Polycythemia Vera: Finding the Right Balance

Polycythemia Vera and Blood Clots: Warning Signs and How To Lower Your Risk

Medically reviewed by Warren Brenner, M.D.

Written by Carrie Madormo, RN, MPH

Posted on September 8, 2026

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Key Takeaways

Polycythemia vera (PV) is a rare blood cancer that causes the body to make too many red blood cells, which thickens the blood and raises the risk of dangerous blood clots.

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Polycythemia vera (PV) is a rare form of blood cancer that can raise your risk of blood clots. Blood clots form when blood cells and proteins clump together. If blood clots block blood flow, it’s a medical emergency that needs to be treated immediately.

People with PV have bone marrow that produces too many red blood cells, making their blood thick and slow. This can lead to complications like heart attack, stroke, and blood clots. Fortunately, there are treatment options available to manage PV and lower your risk of blood clots.

In this article, we’ll cover how to recognize warning signs of a blood clot and what to do to lower your risk.

🗳️ Have you experienced blood clots or complications since living with polycythemia vera (PV)?

Deep vein thrombosis (DVT)

Pulmonary embolism (PE)

Heart attack or stroke

More than one of these

Blood Clots With PV

Blood clots develop when blood cells called platelets clump together. When you cut yourself, your blood naturally clots to prevent too much blood loss. However, when blood clots block the blood vessels, it’s dangerous.

PV raises the risk for blood clots because the blood is thick and can’t move easily along the blood vessels. When blood sits in place, there’s an increased risk of clotting.

For some people, a blood clot may be the first sign of PV.

Risk Factors for Blood Clots

A 2023 analysis found that out of 20,089 people with PV, 25.1 percent developed a blood clot over the 4.3 years of the study. Blood clots occurred in 13.3 percent of people with low-risk PV and 50.2 percent of those considered high risk because of a previous blood clot.

Anyone with PV is at risk of blood clots, but certain factors can raise the risk even more. Your risk is higher if you’re over 60 and have a history of previous blood clots.

Types of Blood Clots

There are different types of blood clots, depending on where they form in the body. A blood clot in the lungs is called a pulmonary embolism (PE).

This type of clot usually starts somewhere else in the body, then travels through the veins to the lungs. A PE is a medical emergency and needs immediate treatment.

When a blood clot forms in an arm or leg, it’s called a deep vein thrombosis (DVT). These clots are more common in the legs than the arms.

DVTs form in veins deep in the body. If a clot in the leg or arm breaks free and travels to the lungs, it can cause a PE.

In the 2023 review, DVTs were the most common clot, followed by PEs, and then superficial thrombophlebitis — blood clots in the veins just below the skin.

When Are Blood Clots Life-Threatening?

Blood clots can become life-threatening when they block blood flow to the heart, lungs, or brain. A blood clot in the brain can cause a stroke, and a blood clot in the heart can cause a myocardial infarction (heart attack).

In the 2023 review of 20,089 people with PV, 7.1 percent experienced a stroke, and 6.4 percent had a myocardial infarction.

Knowing the signs of a PE can help you know when to seek treatment. It’s estimated that up to 1 in 3 people with a PE die within hours of developing symptoms. Quick action is essential.

Warning Signs and Symptoms of Blood Clots
It’s critical to go to the emergency room if you notice any potential symptom of a clot.
Deep Vein Thrombosis (usually occurs in a leg or arm)	Pulmonary Embolism
Pain	Sudden, sharp chest pain
Swelling	Lightheadedness
Warmth	Faintness
Redness or skin discoloration	Shortness of breath
Severe headache (if a clot forms in the veins in the brain)	Fast breathing
	Fast heartbeat
	Coughing and wheezing
	Cyanosis (blue, gray, or ashen skin or lips)

How To Lower Your Risk of a Blood Clot

PV is a chronic disease. This means there’s no cure. Fortunately, there are treatment options available to manage the disease and lower your risk of blood clots.

The goal of PV treatment is to lower the number of red blood cells in the blood and manage symptoms. Your treatment team will refer to your hematocrit level (the percentage of red blood cells in your blood) when starting or adjusting your treatment plan.

Smoking increases the risk of blood clots. When you’re exposed to tobacco smoke, your blood vessels narrow, making it harder for blood to flow.

In general, PV treatment will focus on keeping the hematocrit level below 45 percent for men and 42 percent for women, according to Blood Cancer United.

Follow Your PV Treatment Plan

Your PV care team will work with you to develop a treatment plan to lower your risk of blood clots. Your doctor will see you for regular appointments to monitor for any signs of clots or other complications.

Treatment options that help reduce the risk of blood clots include:

Low-dose aspirin — Taking low-dose aspirin every day can reduce blood thickness and lower your risk of clots, heart attack, and stroke.
Therapeutic phlebotomy — Regularly removing blood can reduce the number of red blood cells and lower your risk of blood clots. Many people with PV have their blood drawn regularly.
Interferons — Interferons are proteins that are injected into the blood to lower the number of red blood cells.
Janus kinase (JAK) inhibitors — Medications like ruxolitinib (Jakafi) can decrease the production of red blood cells, keeping your hematocrit level in a healthy range.
Hepcidin-mimetic therapy — Recently approved, rusfertide (Mimrylo) is a synthetic version of hepcidin (a hormone that regulates iron). In clinical trials, rusfertide controlled red blood cell levels while decreasing the need for phlebotomy.

Stay Physically Active

Moving your body keeps your blood moving. This can reduce the risk of blood cells clumping together and forming a clot. Sitting for long periods of time raises the risk of DVTs and PEs.

In one large study, blood clots occurred in 13.3 percent of people with low-risk PV and 50.2 percent of those considered high risk because of a previous blood clot.

Exercise is also a helpful way to maintain a healthy weight and manage stress. Aim to stay active throughout the day to lower the risk of DVTs.

Maintain a Healthy Weight

Maintaining a healthy weight helps lower your risk of heart disease and blood clots. Daily exercise and eating a nutrient-dense diet can help.

The Mediterranean diet offers anti-inflammatory benefits and may lower the risk of heart disease. This diet focuses on vegetables, fruits, whole grains, lean proteins, and healthy fats.

Avoid Smoking

Smoking increases the risk of blood clots in everyone, especially in people with PV. When you’re exposed to tobacco smoke, your blood vessels narrow, making it harder for blood to flow.

If you currently smoke, talk with your doctor about resources to help you quit. If you live with someone who smokes, talk with them about your health risks and make a plan to protect yourself.

Be Cautious in High Altitudes

People with PV are at risk of low oxygen levels in their blood. Spending time in high altitudes, especially when you’re not used to it, can also lower oxygen levels. While this may not cause a clot, it can lead to serious health problems.

Talk With Your Doctor

Talk with your PV specialist about your risk of blood clots and how to prevent them. Your healthcare team can explain your individual risk factors and develop the right treatment plan for you. Never hesitate to reach out to your team with questions.

If you suspect you have a blood clot, seek emergency medical care.