Anemia

Anemia occurs when there aren’t enough healthy red blood cells in your body. Learn about anemia symptoms, causes, treatment, and more.

Introduction

Around three million people in the United States live with anemia, according to the Centers for Disease Control and Prevention (CDC). Anemia makes it difficult for your body to receive enough oxygen-rich blood, which can lead to symptoms like weakness and shortness of breath. Many cases of anemia are mild and easily treatable.

Learn the facts about anemia, why it happens, how it feels, and what you can do to treat this condition and feel better.

What is anemia?

View of man at his desk, eyes closed, holding his glasses with one hand and his head with the other, fatigued from anemia

Anemia occurs when your blood doesn’t have enough healthy red blood cells (RBCs). This is also called a low RBC count. A healthy RBC contains hemoglobin, which is an iron-rich protein that attaches to oxygen from the lungs and delivers it to tissues throughout the body. When there aren’t enough RBCs to transport this oxygen-rich blood—or, if RBCs aren’t functioning properly—you have anemia.

How common is anemia?

Anemia is the most common type of blood disorder. The World Health Organization (WHO) reports more than a half a billion people assigned female at birth between the ages of 15 and 49 have anemia, as well as 269 million children between the ages of 6 and 59 months globally. Anemia is estimated to affect up to one-third of the world’s population.

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What are the types of anemia?

There are many forms of anemia, each with its own causes and risk factors. Anemia can generally be classified as microcytic, macrocytic, or normocytic.

Microcytic anemia   

Microcytic anemia occurs when RBCs are smaller than they should be due to low levels of hemoglobin. The most common type of microcytic anemia—and anemia in general—is iron-deficiency anemia.  

Iron-deficiency anemia

As its name suggests, iron-deficiency anemia results from a lack of iron in the body. Iron is an essential mineral that fuels hemoglobin production.

There are several factors that can contribute to iron-deficiency anemia, including blood loss from gastrointestinal disorders, heavy menstrual periods, and traumatic injuries. Disorders that make it difficult to properly absorb iron may also lead to iron-deficiency anemia. These include conditions such as Crohn’s disease and ulcerative colitis, the two main types of inflammatory bowel disease (IBD). Additionally, iron-deficiency anemia can result from not consuming enough iron in your diet.

Macrocytic anemia    

Macrocytic anemia refers to blood disorders that occur when bone marrow—the spongy tissue in the center of most bones that contains blood-forming stem cells—creates RBCs that are abnormally big. Despite their size, these RBCs lack nutrients that are key to healthy function.

The most common cause of macrocytic anemia is a lack of vitamin B12 or factors that make it difficult for the body to properly absorb this nutrient, such as alcohol abuse, cancer, certain autoimmune diseases, and inflammatory bowel disease. Too little vitamin B9 (folate) and issues that prevent proper absorption can also lead to macrocytic anemia.

Vitamin B12-deficiency anemia

Also known as cobalamin deficiency, anemia due to vitamin B12 deficiency occurs when your body can’t produce enough healthy RBCs due to low vitamin B12 levels. In addition to helping your body make RBCs, this vitamin also supports the production of white blood cells and platelets (components of the blood that help it clot).

Vitamin B12-deficiency anemia can happen if you don’t eat enough vitamin B12-rich foods (such as meat and eggs) or if your body can’t properly absorb this vitamin. Common causes of poor vitamin B12 absorption include Crohn’s disease, ulcerative colitis, and pernicious anemia. Pernicious anemia occurs when the body doesn’t make a substance called intrinsic factor, which helps the intestines take in vitamin B12. Additionally, adults over age 50 may have less hydrochloric stomach acid, which plays a key role in dietary vitamin B12 absorption.

A lack of folate can also cause vitamin-deficiency anemia. Vitamin B12 and folate deficiencies may lead to megaloblastic anemia, a type of macrocytic anemia that occurs when your bone marrow makes abnormally large RBCs.

Normocytic anemia    

Normocytic anemia occurs when there are too few RBCs in the body and these cells don’t contain a healthy amount of hemoglobin. Examples of normocytic anemia include hemolytic anemia, sickle cell anemia, and aplastic anemia.  

