CA Mushrooms

Toxic Fungi of Western North America

by Thomas J. Duffy, MD

Miscellaneous toxins

Auricularia polytricha, a flattened ear-shaped mushroom used in Chinese cooking, produces an anticoagulant effect. In 1980, a U.S. case of “Szechwan Purpura” was reported in the New England Journal of Medicine. A 32-year-old U.S. researcher (during an experiment using his own blood platelets for clotting) found after some 50 trials one morning that his platelets would not agglutinate or release serotonin on exposure to epinephrine. (211) On physical examination, he had a few small bruises on the legs. Tests, not requiring platelets, were normal. He and his co-workers were able to trace the aspirin-like effect back to Mo-er (the Mandarin name for Auricularia polytricha). This mushroom inhibited platelet response in the researcher and other volunteers for 3-24 days. Like aspirin (another inhibitor of platelets), this mushroom should not be ingested prior to surgery or by patients with poor blood clotting.

Auricularia polytricha
Auricularia polytricha photo © Tom Duffy

Western physicians thus became aware that Auricularia polytricha inhibits the tiny blood platelets that initiate blood clotting in the small vessels and capillaries of the body. This mushroom is a dark rubbery, irregular ear-like fungus known in Asian markets as “wood ears”. This mushroom is especially common on trees along canals and waterways in the damp, fertile province of Szechwan. Like the discovery of penicillin, it occurred in the course of a different investigation.

Cookbooks commonly confuse the fleshier Auricularia polytricha with the smaller and thinner Auricularia auricularia, which has no effect on platelets and which Cantonese cooking uses in its contrast of textures. The more spicily sauced cuisines of Szechwan and Hunan use the thicker Auricularia polytricha more for soaking up their richer sauces than for texture.

The red-pored Boletus pulcherrimus Thiers and Halling [formerly Boletus eastwoodiae (Murril) Saccardo and Trotter] ordinarily produces only gastrointestinal symptoms, but may have additional toxicity. An Oregon husband and wife began with typical gastrointestinal symptoms in a 1974 poisoning. The husband, however, died suddenly and his autopsy showed small bowel death from lack of blood supply. (3) There was either clotting of vessels leading to the mid-gut or a lack of blood supply due to a drop of blood pressure. Causes could have been dehydration, a narrow artery to the small bowel or a direct toxic effect on blood pressure or on blood clotting.

Boletus pulcherrimus
Boletus pulcherrimus photo © Fred Stevens

Suillus species have generally not caused any symptoms, other than occasional gastrointestinal ones, in North America. However, there have been a few reports of other toxicity, including one from Poland, of hemolysis. (207)

Boletus amygdalinus: The San Francisco Poison Control Center reported in 1998 that at least two persons of Russian extraction, seen in a San Francisco Bay Area emergency room for mushroom poisoning, were subsequently hospitalized with markedly abnormal liver tests. The Poison Control Center asked two of the MSSF member to examine the boletes they had collected. One of the sons brought the remaining boletes to the Webmaster of, Michael Wood, and to a former pupil of Dr. Harry Thiers, Fred Stevens. The specimens were readily identified as Boletus amygdalinus (Thiers) Thiers a species indigenous to central California. The MSSF’s Toxicology Committee did not examine the actual hospital records. The identification, however, was solid and the specimen showed the pip-shaped spores as well as other characteristic features. (208a) Any bolete causing liver or kidney damage should be reported in as much detail as possible; boletes have always been considered relatively safe for amateur collecting, causing at worst only gastrointestinal misery.

Boletus amygdalinus
Boletus amygdalinus photo © Michael Wood

Two Clitocybe species with high acromelic acid levels are known to produce a bizarre acromelalgia. A Clitocybe in France (Clitocybe amoenolens) has caused swelling, reddening and severe pain in the limbs. Clitocybe acromelalga in Japan produces the same syndrome. The toxins (acromelic acids) were the same. Such a poisoning may eventually be found here, possibly in one of the brown clitocybes. (214) The pain produced by these fungi responded poorly to opiates. However, neuralgic pain often responds to higher doses of narcotics, to antidepressant drugs (such as nortryptine) and to some of the anticonvulsant medications (neurontin, lamictal, mexiletine and tegretol).

Morchella and Gyromitra/Helvella. See rhabdomyolyis in Psilocybe cubensis below.

Phallus impudicus poisoning was reported to produce severe allergic symptoms in two patients. One lady had dramatic reddening of her hands followed by hives over her entire body with this "stink horn". (91) The common name refers to the unpleasant odor which is so distinctive and strong in the mushroom that one is thereafter able to smell the fungal mycelia in the ground, even in the absence of the fruiting body.

Psilocybe cubensis. This psychoactive (and often cultivated) mushroom surprisingly caused rhabdomyolysis in one poisoning. The NAMA national data base maintained by Dr. Kenneth Cochran recorded that case and additionally two more cases of muscle break-down following mixed meals of morels and false morels (Morchella and Gyromitra/Helvella). (212)

Ptychoverpa bohemica (Kromb.) Boud. was previously placed in the genus Verpa. This mushroom has produced GI symptoms at times, but the most remarkable poisonings have produced decreased muscular coordination, even to the point of being unable to write. (209,210) One theory is that small amounts of Gyromitrin are present. However, this conception is inconsistent with Gyromitrin’s threshold effect. What occurs with remarkable consistency, however, is a predominant CNS symptom of incoordination suggesting a novel toxin. The Thiers Herbarium in San Francisco contains only two collections of Ptychoverpa bohemica. This species is more common in the PNW and in the East.

Tricholoma flavovirens, a choice edible in the U.S., has caused rhabdomyolysis in twelve pot-hunters in France who had eaten large amounts at three or more meals. The victims developed some muscle symptoms at 24-72 hours with pain and weakness. The group of 12 pot-hunters delayed coming in for medical treatment and also had dark urine and severe sweating. (213,214)