Coriolus mushroom is a fungus. People have used the fruiting body and other parts as folk medicine for a long time. Recently, researchers have started to isolate and identify substances in coriolus that might act like pharmaceutical drugs. Two of these substances are polysaccharide peptide (PSP) and polysaccharide krestin (PSK). Scientists think these chemicals might be able to fight cancer and boost the immune system. Coriolus mushroom, PSP, and PSK are used for stimulating the immune system; treating herpes, chronic fatigue syndrome (CFS), hepatitis, and pulmonary disorders; reducing phlegm; improving bodybuilding results; increasing energy; curing ringworm and a skin condition called impetigo; treating upper respiratory, urinary, and digestive tract infections; curing liver disorders including hepatitis; reducing the toxic effects and pain of chemotherapy and radiation therapy; increasing the effectiveness of chemotherapy; prolonging life and raising the quality of life of cancer patients; and increasing appetite.