Hemolytic anemia

Your body normally breaks down old or malfunctioning RBCs during a process called hemolysis. Hemolytic anemia can happen if too much hemolysis takes place in the body, which results in RBCs being destroyed faster than they can be produced. Problems like autoimmune diseases (when the immune system mistakenly attacks healthy cells), bone marrow failure, infections, and sickle cell disease may lead to hemolytic anemia. 

Sickle cell anemia

Sickle cell anemia is part of a group of inherited disorders called sickle cell disease. A healthy RBC is round and easily able to pass through blood vessels. In sickle cell anemia, RBCs are shaped like sickles or crescents and may become sticky and rigid, which can block blood flow through vessels. These RBCs may also die early and lead to a shortage of hemoglobin.

Aplastic anemia

An uncommon bone marrow disorder, aplastic anemia occurs when your body’s bone marrow fails to produce enough blood cells. Aplastic anemia can result from certain autoimmune diseases, viral infections, exposure to toxic chemicals, drugs, or cancer treatments like radiation therapy and chemotherapy. The exact cause of aplastic anemia is unknown in some cases. 

Anemia of chronic disease

Anemia of chronic disease (ACD)—also referred to as anemia of inflammation—may occur if an illness that causes inflammation lasts longer than three months. This inflammation can impact your body’s ability to properly use iron and produce enough healthy RBCs. Many people who have ACD are older than 65 and have cancer, heart failure, or an autoimmune disease such as rheumatoid arthritis. Being obese or having an infection may also lead to ACD.

Kidney disease is another common factor behind ACD. In addition to having low iron levels, people with kidney disease may not produce enough erythropoietin (EPO)—a hormone that helps the body make RBCs.

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What are the symptoms of anemia?

View of woman lying back on her couch with eyes closed, tired as a result of anemia

Anemia symptoms can vary from person to person. You may not experience any symptoms if your condition is mild or develops slowly. In general, the symptoms of anemia that may appear first include:

  • Weakness
  • Fatigue
  • Headache
  • Irritability
  • Loss of appetite
  • Cold or numb feet or hands 

If anemia progresses, symptoms may involve:

  • Irregular or fast heartbeat  
  • Shortness of breath
  • Pale or yellow skin (this may be less noticeable in people with darker skin tones)
  • Pulsatile tinnitus (a “whooshing” or pounding sound in your ears that comes and goes)
  • Easy bleeding and bruising
  • Dizziness, lightheadedness, or fainting 
  • Yellowing of the whites of the eyes
  • Chest pain

Less common symptoms of anemia include trouble sleeping, tongue swelling, anxiety, depression, and changes in fingernail texture and appearance.

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What causes anemia?

Anemia can occur if:

  • Sudden or gradual bleeding leads to a loss of RBCs and hemoglobin
  • Your body destroys RBCs and hemoglobin faster than they can be replaced
  • Your body doesn’t produce enough RBCs or hemoglobin

The precise cause of anemia will depend on which type you have. For example, iron-deficiency anemia results from a lack of iron, a mineral that’s essential to hemoglobin production.

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What are the risk factors for anemia?

Anemia has a wide range of risk factors, which are things that can increase your risk of developing the condition. Some notable anemia risk factors include:

Age: People over age 65 and children younger than 3 have an increased risk of anemia. Chronic conditions contribute to anemia in older adults, while many young children don’t consume enough iron-rich foods. In general, people assigned female at birth of childbearing age may be at higher risk for mild iron-deficiency anemia because of poor dietary intake of iron or dips in hemoglobin levels during their monthly periods.

Family history: You’re more likely to have anemia if someone in your family has a type of inherited anemia.

Blood loss: Losing a large amount of blood from factors such as sudden injury, surgery, or donating too much blood may lead to anemia. You can also gradually lose blood and develop anemia due to problems like heavy menstrual periods, stomach ulcers, or bleeding from the bowels related to colon cancer.

