Evidence explainerReishi mushroom

Reishi Mushroom Benefits: Few Human Trials, and the Biggest Review Found No Effect

Reishi has a 2,000-year reputation. The human evidence is thin: a Cochrane review found no change in blood sugar, cholesterol or blood pressure, and small trials measured short-lived lab markers.

By Kymata Health editorial teamPublished October 9, 2026Last reviewed October 9, 2026

Medical review pending. Written by our editorial team from the studies cited below; a credentialed clinician has not reviewed it yet. Educational only, not medical advice.

Key takeaways

  • A Cochrane review found no significant reduction in HbA1c, cholesterol or body-mass index with 1.4 to 3 g/day over 12 to 16 weeks [1].
  • Fasting glucose did not improve, and blood pressure did not differ from placebo [1].
  • In 10 volunteers, a single 1.1 g amount raised plasma antioxidant capacity, peaking at 90 minutes [2].
  • In 16 healthy volunteers, 4 g/day for 10 days did not significantly change immune cell counts [3].

Safety at a glance

From our Reishi mushroom monograph. Published interactions and cautions only, each with its source.

Interactions

  • Alcohol. A published case describes acute liver injury after reishi powder taken with alcohol, with labs back to normal at two-week follow-up.[5]

Who should be careful

  • Liver concerns. LiverTox notes reishi has been implicated in rare single cases of acute liver injury, although other causes were often not adequately excluded; one reported case involved reishi powder with alcohol.[4][5]
  • Before you start. Talk to your pharmacist or clinician before adding this supplement, especially if you take prescription medicines, are pregnant or breastfeeding, or have a chronic health condition.[4]

Full Reishi mushroom safety section

The evidence, graded

Pulled from our monograph evidence tables. Grades follow our evidence-grading policy.

  • Grade CNo effectHbA1c, cholesterol and body-mass indexReishi mushroom · Meta-analysis · n=130 · 2015 · PMID 25686270No statistically or clinically significant reduction in HbA1c, total or LDL cholesterol, or body-mass index; fasting glucose did not improve, and blood pressure and triglycerides did not differ. Adverse events were 1.67 times as likely with reishi over four months (confidence interval crossing 1), none serious.
  • Grade DImprovedBlood and urine antioxidant markersReishi mushroom · Crossover RCT · n=10 · 2004 · PMID 14630595Plasma antioxidant capacity rose after a single amount (peak at 90 minutes) and urine antioxidant capacity rose 29% within 3 hours. After 10 days, fasting plasma alpha-tocopherol and urine antioxidant capacity increased.
  • Grade DNo effectShort-term safety and immune cell countsReishi mushroom · RCT · n=16 · 2007 · PMID 17597499No adverse effects compared with placebo on questionnaires, ECG, blood counts, blood chemistry or urinalysis. CD4, CD8 and CD19 counts did not change; a CD56 rise was not statistically significant.

Blood sugar, cholesterol and blood pressure

A 2015 Cochrane review found 5 trials (398 participants) of Ganoderma lucidum; the 3 with usable data compared 1.4 to 3 g/day with placebo for 12 to 16 weeks in people with type 2 diabetes [1].

Reishi was not associated with a statistically or clinically significant reduction in HbA1c (130 participants), total or LDL cholesterol, or body-mass index (107 participants) [1]. Fasting glucose did not improve [1].

Antioxidant markers

In a crossover study of 10 healthy volunteers, a single 1.1 g amount raised plasma antioxidant capacity with a peak at 90 minutes, and urine antioxidant capacity rose about 29% [2]. Whether a short rise in a blood marker matters for health is unknown.

Immune cells

In a 10-day trial of 16 healthy volunteers taking 2 g of extract twice daily, CD4, CD8 and CD19 counts did not change, and a CD56 rise did not reach statistical significance [3]. The authors called for a longer trial [3].

For liver reports and other safety points, read reishi mushroom side effects.

Quick answers

Does reishi help sleep?

None of the trials in our sources measured sleep; they measured metabolic markers, antioxidant capacity and immune cells [1][2][3].

How much reishi was used in trials?

Amounts ranged from 0.72 g/day over 10 days to 4 g/day of extract [2][3].

Is reishi good for the immune system?

In the one small trial in our sources, immune cell counts did not change significantly over 10 days [3].

Keep reading

Full monographs

Related articles

Browse the full Supplement & Nutrient Encyclopedia or all supplement articles.

References

  1. [1]Ganoderma lucidum mushroom for the treatment of cardiovascular risk factors. Cochrane Database Syst Rev, 2015. PMID 25686270
  2. [2]Ganoderma lucidum ('Lingzhi'); acute and short-term biomarker response to supplementation. Int J Food Sci Nutr, 2004. PMID 14630595
  3. [3]Safety and tolerability of Ganoderma lucidum in healthy subjects: a double-blind randomized placebo-controlled trial. Am J Chin Med, 2007. PMID 17597499

Reishi mushroom and other dietary supplements are not intended to diagnose, treat, cure or prevent any disease, and these statements have not been evaluated by the FDA. Talk to your clinician or pharmacist before starting a supplement, especially if you take prescription medicines. This page has no product or affiliate links.

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