Folic acid tablet available in 400 mcg and 5 mg. folic acid is used to treat folic acid deficiency and certain types of anemia (lack of red blood cells) caused by folic acid deficiency. Folic acid is sometimes used with other medications to treat pernicious anemia. Folic acid used alone will not treat pernicious anemia and other anemias not related to Vitamin B12 deficiency.