Dietary factors: Not consuming enough of certain vitamins and minerals—namely iron, vitamin B12, and folate—can increase your chances of anemia. Drinking alcohol in excess also raises your risk.

Pregnancy: Pregnant people have an elevated risk of iron-deficiency anemia. The amount of blood in a pregnant person’s body increases by up to 30 percent, which means more iron and vitamins are required to produce an adequate amount of hemoglobin.

Medication: Some drugs cause your immune system to mistakenly launch an immune response, prompting the production of immune system proteins called antibodies that bind to RBCs and destroy them too early. Cephalosporins (a class of antibiotics) are the most common cause of drug-induced anemia, along with nonsteroidal anti-inflammatory drugs (NSAIDs) and certain other medicines.

Small intestine issues: Conditions like Crohn’s disease and celiac disease can impact the small intestine’s ability to properly absorb certain nutrients, which can lead to anemia.

Certain diseases: Diseases like cancer, autoimmune disorders, and kidney disease can reduce the amount of healthy RBCs in the body and increase the risk of anemia.

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How is anemia diagnosed?

Closeup of a doctor's hands holding a blood vial and pen, explaining diagnosis of anemia

Anemia is usually diagnosed through a blood test, which may be ordered after your healthcare provider (HCP) assesses your condition and asks you questions about your symptoms and personal and family medical histories.  

The most common blood test to evaluate overall health and diagnose anemia is called a complete blood count (CBC). This test measures:

  • RBC levels
  • Mean corpuscular volume (a measure of the average size of RBCs)
  • Hematocrit levels (the percentage of RBCs in your blood)
  • Hemoglobin levels

Normal adult hemoglobin levels are around 13.5 to 18 grams per deciliter for people assigned male at birth and 12 to 15 grams per deciliter for people assigned female at birth . In children, hemoglobin levels should be between 11 and 16 grams per deciliter.

Healthy hematocrit ranges are usually between 40 to 52 percent in people assigned male at birth and 35 to 47 percent for people assigned female at birth.

Other diagnostic tests for anemia

Your HCP may also want to evaluate the health of your bone marrow, which is where RBCs are made. To do this, a fine-needle aspiration procedure is performed to draw out a small amount of bone marrow fluid for testing. Bone marrow aspiration involves inserting a thin needle into a bone (usually the back of the hipbone) to collect fluid. The procedure only takes a few minutes and is typically performed using a sedative or local anesthesia.

Based on the results of the fine-needle aspiration, bone marrow tissue may also be collected from the bone with a larger needle during a biopsy. This sample can provide information about the causes of abnormal red blood cell counts and help guide treatment recommendations.

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What are the possible complications of anemia?

The complications of anemia can vary based on its type. Generally speaking, the most common complications of anemia include:

  • Severe fatigue that can make it difficult to perform routine tasks
  • Pregnancy complications, including increased blood loss during delivery, premature birth, low birthweight, and an increased risk of anemia and developmental delays in the baby
  • A lack of oxygen-rich blood in vital organs that can lead to problems like enlarged heart, irregular heartbeat, and kidney disease
  • Death, if potentially life-threatening anemias (such as sickle cell anemia) are poorly managed

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When should you see a healthcare provider for anemia?

It’s always a good idea to speak with your HCP if you notice possible symptoms of anemia, especially if you frequently feel short of breath. The National Heart, Lung, and Blood Institute recommends that people who have menstrual periods consult with an HCP if:

  • They experience periods that last longer than seven days
  • Heavy bleeding requires them to change their pad or tampon after less than two hours
  • Passed clots are the size of quarters or larger

What happens if anemia isn't treated?

Untreated or poorly managed iron-deficiency anemia may worsen existing health conditions and lead to problems like headaches, fatigue, and even restless leg syndrome.

No matter what type of anemia you have, it’s important to prioritize your health and take steps to manage your condition. Untreated anemia can cause life-threatening complications in some cases. If poorly managed, aplastic anemia and hemolytic anemia can lead to heart failure.

When should I go to the emergency room?

