Iron Side Effects and Warnings

Safety Issues

Iron supplements commonly cause gastrointestinal upset, but, when taken at recommended dosages, serious adverse consequences are unlikely. However, excessive dosages of iron can be toxic—damaging the intestines and liver, and possibly resulting in death. Iron poisoning in children is a surprisingly common problem, so make sure to keep your iron supplements out of their reach.

Mildly excessive levels of iron may be unhealthy for another reason: it acts as an oxidant (the opposite of an antioxidant), perhaps increasing the risk of cancer and heart disease (although this is controversial). ¹ Elevated levels of iron may also play a role in brain injury caused by stroke . ² In addition, excess iron appears to increase complications of pregnancy , ³ and, if breastfed infants who are not iron-deficient are given iron supplements, the effects may be negative rather than positive. ⁴

Note: Simultaneous use of iron supplements and high-dose vitamin C can greatly increase iron absorption, possibly leading to excessive iron levels in the body. ^{5 6 7 8 9 10 11} One study found that iron does notimpair absorption of the drug methotrexate . ¹²

Interactions You Should Know About

If you are taking:

• Antibiotics in the tetracycline or quinolone ( Floxin , Cipro ) families; levodopa ; methyldopa ; carbidopa ; penicillamine ; thyroid hormone ; calcium ; soy ; zinc ; copper ; or manganese : To avoid absorption problems, wait at least 2 hours following your dose of medication or supplement before taking iron.

• Drugs that reduce stomach acid such as antacids , H 2 blockers , and proton pump inhibitors : You may need extra iron.

• High doses of vitamin C : You may absorb too much iron.

• ACE inhibitors : Iron may reduce coughing side effect; however, to avoid absorption problems, you should wait at least 2 hours following your dose of medication before taking iron.