If a patient is injured and the injury is relatively deep, it is recommended to visit the hospital to receive a tetanus antitoxin injection to prevent tetanus infection. Before injecting the tetanus antitoxin, a skin test must be conducted to prevent allergic reactions, including severe complications such as anaphylactic shock. A common method for the skin test is to dilute 0.1ml of tetanus antitoxin in 0.9ml of saline to make a solution and take 0.05ml of it for a skin prick test on the forearm. The observation time for this test is generally 30 minutes, to monitor for any positive reactions at the site of the test.