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PubMed This is a summary of 23 peer-reviewed journal articles Updated
Hematology

How HES Affects Your Body: Symptoms and Warning Signs

At a Glance

Hypereosinophilic Syndrome (HES) is a multisystem disorder where excess eosinophils release toxic proteins that damage healthy organs. It commonly affects the heart, increases the risk of dangerous blood clots, and causes skin, lung, and digestive issues.

Hypereosinophilic Syndrome (HES) is often called a “multisystem” disorder because it can affect almost any part of the body. The symptoms you feel are not random; they are the direct result of eosinophils (a type of white blood cell) releasing toxic proteins into your tissues [1][2].

How Eosinophils Cause Damage

Eosinophils contain small sacs called granules. These granules hold powerful proteins, such as Major Basic Protein (MBP) and Eosinophil Cationic Protein (ECP) [3][4]. While these proteins are designed to kill parasites, in HES, they are released into healthy organs, causing:

  • Inflammation: Swelling and irritation of the tissue [5].
  • Necrosis: Actual death of the cells in the organ [6].
  • Fibrosis: The formation of permanent scar tissue that prevents the organ from working correctly [7].

The Heart: Löffler Endocarditis

The heart is one of the most critical organs affected by HES. This specific type of heart involvement is known as Löffler endocarditis [7]. It typically moves through three stages:

  1. Acute Stage: Eosinophils flood the heart muscle, causing hidden inflammation and swelling (edema) [6].
  2. Thrombotic Stage: Large blood clots (mural thrombi) form inside the heart chambers. These can break off and travel to the brain or other organs [8][9].
  3. Fibrotic Stage: The heart muscle becomes scarred and stiff, making it difficult for the heart to pump blood effectively. This is known as restrictive cardiomyopathy [7][10].

Neurological and Blood Clot Risks

HES creates a hypercoagulable state, meaning your blood is much more likely to clot than normal [11].

  • Thromboembolic Events: Clots can form in the deep veins of the legs (Deep Vein Thrombosis or DVT) or travel to the lungs (Pulmonary Embolism or PE) [12][13].
  • Neurological Issues: Clots from the heart or blood vessels can cause a stroke [14]. Patients may also experience encephalopathy (confusion or altered mental state) or peripheral neuropathy (numbness, tingling, or “pins and needles” in the hands and feet) [15][16].

Skin, Lungs, and Digestion

  • Skin: You may notice itchy rashes, painful oral or genital ulcers, or raised plaques [17][18].
  • Lungs: HES can cause a persistent cough, shortness of breath during exercise, and inflammation in the airways [19][20].
  • GI Tract: Symptoms include chronic diarrhea, abdominal pain, or colitis (inflammation of the colon) [21][22].

Warning Signs of a Medical Emergency

If you experience any of the following, seek immediate medical attention:

  • Stroke Signs (Remember FAST): Face drooping, Arm weakness, Speech difficulty, Time to call emergency services [14].
  • Heart Failure/PE Signs: Sudden, severe shortness of breath, chest pain, or rapid swelling in the legs [23][20].
  • Neurological Crisis: Sudden, severe confusion or a loss of consciousness [15].

Common questions in this guide

How does HES cause damage to my body?
In HES, a type of white blood cell called eosinophils releases toxic proteins into your healthy tissues. This causes swelling, cell death, and permanent scarring that can prevent your organs from working correctly.
What is Löffler endocarditis?
Löffler endocarditis is a serious heart condition caused by HES where eosinophils flood the heart muscle. It progresses from hidden inflammation to the formation of blood clots, and eventually leads to permanent scarring that makes it hard for the heart to pump blood.
Does HES increase my risk of blood clots?
Yes, HES creates a state where your blood clots much more easily than normal. These clots can form in your legs, travel to your lungs, or go to your brain, which increases the risk of a stroke.
What are the neurological symptoms of HES?
Neurological symptoms can include confusion, altered mental states, or peripheral neuropathy, which feels like numbness, tingling, or "pins and needles" in your hands and feet.
When should I seek emergency medical help for HES symptoms?
You should seek immediate medical attention if you experience signs of a stroke (like face drooping or speech difficulty), sudden severe shortness of breath, sudden chest pain, or rapid swelling in the legs.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Based on my eosinophil levels, what is my current risk for Löffler endocarditis?
  2. 2.Should I have a baseline Cardiac MRI or Echocardiogram to check for early heart muscle inflammation?
  3. 3.How can I distinguish between a 'normal' HES symptom and a medical emergency?
  4. 4.Are my current 'brain fog' or tingling sensations related to neurological HES involvement?
  5. 5.Do my current blood markers (like troponin) suggest any active heart strain?

Questions For You

Tap a prompt to share your answer — we'll use it plus this page's context to start a tailored conversation.

References

References (23)
  1. 1

    Hypereosinophilic syndrome: approach to treatment in the era of precision medicine.

    Klion A

    Hematology. American Society of Hematology. Education Program 2018; (2018(1)):326-331 doi:10.1182/asheducation-2018.1.326.

    PMID: 30504328
  2. 2

    Identification of a gain-of-function STAT3 mutation (p.Y640F) in lymphocytic variant hypereosinophilic syndrome.

    Walker S, Wang C, Walradt T, et al.

