From the FDA Drug Label
Among the breastfed infants, adverse reactions included constipation and diarrhea but none of the adverse reactions reported were considered related to ferric carboxymaltose exposure through breastmilk The answer to the question of whether iron infusions cause constipation is yes, as constipation is listed as an adverse reaction in breastfed infants. However, it is noted that this is not considered related to ferric carboxymaltose exposure through breastmilk 1.
- Key points:
- Constipation is listed as an adverse reaction
- Not considered related to ferric carboxymaltose exposure through breastmilk
- No direct information on constipation as a side effect of iron infusions in the general population is provided in the label.
From the Research
Iron infusions can cause constipation as a side effect, though it's not as common as with oral iron supplements, with studies suggesting that about 2-5% of patients receiving intravenous iron experience constipation 2. The incidence of constipation may vary depending on the specific iron formulation used, such as iron sucrose, ferric carboxymaltose, or iron dextran. If constipation occurs after an iron infusion, increasing fluid intake, consuming more dietary fiber, and gentle physical activity can help alleviate symptoms. Over-the-counter stool softeners like docusate sodium or mild laxatives such as polyethylene glycol may be used if needed. Constipation from iron infusions typically resolves within a few days after treatment. The mechanism behind iron-induced constipation involves iron's direct effect on intestinal motility and its interaction with certain gut bacteria. Some studies have shown that ferric carboxymaltose is well tolerated in clinical trials, with most drug-related adverse events considered to be mild to moderate in severity, including constipation 3, 4, 5, 6. It is essential to note that while constipation is a potential side effect, the benefits of iron infusions in treating iron deficiency anemia often outweigh the risks, and healthcare providers should be consulted if constipation is severe or persists beyond a week after infusion 2. In general, improvements in haemoglobin levels were more rapid with ferric carboxymaltose than with ferrous sulfate, and ferric carboxymaltose was at least as effective as ferrous sulfate with regard to endpoints related to serum ferritin levels, transferrin saturation, and health-related quality-of-life 2, 3, 6. Overall, iron infusions, including ferric carboxymaltose, are effective and well-tolerated options for treating iron deficiency anemia, with constipation being a relatively rare side effect that can be managed with appropriate measures.