Ferrous gluconate is available over the counter, but does ferrous sulfate lead to constipation? According to discussions on Reddit, many users have noted that ferrous sulfate can indeed cause constipation. In contrast, ferrous lactate may be a better option for some individuals. When comparing the absorption rates of ferrous gluconate and ferrous sulfate, it’s essential to consider the role of supplements like cal mag citrate 1:1, which can help alleviate some gastrointestinal issues. Ultimately, if you’re choosing between ferrous gluconate and ferrous sulfate, it’s wise to consider how each might affect your digestive health, especially if you’re also taking cal mag citrate 1:1.