You don’t have to get tetanus if you are cut by a knife. If the wound is shallow, you usually don’t need to get tetanus; if the wound is deep and there is serious active bleeding, it is better to get tetanus to prevent infection. 1. No tetanus: If the knife is not rusty and the cut is superficial and there is no active bleeding, tetanus can be avoided, but the wound should be sterilized repeatedly with iodophor cotton balls to prevent infection. 2. Tetanus: if the knife is rusty and the cut is deeper and there is active bleeding, it is best to play tetanus antitoxin or tetanus immunoglobulin within 24 hours of the cut to prevent tetanus infection. After being cut by a knife, you should go to the hospital in time, and the doctor will check the depth of the cut and treat it accordingly, and determine whether you need to take a tetanus shot, so as not to delay your condition.