Tetanus allergy refers to the body not being allergic to tetanus antitoxin, which can be directly diluted with saline and then administered intramuscularly into the buttocks or upper arm. Alternatively, tetanus immunoglobulin, which does not require a skin test, can also be administered intramuscularly. The purpose of the tetanus shot is to prevent infection by the tetanus bacillus, an anaerobic bacterium. In deep wounds in an anaerobic environment, or in heavily contaminated wounds with dirt or rust, there is a high risk of colonization by tetanus bacilli in the human body, requiring tetanus vaccination treatment.