Anemia is classified as mild, moderate, severe or very severe depending on the severity. When hemoglobin is >90g/L and below the normal value, it is called mild anemia, the normal value is 130g/L for men and 120g/L for women. 60-89g/L is moderate anemia, 30-59g/L is severe anemia, and less than 30g/L is very severe anemia. Above moderate anemia, you need to go to a hospital for specialist treatment and actively search for the cause of anemia in order to recover, otherwise it will cause damage to multiple organs. Common symptoms of anemia include pale skin and mucous membranes, dizziness, headache, tinnitus, tiredness, lack of concentration, muscle weakness, easy fatigue, low immunity, easy infection, and in severe cases, fainting, disturbance of menstrual cycle in women, and affecting blood supply to the heart to form anemic heart disease.