Polycythemia vera is a slow-growing blood cancer in which your bone marrow makes too many red blood cells. These excess cells thicken your blood, slowing its flow. They also cause complications, such as blood clots, which can lead to a heart attack or stroke.
Visit the doctor, if you notice these symptoms---
Headache
Dizziness
Bleeding or bruising, usually minor
Weakness
Fatigue
Blurred vision
Excessive sweating
Painful swelling of one joint, often the big toe
Shortness of breath
Numbness, tingling, burning or weakness in your hands, feet, arms or legs
A feeling of fullness or bloating in your left upper abdomen due to an enlarged spleen
Fevers
Unexplained weight loss.