Whether a finger cut by a knife needs a tetanus shot must be determined by the depth of the wound and the degree of contamination. If the wound is not very deep after being cut by a knife, and the knife is relatively clean, and the wound is not obviously contaminated, etc., a tetanus shot is usually not needed, and the wound can heal gradually with proper disinfection, bandaging and bleeding stoppage. If the wound is cut deeper and bleeds more, and the knife is rusty, or the wound is contaminated by surrounding objects, in this case tetanus antitoxin must be injected to prevent the infection of tetanus bacillus. A skin test is done before any tetanus injection, and allergies are ruled out before an intramuscular injection can be given.