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A Shiitake Mushroom Rash

By HERWriter
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Food Allergies related image Photo: Getty Images

Shiitake mushrooms are an Asian delicacy frequently added to stir-fries or used as a source of protein in vegetarian cooking. What may come as is surprise is that one can be “allergic” to undercooked shiitake mushrooms so it is suggested that people always cook them thoroughly before eating.

On February 18, 2011, the New York Times ran an article about a woman who developed a pretty severe red-lined rash all over her body. The rash was not particularly itchy nor was it painful. Her doctor was stumped so he called in other doctors to evaluate her. After examining the rash, one of the doctors paused for a moment then asked her if she had recently had shiitake mushrooms? Surprised, she said she had a few days before the outbreak as a sample sautéed in garlic and oil at a grocery store.

Apparently, the shiitake mushrooms were undercooked which left a starch-like substance in the mushrooms called lentinan that was not sufficiently broken down in the portion she ate. Heating lentinan prevents the body from having a toxic reaction to it when consumed. Unlike a true allergy, people who react to uncooked shiitake mushroom do not show a typical immune response in their blood levels nor do they develop classic symptoms of hives, itching and swelling. The response to shiitake mushrooms has been labeled as a toxic reaction rather than an actual allergy.

Interestingly, lentinan has been used as an anti-cancer agent. According to sloankettering.org, lentinan use has been studied extensively. The protein component of lentinan is called lentin, which has been found to have anti-fungal properties, reduce the growth of leukemia cells and suppress HIV viral enzyme activity. Lentinan has also been studied for use in prostate cancer suppression though the results did not show it alone could sufficiently prevent it. It is important to note that most clinical studies do not test patients using actual shiitake mushrooms but use extracts in powder form.

Shiitake mushroom do have natural health and nutritional benefits but they should never be eaten raw even if in the past one has not had any problems. Allergic or toxic reactions can occur even after years of exposure to a substance then without warning, the body can react even though the substance had never caused an outbreak before. Additionally, all mushrooms contain other molds and spores that could cause an actual allergic reaction so it is best to have a doctor evaluate any rash that occurs after consuming mushrooms.


Michele is an R.N. freelance writer with a special interest in woman’s health care and quality of care issues. Other articles by Michele are at www.helium.com/users/487540/show_articles

Add a Comment29 Comments

EmpowHER Guest
Anonymous (reply to Michele Blacksberg RN)

Thank you both, I was told to take antihistamines by my doctor but will go back!! Thank you, again.

July 14, 2014 - 8:34pm
(reply to Anonymous)

Sadly, you're probably just going to have to let it take its course. I suffered from this 2 years ago and I can remember how miserable I was like it was yesterday. Hot showers worked best for me. Good luck to ya!

July 14, 2014 - 6:34pm
EmpowHER Guest
Anonymous (reply to Leighandra Shenk)

Thank you. It just seems crazy that there isn't something that can be done to counteract it :( I've heard of it lasting up to 8 weeks!! How long until it cleared for you?

July 14, 2014 - 6:42pm
(reply to Anonymous)

It was about 14 days. . .I won't even eat shitake mushrooms cooked! Never again.

July 14, 2014 - 6:56pm
EmpowHER Guest

had the same thing. hot baths and ''CALAMINE'' LOTION helps a bit with the itchy sensation. it has a cooling and calming affect. be well.

June 16, 2014 - 6:29pm
EmpowHER Guest

I ate two of the mushrooms whist preparing them for a soup. Two days later I came out in a violent rash on my chest, neck, arms and body. It looked pimply and raised and red at first but later stripy, whip like marks appeared all over my abdomen, back bottom and upper thighs.
Anti histamines had little effect. The A&E gave me steroid tablets which helped to bring it down a bit. i still have the rash on my body but luckily it has subsided on my neck and chest. My hands were bad too, still sore and red itchy blotches on them. Never eating them again, knowingly!!

May 6, 2014 - 10:18am
EmpowHER Guest

Thank you! Finally an answer! The itchy scalp is driving me crazy! I plan to go back to the doctor and show her what I found. It doesn't sound as if there is any relief for this, other than to ride it out. I'm 7 days into this and the scratch-like rashes seem to be getting better.

December 14, 2013 - 10:12am
EmpowHER Guest

Thank you so much! I started having all these symtoms 2 days ago, that was 2 days after eatinggabout 5 or 6 slices of shiitake mushrooms (so it took very little to have this reaction). Itching and red rash are almost everywhere on my body. It iches a lot and i even have some marks in my face. I was given antihistamine but they don't work... I don't want to endure this for weeks :( oh well. Can't wait to return to normal!

December 5, 2013 - 12:18pm
EmpowHER Guest

No itch? Total BS. I am itching like crazy all over and yes, Shitake is the culprit. Itch is worse in scalp.

January 23, 2013 - 4:03pm
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We value and respect our HERWriters' experiences, but everyone is different. Many of our writers are speaking from personal experience, and what's worked for them may not work for you. Their articles are not a substitute for medical advice, although we hope you can gain knowledge from their insight.

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