Reishi mushrooms are sometimes referred to as Ling Chih or Ling Zhi. Its medicinal use dates back to some of the oldest Chinese pharmacopoeia written, documented in the first century B.C. Reishi was highly valued at this time, and had the most medical applications of all medicines contained in the pharmacopoeia. Reishi is difficult to find growing in the wild, as it is very slow growing, making it a highly valued herb. More recently, however, it has been successfully cultivated ‘in captivity’ and is now widely available in various dietary supplements.
Despite the long history of reishi use in traditional medicine, intensive research investigations are just beginning because of it new found availability. Studies aim for an understanding of reishi’s relevance in human health. Current trials are focused on:
- conditions of the cardiovascular system
- antiviral and antibacterial properties
- hepatoprotective effects
- anticancer benefit
- immunological functiong
- anti-aging properties
The medicinal parts of the mushroom are the fruiting body and mycelium, or root-like projections.  The fruiting body is what is normally referred to as the mushroom, or aboveground part of the fungus. The active constituent of this mushroom are not well known; however substances similar to protease inhibitors (anti-viral medications) have been identified in large amounts, as well as adenosine, a specific type of amino acid. [2, 3]
Reishi mushroom is used for a wide variety of conditions based on many of its purported effects. Not all uses listed here have been backed by scientific evidence, however they are worth mentioning due to the many empirical benefits noted when reishi is used as a therapeutic agent. These uses include: immune system enhancement, hepatitis, anti-viral, high blood pressure, high cholesterol, asthma, lung conditions, HIV and AIDS, cancer, insomnia, fatigue, herpes, and poisoning.
Some of the documented effects of reishi mushroom include benefit in preventing blood clotting, high cholesterol, HIV, cancer, herpes, diabetes, and liver protection. [4, 11]
Reishi is perhaps best known as an immune system modulator; it is often combined in packages with other Chinese medicines containing mushrooms. Taking mushrooms for their immune-enhancing effects has gained much popularity with the advent of antibiotic-resistant organisms.
The typical dose of reishi mushroom is 1.5 to 9 grams of the dried fungus per day. Reishi is also available as a dried powder, tea, or tincture delivery forms.  1 to 1.5 grams of powder may be used per day, and 1 milliliter of tincture is an applicable daily dose.
Reishi Side effects
Side effects of reishi are limited to dryness of the mouth and nose, upset stomach, nosebleeds, and bloody stools (after an extended use).  There is some concern of reishi allergy when the reishi-containing wine is drunk, or exposure to reishi spores occurs. 
Reishi General interactions (supplement, herb, food, lab)
Reishi may have certain anticoagulant and hypotensive effects. [4, 14] Therefore, when using other herbs or supplements with these actions, caution should be used.
Reishi Drug interactions
As with other supplements or herbs with anticoagulant or hypotensive effects, caution should be used when using reishi with pharmaceutical drugs with the same effects, as this may lead to enhanced drug activity (additive effect).
People with low blood pressure or low platelet count (thrombocytopenia) may experience adverse effects when taking reishi due to its possible anticoagulant and hypotensive effects.
1 McGuffin M, Hobbs C, Upton R, Goldberg A, eds. American Herbal Products Association’s Botanical Safety Handbook. Boca Raton, FL: CRC Press, LLC 1997.
2 Min BS, Nakamura N, Miyashiro H, et al. Triterpenes from the spores of Ganoderma lucidum and their inhibitory activity against HIV-1 protease. Chem Pharm Bull (Tokyo) 1998;46:1607-12.
3 Gau JP, Lin CK, Lee SS, et al. The lack of antiplatelet effect of crude extracts from ganoderma lucidum on HIV-positive hemophiliacs. Am J Chin Med 1990;18:175-9.
4 Tao J, Feng KY. Experimental and clinical studies on inhibitory effect of ganoderma lucidum on platelet aggregation. J Tongji Med Univ 1990;10(4):240-3.
5 Wasser SP, Weis AL. Therapeutic effects of substances occurring in higher Basidiomycetes mushrooms: a modern perspective. Crit Rev Immunol 1999;19:65-96.
6 el-Mekkawy S, Meselhy MR, Nakamura N, et al. Anti-HIV-1 and anti-HIV-1-protease substances from Ganoderma lucidum. Phytochem 1998;49:1651-7.
7 Wang SY, Hsu ML, Hsu HC, et al. The anti-tumor effect of Ganoderma lucidum is mediated by cytokines released from activated macrophages and T lymphocytes. Int J Cancer 1997;70:699-705.
8 Kim HS, Kacew S, Lee BM. In vitro chemopreventive effects of plant polysaccharides (Aloe barbadensis miller, Lentinus edodes, Ganoderma lucidum and Coriolus versicolor). Carcinogenesis 1999;20:1637-40.
9 Hijikata Y, Yamada S. Effect of Ganoderma lucidum on postherpetic neuralgia. Am J Chin Med 1998;26:375-81.
10 Hikino H, Ishiyama M, Suzuki Y, et al. Mechanisms of hypoglycemic activity of ganoderan B: a glycan of Ganoderma lucidum fruit bodies. Planta Med 1989;55:423-8.
11 Kim DH, Shim SB, Kim NJ, et al. Beta-glucuronidase-inhibitory activity and hepatoprotective effect of Ganoderma lucidum. Biol Pharm Bull 1999;22:162-4.
12 Reishi. Mothernature encyclopedia. http://www.pdrhealth.com/drug_info/nmdrugprofiles/herbaldrugs/101840.shtml. (Accessed 7 November 1999). 1 Ibid
13 Singh AB, Gupta SK, Pereira BM, et al. Sensitization to Ganoderma lucidum in patients with respiratory allergy in India. Clin Exp Allergy 1995;25:440-7. 4 Ibid
14 Lee SY, Rhee HM. Cardiovascular effects of mycelium extract of Ganoderma lucidum: inhibition of sympathetic outflow as a mechanism of its hypotensive action. Chem Pharm Bull (Tokyo) 1990;38:1359-64.