Oral iron: iron deficiency anaemias (Formulary)

Iron deficiency should be regarded as a symptom. Investigation of the underlying cause is vital.  Haemoglobin should rise by approximately 20 grams/litre (2 grams/100mL) over 3 to 4 weeks.  Once it has reached reference range, continue treatment for a further 3 months in order to replenish iron stores, and then stop.  Failure to respond as predicted suggests other underlying factors may be contributing to the anaemia. 

Gastric irritation is the most common side-effect of iron therapy and is related to the content of elemental iron.  A gradual increase in dose can help prevent some gastric side-effects.  Modified-release preparations are not recommended as they deliver most of their iron to the small intestine where it is poorly absorbed. 

A range of oral iron preparations is available over the counter. 

Iron absorption is increased when taken on an empty stomach and 1 tablet of ferrous sulfate/fumarate once daily is usually adequate for prophylaxis.  Where more frequent dosing is given it is important to allow at least 8 hours between doses.