Iron deficiency and iron deficiency anaemia, including in pregnancy, after heavy periods, and in children and adolescents whose intake or absorption is low.

Iron is the core of haemoglobin, the molecule red blood cells use to carry oxygen. In this preparation the iron sits inside a polymaltose shell, so it is released and taken up steadily rather than flooding the gut. The absorbed iron restocks the bone marrow and haemoglobin rises over the following weeks.

Dark or black stools, which are harmless and expected, along with constipation, nausea, stomach discomfort and a metallic taste. Liquid forms can stain the teeth, so use a straw and rinse.

Do not take iron unless deficiency has been confirmed, because too much iron is harmful. Keep it well out of reach of children: an overdose of iron tablets is a serious emergency in a small child. Separate it by at least two hours from tea, coffee, milk, antacids and thyroid or tetracycline medicines, which all reduce absorption. Treatment usually continues for months after the blood count recovers, to refill the body's stores.