Severe anemia may cause symptoms that require emergency care. Call 911 or go to the nearest emergency room if you experience any of the following:

  • Chest pain
  • Loss of consciousness
  • Trouble breathing

An injury with heavy bleeding that persists after applying direct pressure 

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How is anemia treated?

Closeup of supplement capsules for treating anemia

Your best course of anemia treatment will depend on your overall health and what type of anemia you have. Addressing the underlying cause of anemia—such as a stomach ulcer—may effectively treat anemia in some cases. Your HCP might refer you to a hematologist, a physician who specializes in evaluating and treating blood disorders like anemia.

Medications for anemia

Anemia related to an autoimmune disease is sometimes treated with immunosuppressant or corticosteroid medications that calm the immune system, such as prednisone. In other cases, a medicinal form of erythropoietin that helps bone marrow produce more blood cells may be recommended.  

In February 2023, the Food and Drug Administration approved the first oral EPO medication (daprodustat) to treat anemia caused by chronic kidney disease. Prior to this medication, shots were administered to stimulate EPO production in people with kidney disease.

Supplements for anemia  

People with mild or moderate anemia from iron or vitamin deficiencies may benefit from taking supplements. Depending on the cause of your anemia, your HCP may recommend taking iron, vitamin B12, or vitamin B9 supplements. You can find these nutrients in many multivitamins, B-complex supplements, and single-nutrient supplements. Just be sure to read the nutrition label to see exactly what and how much you’re taking.

A surplus of iron may lead to organ damage, so you should consult with your HCP before starting a supplement regimen for iron-deficiency anemia. An overdose of vitamin B12 can cause headaches and nausea and excessive vitamin B9 intake may result in tremors and nervousness, although consuming too much of a particular vitamin is uncommon.

Other treatments for anemia  

Blood transfusion

A blood transfusion is a common medical procedure in which a person receives healthy blood (and healthy RBCs) through an intravenous (IV) line inserted into the arm to raise hemoglobin and oxygen levels. The blood is provided by a donor with a matching blood type.  

Intravenous iron

IV iron supplementation, or an iron infusion, delivers iron directly to the bloodstream

through a small needle inserted into a vein. A person may need several rounds of treatment to achieve healthy iron levels and reverse anemia.

Bone marrow transplant  

A bone marrow transplant may be the only cure for aplastic anemia in severe cases. Also called a stem cell transplant, this procedure replaces malfunctioning blood-forming stem cells with healthy ones.

Treatment starts with chemotherapy or radiation therapy to destroy unhealthy stem cells and immune cells that would otherwise target the newly transplanted stem cells. Healthy stem cells from a carefully matched donor are then administered intravenously and travel to the bone marrow to stimulate RBC growth.

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Can you prevent anemia?

Nutritional anemias like iron-deficiency anemia can be prevented by eating a healthy, varied diet. You may also want to ask your HCP about taking a multivitamin. Less common types of anemia, like hemolytic anemia and aplastic anemia, aren’t preventable. If you have a chronic condition that puts you at a higher risk of anemia (such as kidney disease), you should carefully follow your HCP’s treatment guidance and promptly report any signs of anemia.

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What is the outlook for anemia?

Many cases of anemia are easily treated. Still, anemia related to a chronic condition may become a lifelong issue. If you have anemia, it’s important to prioritize your nutrition and carefully follow your HCP’s treatment guidance. Properly managing your anemia (or its underlying cause) can help you keep symptoms in check, avoid complications, and enjoy an active, healthy lifestyle.

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Living with anemia

Spread of vegetarian foods that are a rich source of iron for people with anemia

Anemia symptoms like fatigue, headaches, and shortness of breath can take a toll on your physical health and as well as your emotional well-being. If living with anemia has left you feeling frustrated, anxious, or depressed, consider sharing your thoughts with a trusted friend or family member. Attending online or in-person support groups may also be helpful, as can speaking with a licensed mental health provider.

If your anemia symptoms persist or worsen—or, if they begin to impact your mental health—it’s important to inform your HCP as quickly as possible. Your HCP can provide individualized care recommendations and help you achieve your best quality of life.

