Formula Fe
Molar Mass (g·mol−1) 55.84
Physical State solid
Density (g·cm−3) 7.87
Melting Point (°C) 1538
Boiling Point (°C) 2,861
CAS Number 7439-89-6
PUB Number 23925
Drugbank ID DB01592
Solubility insoluble in water


Iron is an important mineral that is vital for the human body. It plays a crucial role in the formation of hemoglobin, the red pigment in the blood that is responsible for oxygen transport in the body. An iron deficiency can therefore lead to anemia, fatigue and reduced performance.

In medicine, iron is often used as a dietary supplement to treat or prevent iron deficiency conditions. Iron is also taken for certain diseases where iron requirements are increased, such as anemia. It is important that iron be taken under a doctor's supervision to ensure proper dosage and to avoid possible side effects.

Foods such as meat, fish, legumes and whole grains are good sources of iron.



Iron is necessary for maintaining optimal health, especially for the formation of red blood cells, which carry oxygen throughout the body. An iron deficiency means that the body cannot produce enough healthy red blood cells. Iron deficiency anemia occurs when the body's iron stores fall to too low a level and the stored iron is insufficient to support normal red blood cell production. Insufficient iron in the diet, impaired iron absorption, bleeding, pregnancy, or iron loss through the urine can lead to iron deficiency. Symptoms of iron deficiency anemia include fatigue, shortness of breath, palpitations, dizziness and headaches. Taking iron in the form of dietary supplements, such as ferrous sulfate, allows iron levels to rise more rapidly when dietary intake and iron stores are inadequate.


Orally administered iron has widely varying bioavailability depending on circumstances, including the valence of the iron (Fe2+ or Fe3+), dietary intake, and degree of iron deficiency. Bivalent iron is more soluble and therefore usually has a higher bioavailability than trivalent iron (Fe3+). Absorption occurs mainly in the small intestine, particularly in the duodenum and proximal jejunum. Approximately 60% of the iron is absorbed into the erythrocytes. The rest of the iron is found in muscle tissue (as part of myoglobin) and in a variety of different enzymes, as well as in its storage form, ferritin.


Side effects

  • darkening of the stools
  • abdominal pain
  • heartburn
  • nausea
  • constipation
  • Flatulence
  • Vomiting
  • Diarrhea

Contraindications and precautions

Iron-containing products carry a risk of overdose, especially in children. Iron in excessive amounts is toxic to the gastrointestinal system, cardiovascular system, and central nervous system. Possible symptoms following excessive iron intake include nausea, bloating, abdominal pain, diarrhea, constipation, and black/tear stools. Symptoms of overdose in the more advanced stages include bluish lips, fingernails and palms, drowsiness, tachycardia, seizures, metabolic acidosis, liver damage and cardiovascular dysfunction. If these symptoms occur, a physician must be contacted immediately.

Markus Falkenstätter

Markus Falkenstätter

Markus Falkenstätter ist Autor zu pharmazeutischen Themen in der Medizin-Redaktion von Medikamio. Er befindet sich im letzten Semester seines Pharmaziestudiums an der Universität Wien und liebt das wissenschaftliche Arbeiten im Bereich der Naturwissenschaften.

Mag. pharm Stefanie Lehenauer

Mag. pharm Stefanie Lehenauer

Stefanie Lehenauer ist seit 2020 freie Autorin bei Medikamio und studierte Pharmazie an der Universität Wien. Sie arbeitet als Apothekerin in Wien und ihre Leidenschaft sind pflanzliche Arzneimittel und deren Wirkung.

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