Ferrous bisglycinate chelate contains 28 mg of iron, while Firstiv iron features ferrous gluconate at 324 mg. Additionally, there is a significant amount of ferrous fumarate at 18 mg, available in liquid form. It’s important to note that when taking these iron supplements, some individuals may experience citracal constipation, a common side effect. To mitigate this issue, it is advisable to monitor your intake and consider dietary adjustments. Overall, while ferrous bisglycinate and other iron supplements are beneficial for boosting iron levels, managing citracal constipation is essential for maintaining digestive health.