Playing closed needle is not very painful, and the general nurse intravenous infusion, shot, shot buttocks needle, or the needle is the same when the blood is collected intravenously, except that when playing closed, to inject the drug in the syringe into the painful parts, then there may be swelling, stinging and other discomfort, the key depends on the composition of the drugs used in closed needle and the amount of drugs used. Generally, the closed needle are to be combined with lidocaine and other anesthetic and pain medication together with the injection, the purpose is to reduce the pain or numbness and other discomfort caused by the drug filling. If you do not use anesthetics, simple anti-inflammatory and analgesic injection, there may be a tingling sensation, but generally this pain can be tolerated by normal people, no need to worry too much.