Ferrous glycine sulfate, elemental iron, iron (III) phosphate, and iron lactate are all forms of iron supplements that play a crucial role in addressing iron deficiency. Among these, ferrous fumarate is notable, with a concentration of 60 mg/ml, often found in iron pills. It is important to consider various factors, including whether calcium citrate causes kidney stones. Research indicates that excessive calcium intake, especially in the form of calcium citrate, may increase the risk of kidney stones in susceptible individuals. Therefore, when taking iron supplements, one should be mindful of their calcium intake, particularly if they are consuming calcium citrate, as it is essential to maintain a balanced diet to minimize potential health risks. In summary, while ferrous fumarate and other iron supplements are beneficial, it is crucial to be aware of the implications of calcium citrate and its potential to cause kidney stones.