The dark color of the affected area of potassium permanganate is mainly caused by local skin oxidation, and the factor of high local concentration cannot be excluded. Potassium permanganate belongs to strong oxidizing agent, the color is usually pink or mauve, and is mainly used for inflammation of the reproductive system, such as glansitis, vaginitis and so on. Because of the oxidizing effect of potassium permanganate on the local skin, it will cause the dark color of the affected area; in addition, if the concentration of potassium permanganate is not uniform, and the concentration in the affected area is relatively high, it can also cause the dark color of the affected area. The above situation is a normal phenomenon and there is no need to worry too much. Potassium permanganate is generally more concentrated and needs to be mixed according to a certain ratio, and should be used under the guidance of a doctor; if any abnormality occurs, you need to communicate with your doctor in time.