What Is an Autoimmune Disease?

A Group of 80 or More Diseases Caused by Immune System Malfunction

Woman talking to her doctor.
Stigur Karlsson/E+/Getty Images

Simply put, an autoimmune disease is associated with a malfunction of the immune system which causes the body to attack its own tissues. The body's immune system is a complex network of specialized cells and organs which defends against foreign substances and invaders. The foreign substances and invaders can include bacteria, parasites, some cancer cells, and transplant tissue. Normally, the body's immune system only reacts to foreign substances and invaders in order to protect the body.

Normal antibodies are proteins produced by the immune system to target foreign invaders.)

When the immune system malfunctions, the body mistakes its own tissues as foreign and it produces immune cells (lymphocytes) and autoantibodies that target and attack those tissues. The inappropriate response, which is referred to as an autoimmune reaction, can cause inflammation and tissue damage.  

Autoimmune Reaction

You may be wondering how an autoimmune reaction can occur. The autoimmune reaction may be triggered:

  • if a normal body substance is altered, such as by a virus or a drug, causing the body to recognize it as foreign.
  • if a foreign substance that is similar to a normal body substance enters the body.
  • if cells that control antibody production malfunction and produce abnormal antibodies that attack the body's own cells.
  • a typically localized substance in the body (i.e., body fluid) is released into the bloodstream, stimulating an abnormal immune reaction. This could be caused by an injury.

    Autoimmune Disease Is Not Uncommon

    There are more than 80 types of autoimmune diseases. Symptoms depend on which part of the body is affected. There are autoimmune disorders that target specific types of tissue (e.g., blood vessels, skin, or cartilage). Other autoimmune diseases may target a specific organ.

    Any organ can be involved. Characteristics which are typically associated with autoimmune disease include inflammation, pain, muscle aches, fatigue, and a low grade fever. Inflammation is usually the first sign of an autoimmune disease. 

    Autoimmune diseases affect more than 23.5 million Americans, according to womenshealth.gov. AARDA.org states that there are 50 million Americans living with an autoimmune disease, of whom 75% are women. While some autoimmune diseases are rare, a number of the conditions are common. Autoimmune diseases can affect anyone but it is believed that some people have a genetic predisposition for developing an autoimmune disease under certain circumstances (i.e., something acts as a trigger). People at greater risk for developing an autoimmune disease include:

    • women of childbearing age.
    • people who have a family history of autoimmune disease.
    • people who have certain environmental exposures that could act as the trigger.
    • people of a particular race or ethnicity.

    Many types of arthritis are considered autoimmune diseases, including:

    Other autoimmune diseases include alopecia areata, antiphospholipid antibody syndrome, autoimmune hepatitis, type 1 diabetes, Graves' disease, Guillain-Barre syndrome, Hashimoto's disease, hemolytic anemia, idiopathic thrombocytopenic purpura, inflammatory bowel disease, multiple sclerosis, myasthenia gravis, primary biliary cirrhosis, psoriasis, and vitiligo.

    Chronic fatigue syndrome and fibromyalgia are not considered autoimmune diseases. This has been a source of confusion since some symptoms of chronic fatigue and fibromyalgia overlap with several autoimmune diseases.

    It is the overlap of symptoms with other autoimmune diseases, as well as with diseases that are not autoimmune, that can make diagnosis an arduous process. According to AARDA.org, most autoimmune disease patients go more than 4 years and may see up to 5 doctors before they are properly diagnosed.

    Treatment of Autoimmune Disease

    Treatment of autoimmune disease focuses on controlling the autoimmune reaction with immunosuppressant medications. Corticosteroids may be used to control inflammation and suppress the immune system. Other medication options depend on the specific autoimmune disease. Biologic drugs, for example, are now commonly used to treat rheumatoid arthritis or other inflammatory types of arthritis


    Autoimmune Disease in Women. American Autoimmune Related Diseases Association. Accessed 10/24/15.

    Autoimmune Diseases Fact Sheet. Womenshealth.gov. July 16, 2012.

    Autoimmune Disorders. Merck Manuals. Peter J. Delves, Ph.D. Accessed 10/24/15.

    Continue Reading