Common Side Effects of Iron Supplements for Anemia

Iron supplements may cause side effects you were unaware of

Woman in bathrobe taking medication in bathroom
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Women need more iron than men, so iron supplements, also known as ferrous sulfate, and its side effects, may be a fact of life for many women. Women between the ages of 19 and 50 need more than double the amount of iron men need: 18 mg a day vs. just 8 mg for men. When starting iron supplements you may experience upset stomach, constipation or even nausea and vomiting. These side effects of iron supplements are not new.

Here's what you should know about them, warning signs that something more serious is on the horizon, and how to prevent side effects as much as possible.

All About Iron Supplements

There are two types of iron supplements. They are ferrous and ferric. Because Ferrous iron is better absorbed by the body, and contains more elemental iron(33%), it is the preferred iron supplement. The three forms of ferrous iron are ferrous sulfate, ferrous fumarate and ferrous gluconate. The typical dosage of iron supplements is 325 mg. The severity of your anemia will determine your dosage for iron supplements. Your doctor may prescribe anywhere between 60 and 200 mg of elemental iron a day. That would make anywhere from 2-3 pills a day.

Warning Signs and Prevalence of Abdominal Irritation for Iron Supplements

It is estimated up to a quarter of anemic people who take iron supplements experience digestive tract side effects, such as an upset stomach and/or constipation.

While heavy menstrual periods is one of the leading causes of anemia, there are other reasons such as internal bleeding, that are not due to iron-deficiency. If you experience tarry and/or blood-streaked stools, sharp abdominal pains, soreness and cramps, your anemia may be due to a more serious condition.

Seek out a doctor immediately.

How to Prevent Iron Supplement Side Effects

Once you've determined that your anemia is due to iron-deficiency and not something more serious, you can try methods that will help alleviate the side effects of iron supplementation. You may find that you can diminish the digestive tract upset by starting with a smaller dose and gradually working your way up to a full dose of iron supplements in addition to taking it before meals. Also, it's important to take iron pills prior to eating, over an hour before eating should work. For those who experience constipation when using iron supplements, stool softeners may help relieve the constipation. Here are five other ways to prevent the common side effects of iron supplements:

  1. Drink a full glass of water or orange juice with the pill. The vitamin C in orange juice is said to boost absorption. The water just helps disperse the iron for better absorption.
  2. Take any medications at least 2 hours removed from iron tablets. The drugs may interact or prevent absorption of the iron pills.
  1. Avoid calcium around the time you take your iron supplements.
  2. Keep tablets in a cool place, preferably in a kitchen cabinet, rather than the bathroom.
  3. Remember iron supplementation is a long-term commitment. Up to 6 months after you start treatment you may have to take iron supplements to maintain your recovery from anemia.


Anemia Basics. National Anemia Action Council. .

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