What we usually call serum disease belongs to type III hypersensitivity reaction, this disease is used in the early days after the animal immunization, especially the horse immunized serum to treat diseases such as diphtheria, tetanus. With the development of science, the birth of antibiotics, this type of disease does not need to be treated with this immune serum, we can achieve prevention through immunization. However, the causes of type III hypersensitivity reactions mainly include drug-related factors, the most common of which are penicillin, pioneer antibiotics, and the antihyperthyroid drug propylthiouracil, all of which can lead to type III hypersensitivity reactions. In addition, there are some foods, including some patients are allergic to xenobiotics, such as crab and shrimp, which can also trigger hypersensitivity reactions. There is also the snake venom antiserum injected after the snake bite, which can also cause type III hypersensitivity reactions.