Why Am I Suddenly Allergic to Mushrooms?

As I get older, I seem to be developing more food allergies. Not typical food allergies, though, like peanuts or dairy. It's more obscure foods like figs and, most recently, shiitake mushrooms. How I learned about the new mushroom allergy was accidental and unpleasant.

Discovering a new mushroom snack

Recently over the weekend, I went to visit my parents. They served a beautiful charcuterie board filled with cheese, crackers, and Italian meats. The spread also included a snack I had not seen before, dehydrated mushrooms.

I popped a dehydrated mushroom in my mouth, and I was hooked! They were delicious—crunchy, salty, and full of mushroom flavor. FYI, I love, love, love all mushrooms, raw, cooked, and served in all kinds of ways. Every week I go to the local farmer's market and purchase different varieties. I typically use mushrooms in my homemade soups and salads. I have cooked and eaten shiitake mushrooms several times without incident.

An unintended long drive back home

The weekend ended, and the next day I packed up to head back home, which was about a 3-hour drive. My parents, being parents, packed up a to-go bag for me filled with all sorts of goodies, including an unopened, large bag of dehydrated shiitake mushrooms.

Along my commute, the 3-hour drive turned into a 6-hour trip, thanks to traffic on the interstate. I was hungry but didn't want to get off the highway to grab a meal for fear I wouldn't be able to get back onto the road.

"No big deal," I thought, "I have an entire goody bag full of snacks!" I couldn't wait to dive into the bag of mushroom snacks, so I ripped it open and grabbed a few. A few turned into a couple more. And then even more.

After sitting in traffic for so long, I somehow managed to eat the entire bag of dehydrated mushrooms (don't judge)! I was bored, hungry, and frustrated from being stuck in traffic, and I just mindlessly ate the bag.

Having a new and different allergic reaction

The following day, I woke up with an itchy chest. I had weird-looking marks on my skin. It itched like a rash but didn't look like a rash. It looked more like someone had scratched me.

I thought, "that's weird," but then didn't think much else about it. The next day, the rash expanded to my back and torso. And the following day, to my thighs and arms. The itching became uncontrollable, and my body looked like someone had slashed it with a knife. I decided it was time to book a telehealth appointment with my doctor.

Being diagnosed with shiitake flagellate dermatitis

During our video visit, I showed the doctor my rash, and she asked the usual allergy questions. "Have you eaten anything new or used different personal care products?" I embarrassedly admitted that I ate a lot of the dehydrated mushrooms.

She smiled and said the rash was more than likely something called "shiitake flagellate dermatitis" – an allergic reaction that very few people get from eating raw or undercooked mushrooms.¹

She recommended I take an antihistamine and use a steroid cream on the rash. My doctor assured me that the rash would clear up quickly. Luckily, it cleared up in a few days and did not leave any scars.

It was so disappointing to find out I'm allergic to a food I enjoy so much.

How about you? Have you been diagnosed with an allergy to a food you have eaten before without any reaction? Share with us in the comments below.