Shiitake mushroom dermatitis

Shiitake mushroom dermatitis (SMD) is a cutaneous condition with a flagellate morphology that occurs after eating large amounts of raw or partially cooked shiitake mushrooms. The rash is thought to be a toxic reaction to a starch-like component of the shiitake mushroom. This component, known as lentinan, breaks down with heat, so this reaction is seen only when the mushrooms are eaten raw or partially cooked.

Recently however, it has been proposed that log-grown shiitake is perhaps the real cause [JEADV 2016;30;197].


A red, inflamed, flagellate dermatitis is seen.

Differential Diagnosis

See flagellate dermatoses.


The skin lesions disappear from 3 days to 2 weeks. As the main complaint is itching, topical steroids and oral antihistamines or sedatives may be recommended.


Dermatology Online Journal 17(12)

SMD in a pregnant woman. López-Núñez M, et al. Gestante con erupción flagelada. Actas Dermosifiliogr.2012;103:155–6..

Additional Pictures

Shiitake mushroom dermatitis


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