Internal cause: people with allergies encounter allergens. After eating crabs, some special substances in crabs will combine with human allergens and release histamine, thus the body will show allergic reactions.

External factors: There are many situations, which may be that the crab itself has safety problems. First, the crab comes from the sea, industrial and domestic sewage is discharged into the sea, the sea water is polluted, the crab lives in the sea, and harmful substances can easily invade the crab. Coupled with the freshness of crabs, allergies are likely to occur after eating crabs.

See: ipartment, Zhang Wei.