People with ET are at high risk of blood clots (thrombosis) and bleeding (haemorrhagic) events. Medication can reduce the platelet count, make the platelets less ‘sticky’, and decrease the likelihood of bleeding and clotting complications. Clotting episodes are more common and 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)

The risk factors for these clotting events include being over sixty years of age, and whether or not you have had a clot in the past. There are also a variety of risk factors for heart attacks and strokes that are important too; they include:

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

Bleeding complications in ET are less common than clots and are less likely if the platelet count is less than 1000 million per ml. Bleeding can appear in a variety of forms, from easy bruising and nosebleeds, to bleeding from the digestive system and sometimes in the brain. Less common complications include a risk of developing acute myeloid leukaemia or myelofibrosis. Some of the drugs we use to treat ET can increase the risk of developing acute leukaemia.

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