The concentration of penicillin skin test solution is 500 units of penicillin per 1 ml, and 0.05~0.1 ml is injected intradermally. In the long-term clinical trials, no matter from the safety, sensitivity, pain feeling and skin test results and other aspects of the comparative judgment, found that the best concentration of penicillin skin test solution for 500 units / ml, the general volume of each injection of the dermal mound of 0.05 ~ 0.1 ml ml, after 20 minutes, observation of the results of the skin test. If the patient has a positive reaction (patients with allergic reactions as the main manifestation, such as skin test localized dermatomes bulging, the appearance of redness, hard lumps, etc.) is prohibited; it should be noted that after three days of discontinuing penicillin, if you need to use the drug again, you need to carry out the skin test again. This kind of professional operation is carried out by doctors, and should not be operated blindly by oneself, so as not to cause harm to the body.