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How long does it take for Injectafer to work, when will I feel better?

Medically reviewed by Melisa Puckey, BPharm. Last updated on June 19, 2023.

Official answer


Injectafer infusions work rapidly and effectively to correct iron levels and some people start to feel an improvement in their symptoms within a week. It takes 2 to 3 weeks for the anaemia to be corrected and then you should have better concentration, more energy, and have less breathlessness and fatigue.

What is Injectafer used for?

Injectafer (ferric carboxymaltose injection) is FDA-approved to be used for

iron deficiency anemia (IDA) in

  • adult and pediatric patients 1 year of age and older who have either intolerance or unsatisfactory response to oral iron.
  • adult patients who have non-dialysis dependent chronic kidney disease.

iron deficiency in adult patients with heart failure and New York Heart Association class II/III, used to improve exercise capacity

What is Iron Deficiency Anemia?

Iron deficiency anemia is when you have a low number of red blood cells, due to not having low levels of iron.

  • iron is needed to make hemoglobin for red blood cells, which carry oxygen around the body.
  • when iron levels are low, the body makes less hemoglobin,and so less oxygen is carried around the body which leaves you feeling tired and short of breath.
  • once you have an injectafer infusion your iron levels are increased to an ideal level.
  • it then takes 2 to 3 weeks for the bone marrow to use the iron to make hemoglobin, for the red blood cells and the anemia should be corrected.

injectafer is an iron replacement infusion that can be given as a single dose or two separate doses that are separated by at least 7 days. Injectafer (ferric carboxymaltose injection) is an injectable iron replacement product. It comes as a single-dose vial containing either 100 mg / 2 mL, 750 mg iron /1 5 mL or 1,000 mg iron / 20 mL. Each mL of Injectafer contains 50 mg of elemental iron. It is manufactured by Daiichi Sankyo / American Regent.

Learn more: Injectafor dose (in more detail)

Bottom line:

  • iron deficiency anemia is caused by low iron levels
  • Injectafer corrects iron levels quickly.
  • the bone marrow takes 2 to 3 weeks to use the iron to make hemoglobin for red blood cells.
  • iron deficiency anemia symptoms start to improve within a week of having Injectafer and within 2 to 3 weeks of having correct iron levels anemia symptoms should have reduced significantly.


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