Autoimmune Disease
A condition in which the immune system mistakenly attacks the body's own tissues.
Definition
An autoimmune disease develops when the immune system, which normally defends the body against infection, mistakenly targets healthy cells and tissues. There are more than 80 recognized autoimmune diseases, ranging from organ-specific conditions to systemic disorders. The causes involve a combination of genetic susceptibility and environmental triggers.
The Diagnostic Journey
A typical path patients take with Autoimmune Disease — from first symptoms to living with the condition. Click each stage to expand.
Many invisible illnesses begin with vague, intermittent symptoms such as fatigue, pain, or changes in weight or mood. Because these signs are non-specific and can come and go, they are frequently attributed to stress or overwork, which is one reason diagnosis is so often delayed.
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Related Glossary Terms
Sources & References
This page draws on trusted, authoritative health resources. For medical decisions, always consult a qualified healthcare professional.
- Autoimmune DiseasesNational Institute of Allergy and Infectious Diseases (NIAID), NIHGovernment Health Agency
- Diseases & ConditionsAmerican College of RheumatologyProfessional Medical Society
- Patient Engagement & Hormone HealthEndocrine SocietyProfessional Medical Society
- Health InformationNational Institutes of Health (NIH)Government Health Agency
- Health Topics: Trusted Consumer Health InformationMedlinePlus, U.S. National Library of MedicineGovernment Health Agency
- Health Topics A-ZMedlinePlus, U.S. National Library of MedicineGovernment Health Agency
- Health Library: Diseases & ConditionsCleveland ClinicAcademic Medical Center
Content Review
- Last Reviewed
- July 2026
- Last Updated
- July 2026
- Content Type
- Educational Documentary Companion
- Evidence Standard
- Evidence-Informed
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