Dried shiitake mushrooms are moldy and cannot be eaten. The mold that causes dried shiitake mushrooms to become moldy is complex and can produce a variety of toxic substances, such as aflatoxin, with a bad odor. One accidental ingestion may cause digestive symptoms such as abdominal pain, diarrhea, nausea, vomiting, etc. If an excessive amount is ingested, it may lead to liver damage in serious cases. Therefore, if you accidentally consume moldy dried shiitake mushrooms and experience unpleasant symptoms, you need to seek medical attention immediately. Some people believe that if there is only surface mold on dried shiitake mushrooms and there is no obvious odor, they can be consumed by thoroughly washing and exposing them to the sun or baking them in the microwave oven, but some toxins are not easily destroyed, so for safety reasons, it is generally not recommended to consume them. The mold that can be observed by the naked eye is usually the most significant part of the deterioration, and the whole dried mushroom may contain toxins. Toxic aldehyde compounds may have been produced in all moldy foods, so good eating habits should be practiced and moldy foods should be thrown away promptly. It is recommended that when preserving dried shiitake mushrooms or other dried foods, they should be placed in a dry and ventilated place as much as possible, and can also be preserved by sealing them and keeping them at low temperature to avoid deterioration caused by moisture as much as possible.