You can judge whether the pus has flowed cleanly by squeezing or flushing with hydrogen peroxide, the specific analysis is as follows: 1. squeeze: after the pustule is broken, you can gently squeeze the pustule, if there is no continued discharge of pus, only fresh blood outflow, indicating that the pus has flowed cleanly, and if it continues to flow pus, etc., indicating that it is not clean. 2. Hydrogen peroxide flushing: after the pus bag is broken, you can use hydrogen peroxide flushing, if no pus or yellowish-green pus is seen when flushing, the flushing liquid is relatively clean, indicating that the pus has flowed cleanly, and vice versa, it is not clean. It is not recommended that patients use the method of squeezing to determine whether the pus is clean or not, so as to avoid the presence of bacteria in the hand to lead to aggravation of the infection, and other adverse effects, it is recommended that patients seek medical treatment, under the operation of the doctor to confirm.