The efficacy of Psidium guajava is to clear the lungs, dissolve phlegm, and benefit the qi and the chest (to smooth the flow of qi). It is cold in nature, sweet in taste, and mainly goes to the lung and stomach meridians. It has the efficacy of clearing lungs and resolving phlegm (clearing lung heat), inducing qi and relaxing the chest, and is mainly used in the treatment of coughing with phlegm due to lung heat, tightness in the chest, distension and pain in the chest and ribs, swelling and pain in the throat, carbuncle in the breasts (the main symptom of which is the breasts are red, swollen and painful with the breasts not flowing well and pus forming into carbuncle), and lactation fetish (the clinical characteristics of which are mainly pain in the breast and lumps), and so on. It should be noted that, according to the Chinese medicine principle of eighteen anti-drugs, Psidium guajava should not be used with Chuanwu, Caowu, appendicitis and its products, so as to avoid toxic side effects. And weak spleen and stomach, phlegm and dampness coagulation people should not use piper betel. In addition, the specific medication principles of piper betel should be taken under the guidance of a professional physician.