 45 mg of reishi (Ganoderma lucidum) as one of seven botanicals in an 800 mg serving, alongside Thai Butea superba, Panax ginseng, Cynomorium songaricum, black ginger, tongkat ali and epimedium. Every amount is printed on the label, with no proprietary blend, and you take one capsule every 2 days. You can review the full ingredient label before buying.

To be clear about scale, 45 mg is far below the gram level amounts used in the fatigue, blood sugar and cancer studies above, so the reishi in Ultra Bann is a supporting botanical rather than a standalone reishi dose. The same safety advice applies: if you take blood thinners or immunosuppressants, or have liver concerns, ask your doctor before using any product that contains reishi. First orders ship free in the US and include a 60-day money-back guarantee, and you can find it in the Ultra Bann shop.

Frequently Asked Questions

What are the main reishi mushroom benefits for men?

The most specific human evidence for men involves lower urinary tract symptoms: small trials found a low dose extract improved symptom scores in men 50 and older, without changing prostate size or PSA. Evidence for energy, immunity and stress support is limited, and there is no good human evidence that reishi raises testosterone.

Is it safe to take reishi every day?

Short term daily use appeared well tolerated in trials lasting up to 16 weeks. Long term safety is less clear, and rare liver injury has been reported, mainly with powdered products. If you plan to take it daily for months, check with a doctor, especially if you take other medications.

Does reishi help you sleep?

Possibly for some people, but the evidence is mostly from animals. Human sleep trials are scarce, and insomnia is actually a reported side effect. Treat reishi as an experiment, not a sleep aid with proven effects.

Can reishi damage your liver?

It is uncommon, but yes, it has happened. Case reports link reishi powder to liver injury, including one fatal case of fulminant hepatitis, and a 2023 report described acute liver injury in a man combining reishi powder with heavy drinking. Stop taking it and see a doctor if you develop dark urine, yellow skin or eyes, or abdominal pain.

How long does reishi take to work?

Studies that found effects ran for 4 to 16 weeks. In the urinary symptom trial, differences showed up at weeks 4 and 8. Do not expect a noticeable effect after a single dose.

References

1. Memorial Sloan Kettering Cancer Center. About Herbs: Reishi Mushroom. Updated May 5, 2026. mskcc.org
2. Drugs.com. Reishi Mushroom (natural product monograph). drugs.com
3. Jin X, Ruiz Beguerie J, Sze DM, Chan GCF. Ganoderma lucidum (Reishi mushroom) for cancer treatment. Cochrane Database of Systematic Reviews. 2016, Issue 4. CD007731. cochrane.org
4. Noguchi M, Tomiyasu K, Nakiri M, et al. An extract of Ganoderma lucidum in men with lower urinary tract symptoms: a double-blind, placebo-controlled randomized and dose-ranging study. Nishinihon Journal of Urology. 2008;70(9):466-472. kyushu-u.elsevierpure.com
5. Guedikian R, Kim B, Singh G, Alexander R. Ganoderma lingzhi (Reishi Mushroom)-Induced Acute Liver Injury in the Setting of Alcohol Use: A Case Report and Review of the Literature. Cureus. 2023;15(9):e45953. pmc.ncbi.nlm.nih.gov
6. Wanmuang et al. Fatal fulminant hepatitis associated with Ganoderma lucidum (Lingzhi) mushroom powder. 2007. pubmed.ncbi.nlm.nih.gov

These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease. This article is for information only and is not medical advice.