Shiitake Dermatitis | What you need to know

Shiitake Dermatitis | What you need to know

What is Shiitake Dermatitis?

Shiitake mushroom dermatitis is a highly pruritic dermatitis characterised by 1mm ochrogenic disseminated erythematous micropapules seen in linear clustering, due to koebnerization from the patients scraping or scratching around the rash. It is caused by the consumption of shiitake mushrooms, first in 1977.

Although rarely seen outside China and Japan, because shiitake consumption is lower outside of those regions, a well-established link is made between flagellated dermatitis and ingestion of shiitake mushrooms (Lentinula edode). Bleomycin ingestion can cause similar findings as well. On physical examination, a key difference between these two is that changes to post-inflammatory hyperpigmentation are usually seen in flagellated dermatitis caused by bleomycin, whereas these are usually absent from flagellated dermatitis caused by Shiitake mushrooms.

The average onset time after ingestion of shiitake mushrooms is typically 24 hours, with a range from 12 hours to 5 days. Most patients fully recover within 3 weeks, both with and without therapy.

Although the pathogenesis of shiitake-induced flagellated dermatitis is unclear, most theories suggest that it is a toxic reaction to lentinan, a polysaccharide isolated from shiitake mushrooms. However, both type I and type IV allergic hypersensitivity were also supported, with 24-hour median time of onset, resolution within 3-21 days, intense pruritus, benefits from steroids and antihistamines, and lack of clustered outbreaks among persons exposed to shared meals with shiitake mushrooms. Most cases reported soon after their emergence were from the consumption of raw shiitake mushrooms, but some cases have since been reported following the consumption of cooked mushrooms.

If you don’t think you’ll suffer from this allergic reaction, you can find our favorite supplements containing Shiitake Mushrooms on the following page of our website to learn more.

Best Shiitake Mushroom Supplement

Additional Resources:

Shiitake mushroom nutrition

How to prepare shiitake mushrooms

About the author

Bruce Wilson

I've studied Mycology and Forest Pathology and love creating content to help other learn more about my passion. Follow along as I continue to explore the amazing world of functional fungi!

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