Lentinan is a polysaccharide extracted from Shiitake mushrooms and used as an adjuvant therapeutic drug in treating patients with lung cancer in China. Lentinan is mainly composed of β-glucan with anti-tumor, anti-inflammatory, anti-diabetes properties, and other therapeutic properties. Lentinan was approved as an adjuvant for stomach cancer therapy in Japan in 1985. It is approved for treating multiple types of cancer, hepatitis, and other diseases in China. Lentinan is available as capsules, tablets, and injections. The capsules and tablets of lentinan is taken orally as a traditional medicine. Intravenous injection of lentinan is clinically approved and used in hospital with a dose of 1–1.5 mg/day. Low blood pressure, allergy, urgent appeal, and dizziness were the major side effects.