Hairy crabs that have just died or are already dead cannot be eaten. This is because when a crab is dying or dead, the histoxic acid in the crab's body will decompose to produce histamine. Histamine is a toxic substance, with the prolongation of the death time, the crab body accumulates more and more histamine, more and more toxic, even if the crab is cooked, this toxin is not easy to be destroyed. And excessive ammonia nitrogen must be excreted from the kidneys, so eating dead hairy crabs is very bad for the kidneys. Symptoms such as vomiting, abdominal pain and diarrhea may occur in people who eat dead crabs.

Even half-dead crabs are not suitable for consumption. The infection rate and degree of infection of larval cysts of Schistosoma pneumoniae in live crabs are very high. Schistosoma pneumoniae parasites live in the lungs, irritating or destroying the lung tissues, causing coughing and even hemoptysis, and if they invade the brain, they can cause paralysis.

According to expert examination, the crab slightly heated after eating, schistosoma infection rate of 20%, eating pickled crab and drunken crab, schistosoma infection rate of up to 55%, while eating crab raw, schistosoma infection rate of up to 71%. The resistance of the Schistosoma cysticerci is very strong, and they are usually killed by soaking in 55℃ water for 30 minutes or pickling in 20% salt water for 48 hours.

Eating crabs raw may also trigger symptoms such as intestinal inflammation, edema and congestion. Therefore, eating steamed and cooked crabs is the most hygienic and safe. When steaming crabs, it is important to note that after the water is boiled, it should be boiled for at least another 20 minutes and cooked thoroughly before the crab meat germs can be killed. One thing is also very important to eat must be removed from the crab gills, crab heart, crab stomach, crab intestines four substances, because it contains bacteria, viruses, sludge, etc..