The best way to take iron pills to treat iron deficiency anemia is on an empty stomach or with a source of vitamin C. If you take iron supplements with caffeine, milk or antacids, your body will absorb less elemental iron.
Iron pills can cause nausea, in which case you can take them with a small snack or at mealtime.
Daily Iron Intake Recommendations
How much iron you need every day depends on your age and sex. According to the National Institutes of Health Office of Dietary Supplements, the recommended daily allowances (RDAs) for iron are:
- 11 milligrams per day for babies ages 7 to 12 months* 7 milligrams per day for toddlers ages 1 to 3 years
- 10 milligrams per day for children ages 4 to 8
- 8 milligrams per day for children ages 9 to 13
- 11 milligrams per day for men ages 14 to 18
- 15 milligrams per day for women ages 14 to 18
- 8 milligrams per day for men ages 19 to 50
- 18 milligrams per day for women ages 19 to 50
- 27 milligrams per day for pregnant people
- 9 to 10 milligrams per day for breastfeeding people* 8 milligrams per day for adults over 51 years of age
Who Needs Iron Supplements?
According to Harvard Health Publishing, 1 to 2 percent of Americans have iron deficiency anemia, a condition where your body doesn't have enough iron to help red blood cells transport oxygen. For the most part, people get the iron they need from their diet.
The most easily absorbed form of dietary iron is heme iron, which is attached to hemoglobin proteins. Heme iron is found in fish, red meat and poultry. Nonheme iron, which is not attached to a protein, is found in plant foods like leafy greens and beans.
Causes of iron deficiency anemia include:
- Blood loss
- Trouble absorbing iron (example: due to conditions like celiac disease or Crohn's disease)
- A diet low in iron
- Heavy periods
There are a number of symptoms of iron deficiency anemia, including:
- Feeling dizzy or lightheaded
- A swollen or sore tongue
- Feeling cold in your hands and feet
- Brittle nails
- Pica, which is when you have cravings for nonfood substances such as ice or dirt
- A fast heartbeat
- Shortness of breath
If you have iron deficiency anemia, your doctor may suggest you take over-the-counter iron supplements to boost the levels of iron in your body. It can take several months to replenish your iron stores, so your doctor can advise you on how long you should take iron pills. The best way to take iron pills depends on whether you experience side effects.
How to Take Iron Supplements
According to the Cleveland Clinic, taking iron in two or more doses during the day is the best way to absorb the greatest amount. There are a few other guidelines you can follow, too.
- Take iron supplements on an empty stomach. The University of Rochester Medical Center states that taking iron supplements on an empty stomach will help increase the amount of elemental iron your body absorbs.
- Take vitamin C with iron supplements to help you absorb more elemental iron. According to the Linus Pauling Institute at Oregon State University, vitamin C "strongly enhances" absorption of nonheme iron. MedlinePlus suggests drinking a small glass of orange juice or taking a vitamin C supplement at the same time that you take your supplemental iron.
- Don't take iron pills with antacids. The Mayo Clinic notes that antacids can interfere with iron absorption, so if you're planning to take antacids, take your iron supplements two hours before antacids, or two hours afterward.
- Milk and caffeine interfere with iron pills. The National Institutes of Health Office of Dietary Supplements explains that calcium (found in milk) can reduce nonheme and heme iron bioavailability. And, according to the Linus Pauling Institute, phenolic compounds found in coffee and tea bind to nonheme iron, making it more difficult for your body to absorb it. As such, you should avoid consuming caffeine an hour before or after taking your iron supplements.
- If you aren't at risk of iron deficiency anemia, you probably don't need a specific iron supplement. According to the Linus Pauling Institute, those who aren't at risk of iron deficiency — like adult men and postmenopausal women — shouldn't take iron supplements without medical evaluation.
Read more: Foods That Inhibit Iron Absorption
Do Iron Pills Cause Nausea?
Because iron pills can cause side effects like abdominal cramps, nausea and diarrhea, some people prefer not to take the supplements on an empty stomach. In that case, you can take iron supplements with a small amount of food.
For a study in the June 2019 issue of the journal Gut, researchers investigated the effects of iron supplements on 336 subjects who had iron deficiency anemia. Each participant was given 200 milligrams of oral ferrous sulphate twice a day. Almost 67 percent of participants had darkened stools, 20 percent had diarrhea, over 20 percent had constipation and, for over 11 percent, iron pills caused nausea.
Read more: Side Effects of Iron Tablets
How Much Iron to Take
According to the American Society of Hematology, people with iron deficiency anemia should take iron pills containing 150 to 200 milligrams of elemental iron each day. The society also recommends chatting with your doctor about your iron supplement dosage if you already take a multivitamin that contains iron.
Iron in vitamins varies, depending on which age group and sex the multivitamin is created for. Typically, multivitamins for women of menstruating age will contain more elemental iron than multivitamins for men.
Read more: How Much Is Too Much Iron Supplement?
Experts recommend keeping iron supplements and vitamins with iron out of the reach of children, as too much iron can be toxic to kids. The University of Rochester Medical Center says that accidental iron overdoses are the No. 1 cause of poisoning in kids in the U.S., because vitamins containing iron often come as bright-colored tablets or gummies that can be mistaken for candy.
- Gut: "Assessment of Response and Tolerance to Oral Iron Supplements in Patients with Anaemia"
- Cleveland Clinic: "Oral Iron Supplementation"
- Oregon State University Linus Pauling Institute: "Iron"
- Harvard Health: "A Healthy Diet Is the Key to Getting the Iron You Need"
- MedlinePlus: "Taking Iron Supplements"
- Mayo Clinic: "Iron Deficiency Anemia"
- University of Rochester Medical Center: "Iron Deficiency Anemia"
- National Institutes of Health Office of Dietary Supplements: "Iron"
- The American Society of Hematology: "Iron-Deficiency Anemia"