Whether soaking fungus overnight is toxic or not depends on the specific condition of the fungus. If there has been obvious sticky or observed mold growth and so on, it is toxic and not recommended for consumption. The fungus in the water soaking time is long, it is easy to breed pathogenic microorganisms, there can be obvious sticky or observed mold growth and so on. Therefore, after soaking the fungus overnight, it is generally not recommended to eat again. But there are some special circumstances, such as in the cold winter, due to low temperature, mold is not easy to reproduce, this time overnight soaked fungus can generally be eaten. To sum up, soaked fungus after overnight whether toxic need to be judged on a case-by-case basis. In daily life soaked fungus should be eaten as soon as possible or put into the refrigerator for preservation. If there is any discomfort after consuming overnight soaked fungus, you should consult a doctor in time to avoid delaying your condition.