Daily nutritional requirements and anemia

Proper nutrition is important for everyone. Still, people with anemia should be particularly mindful about consuming enough iron, folate (vitamin B9), vitamin B12, and vitamin C.  

Iron

How many milligrams (mg) of iron you need each day depends on your age and whether you were assigned male or female at birth. The National Institutes of Health recommends:

  • 0.27 mg for babies from birth to 6 months
  • 11 mg for infants ages 7 to 12 months
  • 7 mg for children ages 1 to 3 years
  • 10 mg for children ages 4 to 8
  • 8 mg for children ages 9 to 13
  • 11 mg for males ages 14 to 18  
  • 15 mg for females ages 14 to 18  
  • 8 mg for males ages 19 to 50
  • 18 mg for females ages 19 to 50 mg
  • 8 mg for adults age 51 and older
  • 27 mg for pregnant people  
  • 9 to 10 mg for breastfeeding people

If you follow a vegetarian diet and don’t eat meat, seafood, or poultry, you should try to consume almost twice as much iron as what’s listed above. This is because the body doesn’t absorb iron from plant sources as well as it does from animal sources. Keep in mind that adults shouldn’t exceed 45 mg of iron per day, and kids 13 and younger should keep their daily intake under 40 mg.

Iron can be found in a variety of foods and supplements, including:

  • Nuts and certain dried fruits, like raisins
  • Lean red meat, poultry, and seafood
  • Spinach, peas, white beans, kidney beans, and lentils
  • Iron-fortified breads and cereals

Folate (vitamin B9)

Age and pregnancy are the two biggest factors that influence recommended daily folate intake, which is measured in micrograms (mcg) of daily folate equivalents (DFE). This is because folic acid (a type of folate that’s used in supplements and fortified foods) is better absorbed by the body than folate found naturally in foods. So, 240 mcg of folic acid and 400 mcg of folate both equate to 400 mcg DFE. 

The NIH recommends the following daily amount of folate:

  • 65 mcg DFE for babies from birth to 6 months
  • 80 mcg DFE for infants ages 7 to 12 months
  • 150 mcg DFE for children ages 1 to 3 years
  • 200 mcg DFE for children ages 4 to 8
  • 300 mcg DFE for children ages 9 to 13
  • 400 mcg DFE for people age 14 and older 
  • 600 mcg DFE for pregnant people
  • 500 mcg DFE for breastfeeding people

Folic acid—which is used in supplements and some fortified breads and cereals—can also help prevent neural tube defects when taken before and during the early stages of pregnancy.

Folate is found naturally in foods like:

  • Fruits and fruit juices, including oranges and orange juice
  • Beef liver
  • Nuts and beans, including kidney beans, black-eyed peas, and peanuts
  • Vegetables like peas, asparagus, Brussels sprouts, and dark leafy greens like spinach  

Vitamin B12  

How many micrograms (mcg) of vitamin B12 you should consume in a day largely depends on your age. The NIH recommends the following daily amounts:

  • 0.4 mcg for babies from birth to 6 months
  • 0.5 for infants ages 7 to 12 months
  • 0.9 mcg for children ages 1 to 3 years
  • 1.2 mcg for children ages 4 to 8
  • 1.8 mcg for children ages 9 to 13
  • 2.4 mcg for people age 14 and older
  • 2.6 mcg for pregnant people
  • 2.8 mcg for breastfeeding people

Vitamin B12 is found naturally in animal products like:

  • Meat, poultry, fish, and eggs
  • Beef liver and clams
  • Milk and other dairy products

You can also reach your daily dose of vitamin B12 through supplements and certain fortified cereals and nutritional yeasts. Vitamin B12 may be referred to as cyanocobalamin, adenosylcobalamin, methylcobalamin, or hydroxycobalamin in certain supplements and foods.  

