Can I have diarrhea if I take iron supplements?

Fact Checked

Iron supplements can generate gastrointestinal side effects including diarrhea. If an individual develops diarrhea, abdominal discomfort or other digestive issues and currently using iron supplements, a doctor should be consulted to ensure that the individual is using the proper amount of iron to meet with the nutritional needs. If the diarrhea is blood streaked, it indicates that the individual has taken too much iron and requires immediate medical care.

What are the side effects?

It is important to note that iron transports oxygen in the red blood cells and takes part in the production of energy in the body. If the individual is at risk for iron deficiency due to pregnancy, iron deficiency anemia, lack of iron in the diet, bleeding condition or another health issue, the doctor might recommend iron supplements to help the individual meet with his/her daily requirements.

The typical side effects of iron supplements involve the gastrointestinal system. The usual side effects include the following:

  • Heartburn
  • Nausea
  • Diarrhea
  • Constipation
  • Abdominal pain

The iron supplements taken orally can also cause black stools that can be mistaken as an indication of gastrointestinal bleeding. Black stools that occur once the body breaks down the iron in the supplements are a harmless side effect.


Due to the health risk of using excessive amounts of iron, it is recommended not to take more that the dietary allowance for iron without medical supervision.

Iron supplements
Early symptoms of iron toxicity include fatigue, weakness, joint pain and abdominal pain.
  • Women between 19-50 years old require 18 mg per day of iron.
  • Pregnant women require 27 mg iron per day.
  • Breastfeeding women over 19 years old require 9 mg iron per day.

Take note that these groups face the risk for iron loss due to menstruation and childbearing. As for men ages 19 and older as well as women over 50 require 8 mg of iron every day. If an individual was diagnosed with iron deficiency anemia or another health condition that requires iron, he/she might need more than the recommended daily need.

Iron overload

When the individual exceeds the nutritional requirements for iron, the body stores excess amounts in the bone marrow, muscles, spleen and liver. Using iron supplements for an extended period can lead to iron toxicity.

Early symptoms of iron toxicity include fatigue, weakness, joint pain and abdominal pain. In the late stages, iron overload can lead to serious health issues such as diabetes, damage to the heart and liver and arthritis. The best way to avoid taking too much supplement is to strictly observe the instructions given by the doctor to be consumed on a daily basis.

Precautions to bear in mind

The tolerable level of intake for iron or the amount that can be taken safely is 45 mg each day. Consuming more than this amount can cause the destruction of the gastrointestinal cells, resulting to vomiting and blood-streaked diarrhea.

Overdose on iron supplements can be deadly. Eating food with iron supplements can help prevent nausea, diarrhea or other digestive issues. On the other hand, taking iron supplements with milk products, coffee, cereal or tea can minimize the amount of iron the body absorbs. If the individual does not experience any digestive side effects, he/she can take the supplements on an empty stomach to ensure proper absorption.

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