Iron Deficiency Anemia

Medically Reviewed by Jabeen Begum, MD on February 23, 2024
11 min read

Iron deficiency anemia is when your body doesn’t have enough red blood cells.

Red blood cells carry oxygen from your lungs to the rest of your body. Every organ and tissue in your body needs oxygen to work. Without enough oxygen in your blood, you may feel tired, weak, and short of breath.

You get iron deficiency anemia when your body is low in iron. You need iron to make hemoglobin, a protein that helps your red blood cells carry oxygen.

Your doctor will find out why your iron is low. Usually, you can treat iron deficiency anemia with supplements. Once your iron levels go up, you should start to feel better.

There are three stages of iron deficiency anemia:

  • First stage. In the first stage, the iron that your body is taking in is less than what your body needs. Your iron stores that are needed to make new hemoglobin and red blood cells are being used up, but your red blood cells are not yet affected.
  • Second stage. In the second stage, you develop iron-deficient erythropoiesis during which your bone marrow makes red blood cells, but without enough hemoglobin.
  • Third stage. In the third stage, your hemoglobin levels will be below the normal range because you don't have enough iron to make hemoglobin. Your symptoms of iron deficiency anemia would begin at this stage.

Mild iron deficiency anemia often isn't noticeable. When it gets more severe, you may have these symptoms of low iron:

Because these can also be symptoms of other conditions, see your doctor to get a diagnosis.

It can happen if you don't eat enough foods containing iron, if your body can't properly absorb iron, if you lose iron through your blood, or if you’re pregnant.

Low-iron diet. How much iron you need depends on your age and sex. Men or people assigned male at birth (AMAB) need at least 8 milligrams daily. Women or people AFAB ages 50 and younger need more -- 18 milligrams.

If you're pregnant, your iron storage has to provide hemoglobin to your baby and help with the increased amount of blood you have throughout your pregnancy. This can cause iron deficiency anemia. 

Also, babies and young children may become iron deficient if they were born prematurely or with a low birth weight and don't get enough iron from breast milk, formula, or foods. Children also need more iron while they're growing and need to eat a variety of foods.

Your body can't absorb iron. Iron from the foods you eat is absorbed in your small intestine. Conditions such as celiac disease, ulcerative colitis, or Crohn's disease can make it harder for your intestines to absorb iron from the foods you digest. Surgery such as gastric bypass, which removes part of your intestines, and medicines used to lower stomach acid can also affect your body's ability to absorb iron.

Blood loss. Some conditions can make you bleed inside your body, including:

Blood loss can lead to iron deficiency anemia because blood holds iron within red blood cells. The more blood you lose, the more iron you lose.

Heavy periods. Women with heavy periods can become low in iron because they lose blood during their cycle. Heavy periods mean losing blood over a longer period, which can reduce your storage of iron. This iron loss also happens if you have endometriosis, a condition where tissue grows outside of the uterus and can cause heavy bleeding during your period.

Injuries. Any injury that causes you to lose blood can cause iron deficiency anemia.

Frequent blood donations. Giving blood often can remove iron from your body. If you donate more than 2-3 units a year, you're considered a frequent blood donor. Taking an iron supplement or a multivitamin that contains iron may help you boost iron lost from donations.

Pregnancy. When you’re expecting, you need extra iron to nourish your growing baby as well as provide enough for you and the increase in your blood volume. If you don't get enough iron from your diet or supplements, you can become deficient.

End-stage kidney failure. If your kidneys aren't working the right way, they can't make erythropoietin, a hormone made by kidneys that helps with producing red blood cells. Having fewer red blood cells affects the ability to carry oxygen throughout your body, which can lead to anemia.

Also, if you're getting dialysis for end-stage kidney failure, you can lose blood. Some people with end-stage kidney failure also take medications that can cause iron-deficiency anemia.

Medications. Aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs) can cause internal gastrointestinal bleeding. Proton pump inhibitors, used to control acid reflux, can prevent your body from absorbing enough iron.

One study showed that taking a mix of histamine-2 receptor antagonists, proton pump inhibitors, and calcium carbonate can also lead to iron deficiency anemia, but more research is needed.

