Enlarged red blood cells should not cause any health symptoms or problems. The reason that the red blood cells grow large is normally because of a deficiency in folic acid or vitamin B12. The body responds by producing the large red blood cells. Most people will have a diet that is mixed enough to prevent this from occurring, so the more likely reason for the enlarged red blood cells is the body's inability to absorb vitamin B12. This is called pernicious anemia. Pernicious anemia is when the stomach cells no longer produce a protein called intrinsic factor and the vitamins cannot be absorbed properly. There is treatment available for pernicious anemia and this involves an injection of vitamin B12. The treatment is injected because taking a tablet or supplement of vitamin B12 by mouth would not be possible because of the absorption issues. Once the injections have corrected the deficiency a dose of vitamin B12 is required every three months for the rest of the life of the patient, and most people will make a full recovery. The most common cause of enlarged red blood cells in the western world is excessive intake of alcohol. If a person drinks more than two (for women) or three (for men) units of alcohol a day then this is most likely the reason for enlarged red blood cells. A doctor will normally perform a liver function test, and this can sometimes show as normal. This doesn't mean that the red blood cells are a normal size and reducing alcohol intake can quickly assist in reducing the red blood cells back to their normal size. The improvement will normally be evident within three months. Other problems that can cause red blood cells to be enlarged are abnormal bone marrow production and thyroid problems.
Large red blood cells...or Macrocytosis does not CAUSE health problems, Macrocytosis is the RESULT of a health problem. Usually Vitamin B-12 deficiency, Folate deficiency, liver disease, alcoholism, a side effect of drug therapy for cancers... Such as chemo therapy, It can also be caused from the body replenishing the red blood cells lost as a result from blood loss from trauma or donating blood, and the body trying to correct Anemia.