In most cases, healthy people do not need to take an iron supplement to ensure an adequate intake of iron, but certain groups of people are more likely to need one. Most pregnant women are prescribed an iron supplement in the amount of 30 milligrams (mg) each day until the birth of the baby. Anyone with one or more of the following conditions may also need an iron supplement:
- Women with heavy menstrual periods
- Bleeding problems
- Intestinal diseases
- Stomach problems
- Removal of stomach or intestines
If your health-care provider recommends an iron supplement for you, chances are it will be in the form of ferrous sulfate, ferrous gluconate, or ferrous fumarate. Ferrous sulfate is more readily absorbed but is more likely to cause gastrointestinal distress and constipation. In that case, you may be advised to switch to ferrous gluconate, which is less irritating to the digestive tract (although it is not as readily absorbed by the body).
Iron supplements are generally sold over the counter at drugstores and come in several forms, including capsules, tablets, and liquids. Iron is also available by injection (given by a health-care provider). People who have difficulty absorbing iron from food or supplements or who have stomach problems may need iron injections.
Possible side effects from iron supplements include the following:
- Upset stomach
- Dark-colored stools
- Dark-colored urine
- Leg cramps
- Stained teeth (from liquid supplements)
Some of these side effects, such as upset stomach and constipation, are relatively common. Taking iron with food or immediately after eating can help lessen stomach upset, and increasing fiber and fluid intake may help prevent constipation. Dark green or black stools are normal and occur due to unabsorbed iron. (However, you should call your health-care provider if your stools are dark with a sticky consistency, or if you see red streaks, and if you have any abdominal cramping or pain because these can indicate serious gastrointestinal bleeding.)
Unless you have a chronic condition that impairs iron absorption, iron supplements are not meant to be taken indefinitely, so pay attention to your health-care provider’s instructions as to how long you should take your supplement. If you are anemic, for example, you may need to take an iron supplement for up to six months until the anemia resolves.
Iron supplements may interact or interfere with the absorption and action of some medicines. In addition, taking iron can worsen other medical conditions, such as kidney disease, heart disease, asthma, intestinal disorders, and stomach ulcers. Once again, it’s important to discuss taking iron supplements with your health-care provider, especially if you have any health concerns.
Certain foods decrease iron absorption when taken with an iron supplement, such as dairy foods, eggs, spinach, whole-grain products, tea, and coffee. Either take your iron one hour before eating these foods, or wait a couple hours after eating them. Don’t take your iron with calcium supplements and antacids. (Remember, to increase iron absorption from food and supplements, eat a food high in vitamin C with your meal, such as an orange, a tomato, strawberries, or green pepper.)
Store iron supplements away from heat and light, and discard any expired supplements. Always keep iron out of the reach of children, because an iron overdose can be fatal. Because of this risk, expired iron supplements should be discarded in a way that keeps them away from curious children such as flushing them down the toilet. If you suspect a child has taken too much iron, call the Poison Control Center at (800) 222-1222 or take the child to the nearest emergency room.