What Causes Autoimmune Diseases?

By Leah Campbell
Reviewed by Dana Cooper, M.D.
January 13, 2023

Autoimmune diseases affect more than 24 million people in the United States, according to the National Institutes of Health. And that rate may be rising, suggests a study published in April 2020 in Arthritis & Rheumatology.

Your immune system is supposed to be one of your body’s natural heroes. It’s meant to fight against illness and disease, attacking viruses and bacteria before they have the chance to take you down. But what happens when that immune system loses sight of what it should be attacking, and starts going after your own body instead? In these instances, it can feel like your immune system has morphed from hero to enemy.

What Are Autoimmune Diseases?

Autoimmune diseases are conditions that develop when the immune system “malfunctions” and becomes hyperactive, going after healthy tissues, cells, and organs. In general, autoimmune conditions happen when the immune system goes into overdrive making antibodies against certain antigens (proteins) in our body, causing our immune system to attack and damage that part of the body.