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Living with Familial erythrocytosis

An inherited condition with too many red blood cells, which can cause headaches and blood clots in some people.

Understanding Familial erythrocytosis

Familial erythrocytosis is an inherited condition with too many red blood cells (erythrocytes), the cells that carry oxygen.

Symptoms can include headaches, dizziness, nosebleeds, and shortness of breath. The extra red blood cells raise the risk of abnormal blood clots, which can block blood flow to organs like the heart, lungs, or brain. Many people have only mild symptoms or never have problems.

Signs & symptoms

GARD describes these symptoms in its summary:

  • Headaches
  • Dizziness
  • Nosebleeds
  • Shortness of breath
  • Blood clots in arteries and veins

Not everyone has every symptom. GARD's list comes from the Human Phenotype Ontology.

Diagnosis

  1. Talk with your doctor

    Share the symptoms you've noticed, when they started and your family health history. Notes and photos can help.

  2. See a specialist

    Your doctor may refer you to a specialist who knows rare conditions.

  3. Ask which tests can help

    Your care team will decide which exams and tests can confirm the diagnosis.

Care & treatment

Care team
A doctor familiar with rare conditions, plus specialists as needed
Expert care
Ask about multidisciplinary care centers for rare conditions
Treatment
GARD doesn't list specific treatments for this condition. Your care team will tailor care to your symptoms.
Research
Clinical trials and observational studies may be options. See the research section below.

General information, not medical advice. Your care team makes the decisions.

Everyday life

Living with a rare condition is easier with support.

  • Connect with rare disease patient organizations for support
  • Keep notes on symptoms, changes and questions for appointments
  • Ask about patient registries that help research
  • Look into financial aid and travel resources for care visits
Bring these questions to your next doctor visit
Which tests find the cause of my high red blood cell count?
How can I lower my risk of blood clots?
Which specialist, such as a blood doctor, should follow me?

Quick facts

GARD doesn't describe a cause for this condition yet.

Also known as: erythrocytosis, familial; familial polycythemia; hereditary polycythemia (disease); hereditary pure erythrocytosis

Patient organizations

Rare-disease groups that can help

Source: NIH GARD · Familial erythrocytosisGARD ID 22884 · GARD page updated September 2026 · Plain-language summary by Know Rare; editorial review pending. General information, not medical advice.

You are more than your diagnosis

Perspectives from people navigating life with Familial erythrocytosis.

Explore the Familial erythrocytosis blog

Explore research for Familial erythrocytosis

Explore actively recruiting Familial erythrocytosis studies with HealthSpark.

HealthSpark

Find actively recruiting studies for Familial erythrocytosis with HealthSpark. Share your city to explore research near you.

  • Recruiting studies from ClinicalTrials.gov
  • Share your city to look for research near you
  • Eligibility is confirmed by the study team

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Powered by HealthSpark, our AI chat helper · Study information from ClinicalTrials.gov · Eligibility is confirmed by the study team.

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