Immunodeficiency refers to a condition in which the body's immune system fails to function properly. The immune system protects the body against bacterial and viral infections and toxins.

Primary immunodeficiency disorder is an immune deficiency that is not caused by medication or disease. Conditions linked to primary immunodeficiency include Job syndrome, Briton's disease, and combined immunodeficiency disease.

Secondary immunodeficiency disorders are caused by an existing medical condition or an environmental factor, such as radiation, chemotherapy, diabetes, or malnutrition. Diseases such as HIV/AIDS, leukemia and viral hepatitis are secondary immunodeficiency disorders. 

Symptoms of an immunodeficiency disorder include pinkeye, sinus infections, frequent colds, diarrhea, yeast infections, and pneumonia. 

Treatment of immunodeficiency depends on the underlying cause of the condition. Vaccines are often recommended to protect patients with immunodeficiency against infection. Drug classes commonly prescribed to treat immunodeficiency are immunoglobulins, normal human, and other disease-specific immunoglobulins. Antivirals and other treatments for infection may also be prescribed.