People with PV are at a high risk of blood clots (thrombosis) and bleeding (haemorrhagic) events. The chance of both bleeding and clotting complications of PV can be reduced with medication to reduce blood stickiness and also lower the red blood cell and platelet counts.

Clotting episodes are more common than bleeding episodes and they have a significant impact on survival. Examples of the different types of blood clots include

• Deep vein thrombosis (DVT)
• Pulmonary embolism (lung clot)
• Myocardial infarction (heart attack)
• Cerebrovascular accident (stroke)
• Minor thrombotic events (minor clots)
• Transient ischaemic attack (TIA - minor stroke)
• Superficial thrombophlebitis (varicose veins)
• Erythromelalgia (painful and swollen finger/toe)

People with PV who are over age 60 or have had a clot in the past are at higher risk for these events. There are other risk factors for heart attacks and strokes that are important too:

• High blood pressure
• Cigarette smoking
• Diabetes
• High cholesterol

Bleeding complications: Bleeding can appear in a variety of forms, from easy bruising and nosebleeds, to bleeding from the gut and sometimes in the head.

Long-term less common complications include a risk of developing acute myeloid leukaemia or myelofibrosis. The risk of developing myelofibrosis is about 15% for patients with PV.

You can learn about preventing complications, taking care of yourself and feeling well on our Support and Top Tips pages.