For allergies after eating crabs, patients can choose different medications according to the different allergy symptoms, and in critical cases, other medical assistance is needed for treatment. In mild allergic reactions, such as mild nausea, vomiting, abdominal pain, diarrhea and other gastrointestinal symptoms, oral antihistamines, such as cetirizine, chlorpheniramine maleate, loratadine, etc., can be taken under the premise of stopping eating to relieve allergic reactions, and anti-diarrheal and anti-emetic drugs such as montelukast and metoclopramide hydrochloride can also be taken to accelerate the excretion of allergic substances and reduce symptoms. In severe allergic reactions, which may manifest as a sharp drop in blood pressure, respiratory distress, loss of consciousness or anaphylactic shock, food should be stopped immediately and fasting should be administered, and anti-allergic and anti-shock treatments such as epinephrine and glucocorticoid infusion should be applied promptly. Patients who are allergic to crabs need to be more alert when eating other seafood and can have allergen tests.