The angle of the intradermal injection requires the syringe needle to be at a 5-degree angle to the skin, with the bevel of the needle directed upward into the patient’s dermis, not into the patient’s subcutaneous tissue. It is used for skin testing, i.e., skin sensitization testing, or prophylactic inoculation, as well as during local anesthesia. Prior to intradermal injection, the skin surface should be intact, i.e., free of redness, swelling, nodules and scars. Then the skin surface is sterilized twice with alcohol or iodine povidone, and usually 0.1 ml of liquid is injected intradermally, and after the injection is finished, the needle is removed quickly, and the local area should not be pressed.