Cooked crabs can generally be eaten overnight if they are well preserved at low temperature and have not deteriorated, but if they are not properly preserved or even have an offensive odor, it is not advisable to eat them overnight in this case. For cooked crabs, it is recommended to wrap them in plastic wrap and then place them in the refrigerator for freezing, usually overnight and then reheat them at a high temperature the next day, but generally not more than the next day. However, if the cooked crab is placed in a pot or bowl without being frozen and in direct contact with the air, the surface or internal organs of the cooked crab or even the soup will easily breed bacteria and lead to spoilage, which may cause diarrhea, abdominal pain, vomiting and other gastrointestinal discomfort after eating overnight. Also, some cooked crabs contain chemicals such as histidine, which, under the influence of some microorganisms, may break down into histamine and histamine-like components, which may induce food poisoning when consumed in large quantities. For those who like to eat crabs, it is important to cook them at high temperatures and it is advisable to finish eating them the same day, preferably not more than 24 hours, to avoid affecting their taste and food safety. If you experience discomfort after eating crab, it is advisable to go to the hospital as soon as possible to clarify the cause and give targeted treatment.