An early popular folk therapy for patients with lung disease. In its legal system, copper coins and other substances dipped in water or oil scrape the patient's chest, back and neck, making the skin purple and congested locally to alleviate internal inflammation and pain.

Scraping is guided by the theory of meridians and acupoints in traditional Chinese medicine. By using special scraping instruments and corresponding techniques, dipping in a certain medium and scraping repeatedly on the body surface, red millet or dark red bleeding spots appear locally on the skin, thus achieving the effect of promoting blood circulation and suppurating. Because it is simple, convenient, cheap and efficient, it is widely used in clinic and is suitable for medical treatment and family health care. It can also be used in combination with acupuncture, cupping, pricking collaterals and bloodletting, so as to strengthen the efficacy of promoting blood circulation, removing blood stasis, eliminating pathogenic factors and expelling toxin.