A MAN had to go to A&E with an agonising rash because he ate a common mushroom.
The 72-year-old, from Switzerland, was left with a “streaky”, whip-like pattern across his back after eating shiitake mushrooms.
A man had to go to A&E with an agonising rash because he ate a common mushroom
The itchy rash — which extended over his buttocks — appeared two days before he was admitted and made it difficult for him to sleep.
Doctors diagnosed him with shiitake dermatitis, a reaction to the food.
Dr Egle Janusonyte, of Geneva University Hospitals, said: “Shiitake dermatitis occurs after consumption of raw or undercooked shiitake mushrooms.
“The characteristic streaky rash is also known as flagellate erythema.”
Shiitake dermatitis is a distinctive rash that can occur if you don’t cook the mushrooms properly.
It causes itchy, red lines to appear on your back that look like whip marks, which is why doctors call it “flagellate”.
The rash only occurs in around two per cent of people that eat raw or uncooked shiitake mushrooms.
It is a toxic reaction to lentinan, a carbohydrate found in the fungi, which activates an immune response.
Reactions usually occur between a few hours and five days after eating the mushrooms and affect the back and torso, although they can happen on the arms, legs and face as well.
Rashes normally disappear after a few weeks but patients can be given anti-inflammatory drugs to reduce the swelling.
The man’s case was first reported in The New England Journal of Medicine.
His rash occurred two days after eating a meal containing the mushrooms.
After doctors ruled out viral or bacterial infections, he was given glucocorticoids and oral antihistamines to reduce the symptoms.
Dr Janusonyte said: “The patient was reassured about the self-limited nature of the condition and was advised to fully cook shiitake mushrooms in the future.”
Doctors recommend you heat the mushrooms at more than 145C to ensure they are properly cooked.
After two weeks, the rash’s itchiness had reduced but there were still red patches on his back, doctors said.