Blood viscosity, also known as blood viscosity, is severely below normal at 0.43 mPa-s and is usually found in patients with severe anemia as well as coagulation factor deficiencies. Normal blood viscosity ranges from 3.84 to 5.30 mPa-s in men and 3.39 to 4.41 mPa-s in women. A blood viscosity of 0.43 mPa-s means that the patient’s blood viscosity is much lower than normal, indicating that the patient may have a severe anemia or a clotting factor deficiency. If the patient’s blood viscosity is low due to anemia, he/she can be given multivitamin iron oral solution, folic acid tablets, vitamin B12 and other supplements according to the deficient elements, and he/she can also eat more iron-rich foods and vitamin C-rich foods. If there is a lack of coagulation factors, coagulation factors need to be supplemented. It can be supplemented by plasma, cold precipitation and other methods. Patients should go to the hospital for examination and treatment in time when the blood viscosity of 0.43 mPa-s occurs, so as to avoid fainting due to severe anemia.