Transfer factor injections are immune agents that boost the body’s immunity and assist the immune cells to do their job. Transfer factor injection is commonly used clinically to treat viral or mycobacterial infections, such as herpes zoster, epidemic encephalitis B, viral myocarditis and so on. It can also be used to treat immunodeficiency diseases, such as eczema, thrombocytopenia, etc. It can also be used as an adjuvant treatment for malignant tumors, such as lung cancer, nasopharyngeal carcinoma and breast cancer. Injectable transfer factor is usually injected subcutaneously to the inner upper arm or the lower inguinal end of the inner thigh where lymphatic return is more abundant, and can also be injected subcutaneously at the deltoid muscle of the upper arm. The drug is contraindicated in people who are allergic to it. It is recommended to use the drug under the guidance of a doctor and pay attention to possible allergic reactions such as rash, itchy skin, fever, etc. that may occur during the use of the drug, which need to be discontinued immediately and promptly seek medical treatment.