Ferrous sulfate tablets are an iron supplement commonly used in clinical practice in the past. Ferrous sulfate belongs to inorganic iron, and ferrous sulfate tablets are produced by several manufacturers in China, each of which produces significantly different specifications and packaging, but ferrous sulfate tablets are a relatively inexpensive drug that costs about ten dollars. Because ferrous sulfate tablets are inorganic iron, many people take them with a low absorption rate and with significant digestive side effects. Many people experience a range of discomforts such as nausea, bloating, loss of appetite and dark stools, and some patients are even forced to stop taking them because of digestive symptoms. Ferrous sulfate granules are now available, and ferrous sulfate granules can effectively reduce digestive side effects. Organic iron is also commonly used in clinical practice, including ferrous lactate and iron dextran. Organic iron has less side effects on the digestive tract and has a relatively high absorption rate.