An autoimmune disease occurs when
attacks and destroys healthy body tissue by mistake. There are more than 80 autoimmune diseases.
The blood cells in the body's immune system help protect against harmful substances. Examples include bacteria, viruses,
,
cells, and blood and tissue from outside the body. These substances contain antigens. The immune system produces
against these antigens that enable it to destroy these harmful substances.
When you have an autoimmune disease, your immune system does not distinguish between healthy tissue and potentially harmful antigens. As a result, your body sets off a reaction that damages or destroys normal tissues.
The exact cause of autoimmune diseases is unknown. One theory is that some microorganisms (such as bacteria or viruses) or medicines may trigger changes that confuse the immune system. This may happen more often in people who have genes that make them more prone to autoimmune diseases.
An autoimmune disease may result in:
The destruction of body tissue
Abnormal growth of an organ
Changes in organ function
An autoimmune disease may affect one or more organ or tissue types. Areas often affected by autoimmune diseases include:
Blood vessels
Connective tissues
glands such as the thyroid or pancreas
Joints
Muscles
Red blood cells
Skin
A person may have more than one autoimmune disease at the same time. Common autoimmune diseases include:
(gluten-sensitive enteropathy)
Inflammatory bowel disease (
,
)
(lupus)
The goals of treatment are to:
Control the autoimmune process
Maintain your body's ability to fight disease
Reduce symptoms
Treatments will depend on your disease and symptoms. Types of treatments include:
Supplements to replace a substance that the body lacks, such as thyroid hormone, vitamin B12, or insulin, due to the autoimmune disease
Blood transfusions if blood is affected
Physical therapy to help with movement if the bones, joints, or muscles are affected
Many people take medicines to reduce the immune system's abnormal response. These are called immunosuppressive medicines. Examples include corticosteroids (such as prednisone) and nonsteroid medicines such as azathioprine, cyclophosphamide, mycophenolate, sirolimus, or tacrolimus. Targeted medicines such as tumor necrosis factor (TNF) blockers and Interleukin inhibitors can be used for some diseases.
The outcome depends on the disease. Most autoimmune diseases are
, but many can be controlled with treatment.
Symptoms of autoimmune diseases can come and go. When symptoms get worse, it is called a flare-up.
Complications depend on the disease. Medicines used to suppress the immune system can cause severe side effects, such as higher risk for infections.
Contact your provider if you develop symptoms of an autoimmune disease.
There is no known prevention for most autoimmune disorders.
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Buckland M, Thaventhiran JE. Immunity. In: Randall D, Booth J, Wiles M, eds. Kumar and Clarke's Clinical Medicine. 11th ed. Philadelphia, PA: Elsevier Limited; 2026:chap 6.
Kono DH, Peterson EJ, Theofilopoulos AN. Immune tolerance and autoimmunity. In: Firestein GS, McInnes IB, Koretzky GA, Mikuls TR, Neogi T, O'Dell JR, eds. Firestein & Kelley's Textbook of Rheumatology. 12th ed. Philadelphia, PA: Elsevier; 2025:chap 21.
Updated by: Jacob Berman, MD, MPH, Clinical Assistant Professor of Medicine, Division of General Internal Medicine, University of Washington School of Medicine, Seattle, WA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.