Being a component of many proteins and enzymes, iron is an essential microelement for humans. However, this element can also be toxic when present in excess because of its ability to generate reactive oxygen species. This dual nature imposes a strict regulation mechanism of the iron concentration in the body. In humans, systemic iron homeostasis is mainly regulated on the level of intestinal absorption. A patient diagnosed with excess iron in the body should be treated safely and effectively. And the therapy should be consistent with the treatment of concurrent diseases. On the other hand, iron deficiency is one of the most common disorders affecting humans. Iron-deficiency anaemia continues to represent a major public health problem worldwide, being prevalent among pregnant women, where it represents an important risk factor for maternal and infant health. A problem detecetd relatively recently and therefore not fully clarified yet is the iron therapy in patients with restless legs syndrome (RLS). RLS is a common neurological condition defined clinically as the urge to move the legs. Reduced brain iron is strongly associated with restless legs syndrome. RLS can also be a consequence of iron deficiency in the body. This review will focus on iron as an element whose abnormal metabolism or deficiency in the body can lead to diseases e.g. anaemia, restless legs syndrome and iron overload. Here we will describe methods of therapy, paying particular attention to the types and dosages of medications.