Generally speaking, a tetanus shot needs to be administered intramuscularly, but a skin test must be conducted before injection because tetanus vaccines can easily cause allergic reactions. The skin test usually involves a subcutaneous injection on the palm side of the forearm, followed by an observation period of 15 to 20 minutes. If there is no redness or itching, and the skin test is negative, then the vaccine can be administered intramuscularly, usually in the buttock. However, if the skin test is positive, as indicated by symptoms like redness, significant itching, or even systemic symptoms such as dizziness and cold sweats, it shows that the skin test for tetanus is positive. In this case, one can opt for a desensitization injection of diluted tetanus vaccine, followed by intramuscular injections four times, once every half hour, needing about two hours to complete.