In most patients, blood viscosity is asymptomatic and is usually detected during a physical examination or blood biochemistry test. Prolonged thickening of blood can lead to insufficient nutrient and oxygen supply to the organs, which may result in dizziness, headache, memory loss, etc. A few patients also have coagulation disorders. 1. Insufficient blood and oxygen supply to organs: dizziness, headache, tinnitus, lack of concentration, memory loss, chest tightness, numbness of limbs, loss of vision. 2. Coagulation disorders: nosebleeds, bleeding gums, bleeding ecchymosis of the skin and mucous membranes. Regardless of the age group, blood viscosity can occur. When the above symptoms appear after a physical examination or abnormal blood biochemical tests, it is important to identify the cause and take appropriate interventions to avoid leading to permanent damage.