What’s the Difference Between a Syndrome and a Disease?

The words "syndrome" and "disease" are often used interchangeably, but they have some important differences.

The classification, though, has no bearing on whether they're real illnesses or how serious they are. It's simply a matter of how well they're understood.

This article examines the differences between a syndrome and a disease and provides examples of both.

Doctor showing digital tablet to patient
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What Is a Syndrome?

The definition of a syndrome is pretty straightforward:

  • A collection of signs and symptoms known to frequently appear together that suggest the presence of a disease or an increased chance of developing one

In typical medical usage, a syndrome often doesn't have an understood cause, course, or underlying process. This generally means treatments are lacking and there's no known cure.

When doctors designate something a syndrome, they're essentially saying, "We recognize this cluster of symptoms but we don't yet know what's going on."

That doesn't mean the symptoms aren't real or aren't serious, it just means medical science hasn't yet determined why they're happening.

Common Syndromes

Examples of syndromes and their primary symptoms are:

  • Metabolic syndrome: Abnormalities in blood sugar, blood pressure, body fat, cholesterol, and triglycerides that are tied to the development of heart disease and type 2 diabetes
  • Fibromyalgia: Chronic widespread pain, extreme fatigue, cognitive dysfunction
  • Restless legs syndrome: Unusual sensations when the legs are at rest that are temporarily relieved by movement
  • Irritable bowel syndrome: Chronic digestive symptoms often tied to specific foods
  • Myofascial pain syndrome: Painful trigger points in muscles and connective tissues, often as a result of injuries
  • Vulvodynia: Chronic pain in the vulva (outer portion of the female genitalia) with no known cause
  • Interstitial cystitis: Also called painful bladder syndrome
  • Multiple chemical sensitivity: Abnormal reactions to small amounts of chemicals, especially those with strong odors

Many conditions start out as syndromes and are then re-classified as a disease once more is known about them. If the name of the illness contains the word syndrome, it may or may not be changed.

What Is a Disease?

The definition of disease is a little more complicated than that of syndrome. You can find several, incuding:

  • A disordered or incorrectly functioning organ, part, structure, or system of the body resulting from the effect of genetic or developmental errors, infection, poisons, nutritional deficiency or imbalance, toxicity, or unfavorable environmental factors
  • A definite pathological process having a characteristic set of signs and symptoms. It may affect the whole body or any of its parts and its etiology, pathology, and prognosis may be known or unknown

The second definition especially doesn't seem to do a good job of separating a disease from a syndrome. In common medical usage, though, a disease is generally considered to have:

  • A known cause
  • Clear symptoms
  • Accepted treatments

Common Diseases

Examples of disease and their causes are:

Changing Names

When researchers re-classify a syndrome as a disease, sometimes the name is changed and sometimes it's not. For example, AIDS is still in use even though the S stands for syndrome and it's now considered a disease. When names are changed, it can take time for the new name to gain widespread use.


A syndrome is a group of signs and symptoms that are known to go together but don't have a clear cause, course, or treatment path.

A disease is a disorder that affects how your body functions and is more likely to have a known cause, a distinct course, and established treatments.

If you're diagnosed with a syndrome, you may run into people who don't think it's serious or "real" because it's not a disease. This isn't the case. It really just means that medical science hasn't figured it out yet.

Frequently Asked Questions

  • What causes disease?

    Diseases can be caused by many things. In general, these include:

    • Infection: Viruses, bacteria, fungi, and parasites
    • Degeneration: Deterioration of cells and structures over time
    • Allergies: Developed hypersensitivity to substances
    • Deficiencies: Inadequate levels of hormones, minerals, nutrients, or vitamins
  • What causes syndromes?

    Syndromes are generally caused by the same things that cause diseases (see above). However, the cause of any particular syndrome isn't usually known.

  • What is a condition?

    Medically speaking, a condition is any disease, disorder, syndrome, or tissue abnormality. Some definitions of condition exclude mental disorders.

21 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. National Institutes of Health, National Cancer Institute. Syndrome.

  2. University of Utah: U Health. What exactly are syndromes?

  3. National Institutes of Health, U.S. National Library of Medicine: MedlinePlus. Metabolic syndrome.

  4. National Institutes of Health, U.S. National Library of Medicine: MedlinePlus. Fibromyalgia.

  5. National Institutes of Health, U.S. National Library of Medicine: MedlinePlus. Restless legs.

  6. National Institutes of Health, U.S. National Library of Medicine: MedlinePlus. Irritable bowel syndrome.

  7. Jafri MS. Mechanisms of myofascial pain. Int Sch Res Notices. 2014;523924. doi:10.1155/2014/523924

  8. National Vulvodynia Association. What is vulvodynia?

  9. National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases. Interstitial cystitis (painful bladder syndrome).

  10. Johns Hopkins Medicine. Multiple chemical sensitivity.

  11. Dictionary.com. Disease.

  12. The Free Dictionary by Farlex: Medical Dictionary. Disease.

  13. Centers for Disease Control and Prevention. Chickenpox (varicella).

  14. Centers for Disease Control and Prevention. Types of influenza viruses.

  15. Centers for Disease Control and Prevention. Cold versus flu.

  16. Centers for Disease Control and Prevention. About infectious mononucleosis.

  17. World Health Organization. Coronavirus disease (COVID-19).

  18. National Health Service. Causes: Parkinson's disease.

  19. National Institutes of Health, U.S. National Library of Medicine: MedlinePlus. Autoimmune disorders.

  20. National Institutes of Health, National Cancer Institute. What is cancer?

  21. Pallipedia. Medical condition.

By Adrienne Dellwo
Adrienne Dellwo is an experienced journalist who was diagnosed with fibromyalgia and has written extensively on the topic.