Print OverviewHypereosinophilic (hy-per-ee-o-SIN-o-phil-ik) syndrome (HES) is a group of blood disorders that occur when you have high numbers of eosinophils — white blood cells that play an important role in your immune system. Over time, the excess eosinophils enter various tissues, eventually damaging your organs. The most common targets are the skin, lungs, digestive tract, heart, blood and nervous system. Untreated, HES can become life-threatening.Products & ServicesA Book: Mayo Clinic Family Health BookNewsletter: Mayo Clinic Health Letter — Digital EditionShow more products from Mayo Clinic SymptomsEarly symptoms of HES may include fatigue, cough, breathlessness, muscle pain, rash and fever. CausesSome varieties of hypereosinophilic syndrome tend to run in families. Other types have been associated with certain types of cancers, infections or other health problems. Risk factorsHES can affect anyone. But it occurs more often in men, usually between the ages of 20 and 50. By Mayo Clinic Staff Hypereosinophilic syndrome care at Mayo Clinic Request an appointment Diagnosis & treatment April 27, 2022 Print Living with hypereosinophilic syndrome? Connect with others like you for support and answers to your questions in the Blood Cancers & Disorders support group on Mayo Clinic Connect, a patient community. Blood Cancers & Disorders Discussions Immune Thrombocytopenia Purpura (ITP): What helps? 168 Replies Wed, Dec 11, 2024 chevron-right Does anyone else have MGUS? 835 Replies Wed, Dec 11, 2024 chevron-right Anyone else find the side effects of Hydrea 500MG frightening? 140 Replies Tue, Dec 10, 2024 chevron-right See more discussions Show references Hoffman R, et al. Eosinophilia, eosinophil-associated diseases, eosinophilic leukemias, and the hypereosinophilic syndromes. In: Hematology: Basic Principles and Practice. 7th ed. Elsevier; 2018. https://www.clinicalkey.com. Accessed April 21, 2020. Eosinophil. NCI Dictionary of Cancer Terms. National Cancer Institute. https://www.cancer.gov/publications/dictionaries/cancer-terms/def/eosinophil. Accessed April 21, 2020. AskMayoExpert. Eosinophilia, hypereosinophilia, and hypereosinophilic syndrome. Mayo Clinic; 2019. Ferri FF. Hypereosinophilic syndrome. In: Ferri's Clinical Advisor 2020. Elsevier; 2020. https://www.clinicalkey.com. Accessed April 22, 2020. Roufosse F, et al. Hypereosinophilic syndromes: Clinical manifestations, pathophysiology and diagnosis. https://www.uptodate.com/contents/search. Accessed April 22, 2020. Roufosse F, et al. Hypereosinophilic syndromes: Treatment. https://www.uptodate.com/contents/search. Accessed April 22, 2020. Morrow ES Jr. Allscripts EPSi. Mayo Clinic. Feb. 10, 2020. Related Products & Services A Book: Mayo Clinic Family Health Book Newsletter: Mayo Clinic Health Letter — Digital Edition Show more products and services from Mayo Clinic Hypereosinophilic syndromeSymptoms&causesDiagnosis&treatmentDoctors&departmentsCare atMayoClinic Advertisement Mayo Clinic does not endorse companies or products. Advertising revenue supports our not-for-profit mission. Advertising & Sponsorship Policy Opportunities Ad Choices Mayo Clinic Press Check out these best-sellers and special offers on books and newsletters from Mayo Clinic Press. NEW: Listen to Health Matters Podcast - Mayo Clinic PressNEW: Listen to Health Matters PodcastMayo Clinic on Incontinence - Mayo Clinic PressMayo Clinic on IncontinenceThe Essential Diabetes Book - Mayo Clinic PressThe Essential Diabetes BookMayo Clinic on Hearing and Balance - Mayo Clinic PressMayo Clinic on Hearing and BalanceFREE Mayo Clinic Diet Assessment - Mayo Clinic PressFREE Mayo Clinic Diet AssessmentMayo Clinic Health Letter - FREE book - Mayo Clinic PressMayo Clinic Health Letter - FREE book CON-20306102 Patient Care & Health Information Diseases & Conditions Hypereosinophilic syndrome