Chronic health conditions that cause inflammation. People who have certain long-term conditions involving inflammation can develop anemia of chronic disease (ACD). Some chronic conditions that lead to ACD are:

  • Cancer, including Hodgkin's disease and lymphoma
  • Autoimmune conditions such as rheumatoid arthritis, lupus, ulcerative colitis, and Crohn's disease
  • Long-term infections including HIV/AIDS, hepatitis B, hepatitis C, or osteomyelitis (a bone infection)

Anemia can lead to a higher risk of death if you have congestive heart failure.

Genetics. A rare condition called iron-refractory iron deficiency anemia is a form of anemia that you can inherit from your parents. Babies with this condition are born with a gene mutation that causes low iron.

Congenital dyserythropoietic anemia is a blood disorder that you can inherit that affects your body's ability to make red blood cells, which also can lead to anemia.

What conditions make it hard for my body to absorb iron?

Other conditions that can affect your body's ability to absorb iron include:

  • An intestinal or digestive condition such as autoimmune gastritis or inflammatory bowel disease
  • A bacterial infection of your stomach
  • Any previous gastrointestinal surgery

Different factors can raise your risk of getting iron deficiency anemia. Some can be changed and some cannot. Risk factors include:

  • Age. Children ages 6 months to 2 years, teens, and adults over the age of 65 are most at risk.
  • Lifestyle. This can include exercising a lot (including endurance sports) and not eating enough foods rich in iron.
  • Lead. Lead from water or environmental sources can get in the way of making red blood cells.
  • Family history and genetics. Two inherited diseases, hemophilia and von Willebrand disease, can cause you to bleed more and lose iron.
  • Gender. Girls and women who have heavy periods or are pregnant or breastfeeding need more iron.
  • Infants and children. Infants who are only breastfed or who drink formula that's not fortified can get anemia. Those who drink a lot of cow's milk also develop it.

Why is iron deficiency anemia more common in women? It's because of blood loss during the menstrual cycle. Being pregnant and having a child can also cause iron deficiency anemia.

Your doctor will do one or more of these blood tests to find out if you have iron deficiency anemia.

  • Complete blood count (CBC) and mMean cellular volume (MCV) blood tests.   A CBCchecks to see how many red blood cells you have. An MCV confirms the average size of your red blood cells and is included with the CBC test.
  • Peripheral blood smear. This test looks at the size and shape of your red blood cells. In iron deficiency anemia, red blood cells are smaller than usual.
  • Hematocrit. This test shows how much of your blood is made up of red cells.
  • Hemoglobin. This test shows the amount of this protein in your blood. If you have anemia, your hemoglobin will be low.
  • Serum iron. This test shows how much iron is in your blood.
  • Ferritin. This test shows how much iron is stored in your body by measuring this protein.
  • Transferrin and total iron-binding capacity (TIBC). These tests show how much of a protein called transferrin is free to carry iron through your body.
  • Reticulocyte count. This test shows how many reticulocytes (immature red blood cells) you have in your blood. If you have iron deficiency anemia, your reticulocyte count is usually low because you’re not making many new red blood cells.


If blood tests show you have iron deficiency anemia, you might need other tests to see what's causing it. These tests include:

  • Endoscopy. Your doctor uses a tube with a camera on one end to look inside your esophagus or colon. Endoscopy can find bleeding in your GI tract from ulcers, polyps, or other growths.
  • Pelvic ultrasound or uterine biopsy. If you bleed a lot during your monthly periods, this test can find the cause.
  • Fecal occult blood test. This test looks for tiny amounts of blood in your poop to check for cancer and other causes of bleeding in your intestines.
  • Urine test. Your doctor may recommend a urine test to see if hemoglobin or blood is in your pee.

Your doctor may treat your iron deficiency anemia in different ways.

Iron supplements. Most people take 150-200 milligrams each day, but your doctor will recommend a dose based on your iron levels. Taking vitamin C helps your body absorb the iron.

