The iron supplement ferrous sulfate is an iron salt with the chemical formula FeSO₄.A greenish or yellow-brown or white crystalline solid or powder, Ferrous sulfate is also called iron sulfate, green vitriol, and iron vitriol.

Ferrous Sulfate is an essential body mineral. Ferrous sulfate is used to treat iron deficiency anemia (a lack of red blood cells caused by having too little iron in the body). Iron salts are one type of the mineral iron. People often use them as a supplement to treat iron deficiency.

The body primarily uses iron as part of the red blood cell proteins myoglobin and haemoglobin, which are essential for transporting and storing oxygen.

Iron also plays an important role in the formation of hormones, the health and development of the nervous system, and basic cell functioning.