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Amanita smithiana mushroom poisoning

Patrick West, MD
Section Editor
Stephen J Traub, MD
Deputy Editor
James F Wiley, II, MD, MPH


Amanita smithiana is a mushroom found primarily on the West Coast of North America. Toxic ingestion causes a syndrome of acute gastroenteritis within minutes to hours of consumption followed by delayed onset renal failure within one week. Although uncommon, Amanita smithiana poisoning has increased in frequency over the last two decades [1]. It represents the only known mushroom poisoning syndrome where ingestion of a single type of mushroom can have immediate acute effects that are followed by serious delayed toxicity (table 1).

This topic will discuss the epidemiology, toxicity, clinical manifestations, and management of Amanita smithiana mushroom poisoning. Evaluation and management of other poisonous mushrooms are discussed separately. (See "Clinical manifestations and evaluation of mushroom poisoning" and "Management of mushroom poisoning" and "Amatoxin-containing mushroom poisoning (eg, Amanita phalloides): Clinical manifestations, diagnosis, and treatment".)


Amanita smithiana is a white mushroom that grows in pine forests on the West coast of North America, primarily from British Columbia to Northern California, though they have been observed as far south as the mountains of New Mexico [2]. Ingestion has also been reported in Southeast Asia [3]. A. smithiana mushrooms grow in the autumn until the time of the first frost, typically growing near dead or rotting wood.

Toxicity from Amanita smithiana was first described in 1964, although its toxic effects were misattributed to A. phalloides [4]. Following the initial report, almost 30 years passed without a documented case. In the 1990s, A. smithiana mushroom poisoning became more commonly described in association with increasing culinary popularity and economic value of the matsutake or pine mushroom (Tricholoma magnivelare), which has a similar habitat and appearance [2,5-7]. Publication of the book "Matsutake Mushroom: White gold rush of the 1990s" in 1997 coincided with the largest spike in reports of these ingestions in 1997 and 1998 [8]. In all cases of poisoning reported to date, A. smithiana have been ingested by individuals collecting and preparing the look-alike matsutake or pine mushroom (picture 1) for personal culinary use.

Matsutake mushrooms are also extremely desirable for commercial culinary use. Matsutakes have been gathered in regions where A. smithiana is native and sold to restaurants in areas where A. smithiana is not, making poisoning possible outside of the West coast of North America or Southeast Asia [8].

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Literature review current through: Oct 2017. | This topic last updated: May 25, 2017.
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