Iron supplement

Iron supplements, also known as iron salts and iron pills, are a number of iron formulations used to treat and prevent iron deficiency including iron-deficiency anemia.^[11][12] For prevention they are only recommended in those with poor absorption, heavy menstrual periods, pregnancy, hemodialysis, or a diet low in iron.^[12][13] Prevention may also be used in low birth weight babies.^[12] They are taken by mouth, injection into a vein, or injection into a muscle.^[12] While benefits may be seen in days, up to two months may be required until iron levels return to normal.^[14]

Common side effects include constipation, abdominal pain, dark stools, and diarrhea.^[14] Other side effects, which may occur with excessive use, include iron overload and iron toxicity.^[11][13] Ferrous salts used as supplements by mouth include ferrous fumarate, ferrous gluconate, ferrous succinate, and ferrous sulfate.^[13] Injectable forms include iron dextran and iron sucrose.^[13] They work by providing the iron needed for making red blood cells.^[14]

Iron pills have been used medically since at least 1681, with an easy-to-use formulation being created in 1832 using chicken liver extracts and the majority from plants.^[15] Ferrous salt is on the World Health Organization's List of Essential Medicines.^[16] Ferrous salts are available as a generic medication and over the counter.^[11] Slow-release formulations, while available, are not recommended.^[12] In 2021, ferrous sulfate was the 105th most commonly prescribed medication in the United States, with more than 6 million prescriptions.^[17][18]