What illness involves damage caused by one's immune system to its own tissues?

An autoimmune disease is characterized by the immune system mistakenly attacking the body's own healthy tissues. This inappropriate response can lead to inflammation, damage, and dysfunction of various organs and systems. In autoimmune diseases, the body's defenses become confused and target self-antigens, which are normally harmless to the body. Common examples of autoimmune diseases include rheumatoid arthritis, lupus, and multiple sclerosis.

In contrast, infectious diseases are caused by pathogens such as bacteria, viruses, or parasites; metabolic diseases involve disruptions in normal metabolic processes, which can affect how the body transforms food into energy; and degenerative diseases are conditions in which the function or structure of affected tissues or organs progressively deteriorates over time, often due to aging or wear and tear, rather than immune system activity. Understanding the distinction among these categories helps clarify the specific nature of autoimmune conditions.