An autoimmune disease occurs when the immune system mistakenly attacks the body's own cells. Some potential triggers are microorganisms, drugs, or genetic factors. Common autoimmune diseases include Graves' disease, rheumatoid arthritis, thyroiditis, type 1 diabetes, and multiple sclerosis. Symptoms can vary widely but include fatigue, rashes, pain, and organ damage. Diagnosis involves blood tests and examinations. Treatment options include medications that suppress the immune system. Lifestyle and dietary changes may also help manage autoimmune conditions.