You might need to take iron supplements for a few months or more to get your levels to normal. If your intestines don't absorb iron well, you can take iron straight into your bloodstream through an intravenous tube (IV).

But be warned: Iron supplements can cause constipation, nausea, vomiting, diarrhea, heartburn, and dark-colored poop.

Your symptoms should start to go away after about a week. Your doctor will check your blood to see if your anemia has improved.


You can also get more iron in your diet by eating more of these foods:

  • Beef, pork, liver, chicken, turkey, duck, and shellfish
  • Leafy greens such as broccoli, kale, turnip greens, and collard greens
  • Peas, lima beans, black-eyed peas, and pinto beans
  • Iron-enriched cereals and other grains
  • Dried fruits, such as prunes and raisins

Eating foods high in iron may also prevent anemia.

Transfusion or other procedures

If supplements don't help with your symptoms or your anemia is severe, you might need a transfusion of red blood cells. Or, if you have an ulcer, tumor, or other growth, it may need to be treated with medicines or surgery.

If you don’t know you have iron deficiency anemia or if you know you have it but aren’t getting the right treatment, you could end up with complications such as:

  • Depression.
  • A higher risk of infection. This is because your immune system may not be working properly.
  • Problems with pregnancy. This can include preterm delivery and low-birth-weight babies.
  • Heart problems. Without enough red blood cells, your heart has to pump harder to get enough nutrients to the rest of your body. This causes strain, which can lead to heart failure, irregular heartbeat, an enlarged heart, or a heart murmur.
  • Developmental and growth delays in children. This can include cognitive problems and motor problems.

If you have iron deficiency anemia, it's usually because you're losing blood or not taking it in from the foods you eat. Talk to your doctor about ways you can prevent anemia.

Eating foods rich in iron could help. Some good sources of iron include:

  • Meat, including chicken and turkey, red meat, and pork
  • Seafood
  • Legumes
  • Cereals and breads
  • Certain fruits and leafy green vegetables

    Your body takes in more iron from meats than from other foods and sources. If you do not eat meat, including plant-based foods that are rich in iron in your diet can prevent iron deficiency anemia.

    Also, eating foods that are high in vitamin C while eating iron-rich foods can help. Vitamin C helps your body absorb iron better. Some foods high in vitamin C include citrus fruits, vegetables like broccoli and leafy greens, and strawberries, tomatoes, and peppers.

    Anemia prevention in infants and children

    For the first year of life, babies can get iron from breast milk or formula with iron added. Pureed meats and iron-fortified cereals can help with iron intake starting at 6 months old. When your baby is a year old, drinking no more than 20 ounces of milk daily is key, as too much milk can replace other foods like those high in iron.

Iron deficiency anemia happens when you don't take in enough iron from food you eat or your body loses iron. Talk to your doctor if you have any symptoms of iron deficiency anemia, which can include fatigue or weakness, hair loss, fast heartbeat or brittle nails. Some treatment options include iron supplements or infusion, or eating foods rich in iron.

  • What are the 4 main causes of iron deficiency anemia? The main causes of iron deficiency anemia are losing blood, having a diet low in iron, being pregnant, and being unable to absorb iron.
  • What are the stages of iron deficiency anemia? There are 3 stages of iron deficiency anemia. In the first stage, the iron that your body is taking in is less than what your body needs, but your red blood cells are not yet affected. In the second stage, you develop iron-deficient erythropoiesis during which your bone marrow makes red blood cells, but without enough hemoglobin. In the third stage, your hemoglobin levels will be below the normal range because you don't have enough iron to make hemoglobin. Your symptoms would begin at this stage.
  • Can you fix iron deficiency anemia? You can increase your iron levels by eating iron-rich foods or taking an iron supplement or getting an iron infusion. Talk to your doctor about the best option for you.
  • What is the difference between iron deficiency and anemia?  Iron deficiency is having low iron storage in your body that don't meet the level that your body needs. Iron-deficiency can cause anemia, which occurs when your body doesn't have enough iron to make healthy red blood cells or hemoglobin. You can have iron deficiency without being anemic, where your hemoglobin level is normal but your iron is low.