It is not recommended to eat crab, shrimp and other seafood after taking cephalosporin, especially if there is a past history of allergic diseases, such as bronchial asthma, allergic rhinitis or skin allergies such as urticaria. If there is a history of the above-mentioned diseases, consider that the patient is allergic, so when applying cephalosporin, it is easy to cause allergic reaction itself, plus eating crab, shrimp and other allergy-prone foods, it is more likely to induce an allergic reaction attack. Therefore, if the rash appears during this period is not easy to determine whether it is caused by food or cephalosporin antibiotics, it is easy to delay the disease and make the drug forced to stop, affecting the treatment of the disease. Therefore, patients with allergies should try not to eat seafood after applying cephalosporin.