What You Should Know Before Eating Raw Shiitake Mushrooms

A staple of East Asian cuisine, shiitake mushrooms are a delicious addition to many dishes, from hearty bowls of ramen to comforting ginger chicken jook. While shiitakes seem like any other mushroom you'd find at your local market, eating them raw can have a surprising side effect: shiitake flagellate dermatitis. 

Although it affects only around 2% of people who eat the mushrooms undercooked or raw, shiitake flagellate dermatitis is a distinctive rash that typically appears 24 to 48 hours after consumption. It appears as itchy, bright red, lash-like marks across the body, typically on the back, chest, or abdomen, but in some cases, it can occur across limbs too. Along with the rash, some people experience additional symptoms, such as localized swelling, fever, diarrhea, tingling, and discomfort while swallowing. Shiitake flagellate dermatitis is caused by a reaction to lentinan, a polysaccharide with anti-inflammatory and antioxidant properties found in shiitake mushrooms. However, some individuals are sensitive to lentinan and have a toxic reaction to it, which is thought to be caused by the lentinan dilating blood vessels and releasing irritative compounds below the skin. 

Typically, shiitake flagellate dermatitis clears up for most people within a few weeks, and it's usually treated with antihistamines and corticosteroid creams. Fortunately, lentinan breaks down when exposed to heat, so even those sensitive to it can consume shiitake mushrooms so long as they are appropriately cooked. 

Because the lentinan in shiitake mushrooms breaks down when exposed to heat, cooking your mushrooms properly is essential to avoid a potential reaction. Even though shiitake flagellate dermatitis is relatively rare, it's still something that's better to avoid. Moreover, even if you've eaten raw shiitakes before, in large amounts, they can cause a reaction even in those who were previously unaffected. 

To properly break down lentinan, shiitake mushrooms should be cooked for between five and seven minutes and reach a temperature between 266 and 293 degrees Fahrenheit. If you want to ensure your mushrooms are done, use something like the Alpha Grillers Instant Read Meat Thermometer. Instant read thermometers are great for checking the temperature of mushrooms because you don't have to sit there and wait for the needle to move, and you can immediately know whether or not it's time to chow down. 

Now, you can use uncooked shiitakes in something like the filling for your own homemade spring rolls, so long as they can reach the temperature needed during cooking for the lentinan to deteriorate. Similarly, if you're making say a shrimp and eggplant stir fry with them, it's best to saute the shiitake mushrooms first to the optimal temp and add them back at the end.