Vitamin C

Also known as ascorbic acid, vitamin C is a water-soluble nutrient that boosts your body’s ability to absorb dietary iron. How many milligrams (mg) of vitamin C you should consume in a day will depend on your age. The NIH recommends the following:

  • 40 mg for babies from birth to 6 months
  • 50 mg for infants ages 7 to 12 months
  • 15 mg for children ages 1 to 3 years
  • 25 mg for children ages 4 to 8
  • 45 mg for children ages 9 to 13
  • 75 mg for teen males ages 14 to 18
  • 65 mg for teen females ages 14 to 18
  • 90 mg for males age 19 and older
  • 75 mg for females age 19 and older 
  • 85 mg for pregnant people
  • 120 mg for breastfeeding people

People who smoke cigarettes should add an extra 35 mg to the above recommended daily values.

Vitamin C can be found in a wide range of fruits and vegetables, including citrus fruits and their juices, red and green peppers, kiwis, broccoli, strawberries, tomatoes, cantaloupe, and even baked potatoes.

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Featured anemia articles

Topic page sources
open topic sources

American Society of Hematology. Anemia. Accessed May 15, 2023.   

American Society of Hematology. Anemia and Pregnancy. Accessed May 16, 2023.  

Aplastic Anemia & MDS International Foundation. Bone Marrow and Stem Cell Transplantation. Accessed May 22, 2023.

Centers for Disease Control and Prevention. Anemia or Iron Deficiency. Last reviewed January 17, 2023.   

Cleveland Clinic. Anemia. Last reviewed September 12, 2022.  

Cleveland Clinic. Anemia of Chronic Disease. Last reviewed April 7, 2022.

Cleveland Clinic. Intravenous Iron Supplementation. Last reviewed July 17, 2019.  

Cleveland Clinic. Macrocytic Anemia. Last reviewed May 16, 2022.

Cleveland Clinic. Megaloblastic Anemia. Last updated May 27, 2022. 

Cleveland Clinic. Microcytic Anemia. Last updated May 16, 2022

Cleveland Clinic. Normocytic Anemia. Last reviewed May 10, 2022.

Mayo Clinic. Anemia. Last updated May 16, 2023.    

Mayo Clinic. Bone Marrow Biopsy and Aspiration. Last updated December 1, 2022.

Mayo Clinic. Sickle Cell Anemia. Last updated March 9, 2022.

MedlinePlus. Anemia. Last reviewed January 25, 2022.

MedlinePlus. Drug-Induced Immune Hemolytic Anemia. Accessed May 17, 2023.  

Merck Manual. Autoimmune Hemolytic Anemia. Last modified September 2022.  

National Heart, Lung, and Blood Institute. Anemia Causes and Risk Factors. Last updated March 24, 2022.

National Heart, Lung, and Blood Institute. Anemia Diagnosis. Last updated March 24, 2022.  

National Heart, Lung, and Blood Institute. Anemia in Pregnancy. Last updated March 24, 2022.

National Heart, Lung, and Blood Institute. Anemia Symptoms. Last updated March 24, 2022.    

National Heart, Lung, and Blood Institute. Hemolytic Anemia. Last updated March 24, 2022.

National Heart, Lung, and Blood Institute. Iron-Deficiency Anemia. Last updated March 24, 2022.

National Heart, Lung, and Blood Institute. Vitamin B12-Deficiency Anemia. Last updated March 24, 2022.

National Heart, Lung, and Blood Institute. What is Anemia? Last updated March 24, 2022.   

National Institutes of Health. Folate Fact Sheet for Consumers. Last updated November 1, 2022. 

National Institutes of Health. Iron Fact Sheet for Consumers. Last updated April 5, 2022. 

National Institutes of Health. Vitamin B12 Fact Sheet for Consumers. Last updated July 21, 2021.

National Institutes of Health. Vitamin C Fact Sheet for Consumers. Last updated March 22, 2021.

Penn Medicine. What is Anemia? Last reviewed January 25, 2022.  

Turner J, Parsi M, Badireddy M. Anemia. StatPearls [Internet]. Last updated August 8, 2022.

U.S. Food and Drug Administration. FDA Approves Oral Treatment for Anemia Caused by Chronic Kidney Disease for Adults on Dialysis. Published February 1, 2023.

World Health Organization. Anaemia. Accessed May 15, 2023.

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