What Really Happens When You Eat Old Mushrooms

Since many wild mushrooms are poisonous, it's good practice to avoid eating any that you find growing in the forest or your yard. World Atlas says at least 30 wild-growing varieties are always fatal, and an additional 40 varieties can lead to severe illness. However, what you might not know is that even store-bought mushrooms can become dangerous if proper care isn't taken in their preparation.

Maybe you bought some white button mushrooms to sauté for a homemade pizza or some shiitake mushrooms to incorporate into a stir fry. Maybe you're saving some porcini mushrooms for a risotto or some of those massive Portobello mushrooms for a vegetarian-friendly burger.

Unfortunately, even these seemingly safe mushrooms can pose some health hazards. Some varieties are especially prone to soaking up moisture, which can make them go bad more quickly if they aren't stored properly. Although proper storage can keep mushrooms fresh longer, it isn't a permanent solution. 

When in doubt, throw it out

If you're reorganizing the fridge and you find a package of mushrooms you've forgotten about, toss them in the garbage. Even if they look okay, those old mushrooms might make you very sick. According to Consumer Health Digest, old mushrooms can lead to botulism, a rare but fatal condition. Symptoms include difficulty breathing, vomiting, and paralysis. Old mushrooms may also carry E. coli, especially if they were improperly cleaned or served raw. An E. coli infection can lead to abdominal pain, vomiting, and diarrhea. Fortunately, most people recover within a week with treatment, the CDC says.

A third possible outcome of eating old mushrooms is salmonella infection. This is highly influenced by your cooking method, but mushroom age can only make matters worse. It can take months for your digestive tract to return to normal.

To avoid getting sick from your mushrooms, keep track of how long they're in the fridge. Be sure to store them properly and safely. Delishably says throw mushrooms out if any become slimy, smelly, wrinkly, or darker in color. It's far better to be safe than sorry.