Black fungus cooked overnight can be eaten if there is no sign of deterioration, but cooked black fungus may deteriorate during storage and consumption of deteriorated black fungus may cause adverse effects on the body and even toxic reactions. Moreover, black fungus after deterioration cannot generally be judged simply by its appearance to determine whether it harbors bacteria, so to avoid this risk, you should try not to eat black fungus cooked overnight. Cooked food left overnight is prone to breeding pathogenic bacteria, which may produce symptoms of acute gastroenteritis such as abdominal pain and diarrhea after consumption, or may cause severe toxic reactions such as dizziness, palpitations, vomiting, etc. after consumption. If occasionally black fungus is cooked and needs to be left overnight, filter the water out of the fungus and try to store it in the refrigerator under airtight refrigeration to reduce the risk of deterioration. However, care needs to be taken to avoid storing the food for too long. Even if the food is stored in the refrigerator for too long, it may be harmful to the human body. The food safety risk of overnight food may be relatively higher compared to freshly cooked food. It is recommended to consume fresh food as much as possible in daily life. Overnight food, even if it has not deteriorated, will have a reduced taste and nutrient content to some extent. Apart from black fungus, other ingredients should also be stored under clean and fresh conditions to ensure freshness of ingredients for good health.