From the Guidelines
Low iron saturation and constipation can be effectively managed by taking an iron supplement, such as ferrous sulfate, once daily, and implementing strategies to mitigate constipation, including increased water and fiber intake, and considering a stool softener like docusate sodium. According to a recent clinical practice update on the management of iron deficiency anemia, oral iron supplements are a reasonable choice for treating low iron saturation, with ferrous iron salts being a cost-effective option 1. However, it's essential to be aware that oral iron supplements can cause constipation in approximately 12% of patients, as well as other side effects like diarrhea and nausea 1. To minimize the risk of constipation, it's recommended to take iron supplements once daily, as taking them more frequently does not improve absorption but may increase side effects 1. Additionally, certain dietary manipulations, such as taking iron with 80 mg of ascorbic acid on an empty stomach, may improve iron absorption, although more research is needed to confirm the effectiveness of this approach 1.
Some key considerations for managing constipation while taking iron supplements include:
- Increasing daily water intake to at least 8-10 glasses
- Consuming more fiber-rich foods like fruits, vegetables, and whole grains (aiming for 25-30g of fiber daily)
- Considering a stool softener like docusate sodium (100 mg once or twice daily) alongside the iron supplement
- Engaging in regular physical activity to stimulate bowel movements
- Avoiding powerful inhibitors of iron absorption, such as tea and coffee, for at least an hour after taking iron 1. If constipation persists, a gentle laxative like Miralax (polyethylene glycol 17g daily) may be necessary. It's crucial to consult a healthcare provider if symptoms do not improve within 2-3 weeks.
From the FDA Drug Label
May cause gastrointestinal discomfort, nausea, constipation or diarrhea. May cause gastrointestinal discomfort, nausea, constipation or diarrhea. Both ferrous sulfate (PO) 2 and ferrous gluconate (PO) 3 can cause constipation as a side effect.
- Key points:
- Iron supplements can cause gastrointestinal side effects, including constipation.
- Patients with low iron saturation taking these supplements may experience constipation. It is recommended to consult a healthcare professional for advice on managing constipation while taking iron supplements.
From the Research
Iron Saturation and Constipation Issues
- Iron deficiency anemia and pre-anemic iron deficiency are common pathologies that require oral iron supplementation as the first line of treatment 4
- Oral iron supplementation can cause gastrointestinal side effects, including constipation, which can reduce compliance 4, 5
- Ferrous sulfate is a commonly prescribed oral iron supplement, but it can cause significant gastrointestinal side effects, including constipation, in adults 5
- Other oral iron supplements, such as ferrous bisglycinate, may be better tolerated and cause fewer gastrointestinal side effects, including constipation 6, 7
Comparison of Oral Iron Supplements
- Ferrous bisglycinate has been shown to be as effective as ferrous sulfate in preventing iron deficiency and anemia during pregnancy, with fewer gastrointestinal complaints 6
- A systematic review and meta-analysis found that ferrous bisglycinate supplementation resulted in higher hemoglobin concentrations and fewer reported gastrointestinal adverse events, including constipation, compared to other iron supplements in pregnant women 7
- Another study found that ferrous sulfate, ferrous fumarate, ferrous ascorbate, and carbonyl iron were equally effective in treating iron-deficiency anemia in pregnant women, but ferrous fumarate caused more adverse effects, including constipation 8
Gastrointestinal Side Effects of Oral Iron Supplements
- Ferrous sulfate supplementation has been shown to significantly increase the risk of gastrointestinal side effects, including constipation, compared to placebo or intravenous iron 5
- The risk of gastrointestinal side effects, including constipation, may be lower with other oral iron supplements, such as ferrous bisglycinate 6, 7