Iron supplements are not to be given to normal birth weight infants below 2 years of age, particularly so because breast milk contains adequate iron for infants. Even in older children, iron supplements can not be given with calcium-containing items (such as milk) because the absorption is delayed leading to abdominal symptoms (e.g. pain, colic etc.) and constipation. Even fruits (such as apple) with iron cause constipation in children. Excessive iron in children also can lead to growth retardation and increased risk of infection (since iron is also used by germs to grow).
Only in low birth-weight infants special iron products (containing sodium feredetate) are sometimes given provided there is proven iron deficiency.
Even in adults, iron supplements are to be given only when there is proven deficiency. Except in bleeding disorders, there is hardly any loss of iron which is recycled by the body.