Avoid if known allergy/hypersensitivity to shiitake mushrooms. Rash, toxic epidermal necrolysis, and photodermatitis may occur from contact or ingestion.

Allergic contact dermatitis has been induced by shiitake hyphae (filaments).

Mushroom workers exposed to shiitake spores by inhalation have experienced hypersensitivity pneumonitis.

A case report exists of an anaphaylactoid (life-threatening) reaction in a patient with HIV who was taking lentinan.

Most minor adverse effects are believed to be caused by lentinan, the polysaccharide derivative of shiitake. There has been one report each of depression, rigor, fever, chills, and abnormal blood cell counts (granulocytopenia); elevated liver enzymes was reported in one study following treatment with lentinan in cancer patients.

Shiitake can cause abdominal discomfort and abnormal blood cell counts (eosinophilia) when taken by mouth. Abdominal obstruction and death was reported due to the ingestion of a whole shiitake mushroom. Temporary diarrhea and abdominal bloating may occur after taking high amounts of shiitake.

Mushroom workers exposed to shiitake spores by inhalation have experienced hypersensitivity pneumonitis (lung inflammation).

Rapid IV infusion of lentinan, the polysaccharide derivative of shiitake, to advanced cancer patients was reported to cause anterior chest depression and dryness of the throat in one study; slow infusion relieved these symptoms.

Back pain and leg pain has been reported following administration of lentinan in cancer patients.

Shiitake can cause "shiitake" dermatitis and possibly photosensitivity, when taken by mouth. Allergic contact dermatitis has been induced by shiitake hyphae (filaments). A 44 year-old woman presented with an eight-month history of hand and face dermatitis (rash) that developed after working for 2.5 years in a Lentinus edodes farm. Within three months of ceasing work at the farm, her symptoms resolved completely.

Shiitake mushroom is not recommended in pregnant or breastfeeding women in medicinal amounts due to a lack of available scientific evidence.

Traditionally, 6-16 grams of the whole, dried shiitake mushroom has been ingested daily. It is typically eaten in soups or taken as a decoction (i.e. boiled for 10-20 minutes, cooled, strained, and drunk).

1-3 grams of Lentinus edodes mycelium (LEM) has been taken two to three times per day.

Shiitake-containing capsules have been taken three times daily for six months.

4 grams of shiitake powder has been taken daily for ten weeks.

Various doses have been given by a qualified healthcare provider along with chemotherapy and in HIV and surgical patients.

Intranasal application of lentinan has been studied at a dose of 1 milligram per kilogram, used three times at two-day intervals.

Insufficient available evidence to recommend.

Although not well studied in humans, lentinan and shiitake extracts may interact with antifungals, antivirals, antioxidants, and immunomodulators. Caution is advised.

Lentinan has been used as an adjunct with cancer therapies to prolong survival time and increase quality of life.

Based on preliminary animal study, shiitake may reduce blood levels of free cholesterol, triglycerides, and phospholipids.

In a laboratory study, essential oil from shiitake inhibited platelet aggregation and therefore may increase the risk of bleeding when taken with drugs that also increase bleeding risk like warfarin (Coumadin®) or ibuprofen (Advil, Aleve®). Lentinan, the polysaccharide derivative of shiitake, may cause mildly abnormal blood cell counts (thrombocytopenia).

Lentinus edodes has been shown to inhibit cyclooxygenase activity in laboratory study and therefore may interact with drugs like Tylenol® or Celebrex®.

Mushroom polysaccharides, especially beta-glucans such as lentinan from Lentinus edodes, may interfere with the way the liver breaks down certain drugs (through suppression of CYP1As). Consult a qualified healthcare professional, including a pharmaicist, to check for interactions.

Taking didanosine (ddI, Videx®), the nucleoside reverse transcriptase inhibitor (NRTI) antiretroviral drug for HIV, with lentinan (the polysaccharide derivative of shiitake) may help to increase CD4 levels in HIV positive patients.

Lentinan may cause increased sun sensitivity that can be worsened by drugs like Retin-A® and tetracycline antibiotics.

Although not well studied in humans, lentinan and shiitake extracts may interact with antifungals, antivirals, antioxidants, and immunomodulators. Caution is advised.

Based on preliminary animal study, shiitake may reduce blood levels of free cholesterol, triglycerides, and phospholipids.

In a laboratory study, essential oil from shiitake inhibited platelet aggregation and therefore may increase the risk of bleeding when taken with herbs or supplements that also increase bleeding risk like garlic or saw palmetto. Lentinan, the polysaccharide derivative of shiitake, may cause mildly abnormal blood cell counts (thrombocytopenia).

Mushroom polysaccharides, especially beta-glucans such as lentinan from Lentinus edodes, may interfere with the way the liver breaks down certain herbs and supplements (through suppression of CYP1As). Please check with your doctor and pharmacist to screen for potential interactions.

Lentinan may cause increased sun sensitivity that can be worsened by herbs and supplements like St. John's wort or capsaicin.