Oral iron supplements may cause constipation, resulting in fewer bowel movements or stools that are difficult to pass. A doctor can advise about supplementary iron and any gastrointestinal side effects.
Constipation affects around
Some medications and dietary supplements can worsen constipation. Individuals who take iron supplements for iron deficiency anemia or to obtain iron that they do not get in their diet may be
This article explores whether iron supplements cause constipation, examining the scientific evidence. It also offers tips for managing constipation and discusses when to contact a doctor.
According to a 2021 review, oral iron is the most common treatment for iron deficiency anemia due to its low cost, high bioavailability, and effectiveness.
However, the review authors noted that iron supplements may cause gastrointestinal side effects, such as constipation, abdominal pain, and bloating, in up to 60% of people who take them. The type of oral iron that doctors prescribe most is ferrous sulfate, but this has a high frequency of side effects compared with ferric iron sources.
The review further explains that iron supplements typically contain more iron than the body can absorb. Therefore, a large amount remains in the gut, affecting the balance of gut bacteria. In addition, older
This may result in stool hardening and constipation as water
A person may be able to
- eating more fiber by including foods such as vegetables, whole grains, legumes, fruits, and nuts in the diet
- drinking plenty of water
- avoiding processed foods, fast food, and foods with little or no fiber, such as meat
- staying physically active
- trying bowel training by aiming to have a bowel movement at the same time each day — for example,
15-45 minutesafter eating breakfast
- asking a doctor which supplements or medications worsen constipation and if it may be safe to stop taking them
- asking a healthcare professional about whether taking laxatives may be suitable
People with constipation that does not resolve should speak with a doctor. A healthcare professional may recommend over-the-counter medications
- stool softeners
- osmotic agents — for example, milk of magnesia
- fiber supplements
- lubricants such as mineral oil
- stimulant laxatives
In addition, a doctor may prescribe the following medications:
Depending on an individual’s health history, doctors may also recommend biofeedback therapy or surgery.
People should also consult a doctor to determine if they have any underlying medical conditions related to constipation or iron deficiency. Additionally, if someone with constipation has any of the
- blood in the stool
- rectal bleeding
- constant abdominal pain
- trapped gas
- lower back pain
- unintentional weight loss
Iron supplement safety
High doses of iron can be harmful and interact with medications. The daily upper limit of iron from all sources, which experts do not recommend exceeding, is
However, some people, such as those with hemochromatosis, should not take iron supplements. Therefore, people should consult a doctor before supplementing iron.
Some pregnant or nursing people take iron supplements under a doctor’s guidance. However, if they become constipated, they should seek further advice.
People may take iron to help treat iron deficiency anemia or to supplement their diet. However, oral iron supplements may cause or worsen constipation. Experts suggest that unabsorbed iron in the gut may cause stools to harden and other gastrointestinal side effects, such as pain and bloating.
A person should consult a doctor before supplementing iron or if they think they have constipation. Eating fiber, staying hydrated, and being physically active may help avoid constipation. A doctor may also recommend medications to soften stools or make bowel movements easier.