    Blood 2016; (127(7)):948-51 doi:10.1182/blood-2015-06-654277.

    PMID: 26702067
  3. 3

    Serum Levels of Eosinophil-derived Neurotoxin in Patients with Chronic Urticaria.

    Saleh AA, Al-Obaidi AM, Behiry EG, Hamed AM

    The Journal of clinical and aesthetic dermatology 2020; (13(9)):21-23.

    PMID: 33133337
  4. 4

    Eosinophilic biomarkers for detection of acute exacerbation of chronic obstructive pulmonary disease with or without pulmonary embolism.

    Yang QF, Lu TT, Shu CM, et al.

    Experimental and therapeutic medicine 2017; (14(4)):3198-3206 doi:10.3892/etm.2017.4876.

    PMID: 28912870
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    Non-invasive biomarkers to diagnose and monitor eosinophilic esophagitis: a systematic review.

    Noble SL, Tyrrell R, Mules TC, Inns S

    Frontiers in medicine 2025; (12()):1607306 doi:10.3389/fmed.2025.1607306.

    PMID: 40641963
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    Hypereosinophilic syndrome: considerations for the cardiologist.

    Bondue A, Carpentier C, Roufosse F

    Heart (British Cardiac Society) 2022; (108(3)):164-171 doi:10.1136/heartjnl-2020-317202.

    PMID: 34172539
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    Loeffler endocarditis as a rare cause of heart failure with preserved ejection fraction: A case report and review of literature.

    Gao M, Zhang W, Zhao W, et al.

    Medicine 2018; (97(11)):e0079 doi:10.1097/MD.0000000000010079.

    PMID: 29538200
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    The significance of early screening with echocardiography in eosinophilic granulomatosis with polyangiitis.

    Tsugu T, Nagatomo Y, Yamada Y, et al.

    Journal of medical ultrasonics (2001) 2016; (43(4)):527-31 doi:10.1007/s10396-016-0728-7.

    PMID: 27372664
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    Loeffler endocarditis with intracardiac thrombus: case report and literature review.

    Zhang Q, Si D, Zhang Z, Zhang W

    BMC cardiovascular disorders 2021; (21(1)):615 doi:10.1186/s12872-021-02443-2.

    PMID: 34961478
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    A case report of Löffler endocarditis in idiopathic hypereosinophilic syndrome: recovery is possible.

    Abayazeed RM, Abdel-Hay MA, Elfwal S, Hssanein M

    European heart journal. Case reports 2018; (2(2)):yty030 doi:10.1093/ehjcr/yty030.

    PMID: 31020113
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    [Pediatric idiopathic hypereosinophilic syndrome with pulmonary embolism: a case report and review of literature].

    Dong N, Dong XY

    Zhonghua er ke za zhi = Chinese journal of pediatrics 2017; (55(10)):775-779 doi:10.3760/cma.j.issn.0578-1310.2017.10.013.

    PMID: 29050117
  12. 12

    Acute pulmonary embolism and deep vein thrombosis secondary to idiopathic hypereosinophilic syndrome.

    Li D, Xu L, Lin D, et al.

    Respiratory medicine case reports 2018; (25()):213-215 doi:10.1016/j.rmcr.2018.09.006.

    PMID: 30237972
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    Hyepereosiniphilic syndrome and COVID-19: 2 case reports.

    Sherafati A, Rahmanian M, Sattarzadeh Badkoubeh R, et al.

    Journal of cardiothoracic surgery 2023; (18(1)):158 doi:10.1186/s13019-023-02241-1.

    PMID: 37085890
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    Multiple Cerebral Infarcts and Encephalopathy as the First Clinical Manifestations of Hypereosinophilic Syndrome: A Case Report and Narrative Review.

    Romano S, Avola G, Angeli MC, et al.

    Pulse (Basel, Switzerland) 2024; (12(1)):106-112 doi:10.1159/000539379.

    PMID: 39473614
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    Hypereosinophilic syndrome presenting as acute ischemic stroke, myocardial infarction, and arterial involvement: A case report.

    Sun RR, Chen TZ, Meng M

    World journal of clinical cases 2022; (10(11)):3547-3552 doi:10.12998/wjcc.v10.i11.3547.

    PMID: 35582049
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    Myocarditis with neurological and dermatological involvement in idiopathic Hypereosinophilic syndrome: Case report.

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    Hypereosinophilic syndrome with multiorgan involvement: an interdisciplinary work-up.

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    BMJ case reports 2021; (14(2)) doi:10.1136/bcr-2020-240243.

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    Hypereosinophilic dermatitis: generalised lichenification and gyrate erythema as the sole manifestation of idiopathic hypereosinophilic syndrome.

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    Idiopathic hypereosinophilic syndrome with pulmonary hypertension.

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    Clinical analysis of hypereosinophilic syndrome first presenting with asthma-like symptoms.

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    Single-Organ and Multisystem Hypereosinophilic Syndrome Patients with Gastrointestinal Manifestations Share Common Characteristics.

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    Rare manifestation of hypereosinophilic syndrome: Diffuse-type hair loss with massive perifollicular eosinophils.

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This page explains the symptoms and organ involvement of Hypereosinophilic Syndrome (HES) for educational purposes only. It does not replace professional medical advice. Always consult your healthcare provider or seek emergency care if you experience new or severe symptoms.

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