Itchy and painful wound scars are a common symptom in patients after surgery and trauma. This is because after about 2~3 weeks of scarring, the scars start to proliferate with local redness, purple color and protrude out of the skin surface with newborn nerve endings in a disorganized manner. The scar tissue in the proliferation period is quite sensitive to the physical and chemical factors of the surrounding environment, so the scar will become itchy or painful when there is a change in the outside world, especially the itch is more obvious. For example, when sweating a lot, the sodium chloride, potassium chloride, protein and urea in the sweat stimulate the sensitive nerve endings in the scar, so it produces pain or strange itching; when the weather changes suddenly, because the temperature difference between hot and cold and the change of wet and dry is much stronger than usual, the nerve endings in the scar can sensitively perceive this change and tell people with itching and pain signals. This proliferative period lasts about 3.5 months or even a year. Later, the proliferation of fibrous tissue gradually stops, and the scar gradually flattens and softens, and its color changes to light brown or grayish white, at which point the scar enters the degenerative and atrophic phase (old scar), and the itching symptoms will gradually reduce or disappear. Therefore, it is a normal phenomenon to have prickly itch in the healed scar for a period of time, which is not a symptom of other lesions, and there is no need to be nervous so as not to increase the psychological burden.