Iron, a nutrient found in most animal products and some plant-based foods, makes up an important part of hemoglobin, an oxygen-carrying protein in red blood cells. Insufficient iron intake or absorption can cause iron deficiency anemia, leading to weakness, fatigue, irritability and difficulty concentrating. Iron supplements used to treat iron deficiency anemia may cause a variety of digestive side effects, including dark stools.
Stool Side Effects
Black stools are common while taking iron supplements, and typically indicate that the supplements are working properly, notes MedlinePlus Medical Encyclopedia. However, tarry or red-streaked stools may indicate an abnormal reaction to the iron supplements. Contact your doctor if you have these side effects.
Other Side Effects
Other common side effects of iron supplements include constipation, diarrhea, nausea and vomiting. Stool softeners such as docusate sodium can help with constipation associated with iron supplements, notes MedlinePlus Medical Encyclopedia. Contact your doctor if you experience severe cramps or stomach pain while taking iron supplements.
Minimizing Side Effects
Taking iron supplements with food may reduce the amount of iron absorbed, but it can also help to minimize side effects such as nausea and vomiting. If you must take iron with food, avoid taking it with foods that hinder iron absorption, such as calcium, dairy products, coffee, tea and high-fiber foods. Taking iron in smaller, divided doses may also help minimize side effects, recommends the National Institutes of Health Office of Dietary Supplements. Taking iron with food or in divided doses may not prevent dark stools, however.
Who Needs Iron Supplements
Most people should be able to get sufficient iron from food sources, notes MedlinePlus Medical Encyclopedia. However, people with increased iron needs or chronic malabsorption may need iron supplements to prevent a deficiency. Individuals at high risk for iron deficiency include teenage girls and women of childbearing age, pregnant women, preterm and low birth-weight infants, people with renal failure, people undergoing routine dialysis treatments and people with gastrointestinal disorders such as celiac disease and Crohn's disease, according to the National Institutes of Health Office of Dietary Supplements. Endurance athletes may also need additional iron.
