How long it takes to rule out the danger after a crab stuck in the hand cannot be generalized and needs to be judged in relation to the severity of the damage caused. In general, if a crab has caught your hand, you should go to the emergency department or general surgery department in a timely manner if the trauma is large. Depending on the severity of the trauma, different treatment methods are required. If there is no skin laceration after being caught, only local redness, swelling and pain, cold compresses can be applied within 48 hours to avoid aggravation of swelling, and normal recovery is usually possible in about 3-5 days. If there is a skin fracture, the wound needs to be cleaned and sutured, regular drug changes, oral antibiotics to prevent infection, generally about 2 weeks to heal the wound and remove the stitches. If a finger bone fracture occurs, external fixation with a splint or internal fixation with a small plate is required, and it takes 6-8 weeks to recover. In addition, patients bleeding from crab lacerations need tetanus vaccination or tetanus antitoxin injection. The incubation period of tetanus is about 1 week after the trauma, and the chance of tetanus infection decreases after 1 week.