Patient Basics: Sickle Cell Anemia (Sickle Cell Disease)

Sickle cell anemia is an inherited blood disorder in which red blood cells turn stiff and curved, like a crescent moon or a farm tool called a sickle. These cells die early, which causes anemia, and they can get stuck in small blood vessels, which causes sudden bouts of severe pain and can damage organs. It is the most common and usually the most serious type of sickle cell disease. Every US state tests newborns for it, and early care and newer treatments have greatly improved the outlook.

Key points

• A child gets sickle cell anemia by inheriting a sickle cell gene from each parent.
• People with one sickle cell gene have sickle cell trait. They usually have no symptoms but can pass the gene on.
• Newborn screening and a blood test called hemoglobin electrophoresis show whether someone has the disease or the trait.
• Fever, chest pain, trouble breathing and stroke signs are emergencies.
• Hydroxyurea, transfusions and good pain care help. A stem cell transplant or gene therapy can cure some people.

What causes sickle cell anemia

Red blood cells carry oxygen using a protein called hemoglobin. People with sickle cell anemia have a changed form called hemoglobin S. After it gives up its oxygen, hemoglobin S clumps into long strands that bend the cell out of shape. Normal red blood cells are soft and round and last about 120 days. Sickle cells are stiff and sticky and last only 10 to 20 days. The body can’t replace them fast enough, so the red blood cell count stays low.

How it is inherited

• Two sickle cell genes, one from each parent, cause sickle cell anemia.
• One sickle cell gene and one normal gene cause sickle cell trait.
• When both parents have the trait, each pregnancy has a 1 in 4 chance of a child with sickle cell anemia, a 1 in 2 chance of a child with the trait, and a 1 in 4 chance of neither.

Other forms of sickle cell disease happen when a person inherits one sickle cell gene plus a different changed hemoglobin gene, such as hemoglobin C or beta thalassemia.

Sickle cell disease affects about 100,000 people in the US. It is most common in people whose families come from Africa, but it also affects people with roots in Latin America, the Caribbean, the Middle East, India and the Mediterranean.

Sickle cell anemia symptoms

Symptoms usually start around 5 or 6 months of age, as babies switch from the hemoglobin they had before birth to the adult kind.

• Pain crises. Sudden, often severe pain in the bones, back, chest or belly. It can last hours to days. Cold, dehydration, infection, stress and high altitude can trigger it.
• Anemia. Tiredness, pale skin and shortness of breath.
• Yellow eyes or skin (jaundice), from the fast breakdown of red blood cells.
• Swollen hands and feet in babies and toddlers. This is often the first sign.
• Frequent or serious infections. Sickle cells damage the spleen, which normally helps fight certain bacteria.
• Slow growth and late puberty.

Serious complications

• Acute chest syndrome: chest pain, fever, cough and trouble breathing caused by sickling in the lungs
• Stroke, even in young children
• Splenic sequestration: blood pools in the spleen, causing a swollen belly, weakness and pale skin
• Priapism: a painful erection that won’t go away
• Long-term damage to the eyes, kidneys, lungs, hips and shoulders, plus gallstones and leg sores

How sickle cell anemia is diagnosed

• Newborn screening. A few drops of blood from the baby’s heel are tested in the first days of life. Every US state does this test.
• Hemoglobin electrophoresis or HPLC. These blood tests sort out the types of hemoglobin in the blood. They confirm sickle cell anemia and tell it apart from sickle cell trait and other forms.
• Quick screening tests. A “sickle solubility” test can show that hemoglobin S is present, but it can’t tell trait from disease. A positive result needs one of the tests above.
• Testing before birth. Parents who both carry the gene can have the pregnancy tested with chorionic villus sampling or amniocentesis. A genetic counselor can explain the options.

Adults who don’t know whether they carry the gene can ask their doctor for a hemoglobin test.

How sickle cell anemia is treated

• Infection protection. Young children take daily penicillin until about age 5 and get extra vaccines, including against pneumonia and meningitis. Yearly flu shots are recommended for everyone with the disease.
• Hydroxyurea. This daily pill helps the body make a type of hemoglobin that resists sickling. It lowers the number of pain crises, chest syndrome episodes and transfusions. It is offered to most children from 9 months of age and to adults.
• Other medicines. L-glutamine powder may reduce pain crises in some people. Folic acid helps the body make new red blood cells.
• Blood transfusions. Used for severe anemia and acute chest syndrome, and given regularly to children at high risk of stroke. Repeated transfusions can build up iron in the body, which is treated with iron-removing medicine.
• Pain care. Mild crises can often be managed at home with fluids, rest, warmth and pain relievers. Severe pain needs hospital care with stronger medicines, often opioids. A written pain plan from your care team helps emergency staff treat you quickly.
• Stem cell transplant. A bone marrow transplant from a matched donor, often a brother or sister, can cure the disease. It carries serious risks and is mostly used for people with severe disease.
• Gene therapy. Since 2023, the FDA has approved two gene therapies for people 12 and older with repeated pain crises. They use the person’s own stem cells, changed in a lab, and require strong chemotherapy first. They are offered only at certain centers.

Living with sickle cell anemia

• Drink plenty of water, especially in hot weather and during exercise.
• Dress warmly in cold weather and avoid swimming in cold water.
• Avoid high altitudes and flights in unpressurized planes.
• Keep up with checkups, yearly eye exams and kidney tests. Children get a yearly ultrasound of the head (transcranial Doppler) to check stroke risk.
• Plan pregnancy with your care team. Pregnancy with sickle cell disease needs close care.

Most children with sickle cell disease in the US now grow into adulthood, and adults are living longer than in the past.

Get emergency care

Call your care team right away or go to an emergency department for:

• A fever of 101°F (38.3°C) or higher
• Chest pain, cough or trouble breathing
• Pain that doesn’t ease with your home pain plan
• A swollen belly, or sudden weakness and very pale skin
• An erection that lasts more than 2 hours
• Sudden vision changes

Call 911 for stroke signs: a drooping face, weakness on one side, trouble speaking or a sudden severe headache.

Common questions about sickle cell anemia

Is sickle cell trait the same as sickle cell anemia?

No. Sickle cell trait means you carry one sickle cell gene. Most people with the trait are healthy and never have pain crises. Rarely, extreme exercise, dehydration or high altitude can cause problems. People with the trait can pass the gene to their children.

Can sickle cell anemia be cured?

Yes, for some people. A stem cell transplant from a matched donor and the newer gene therapies can cure it. Both carry real risks, take months of recovery and are available only at certain centers. Most people manage the disease with daily medicine and regular care.

Is sickle cell anemia only found in Black people?

No. It is most common in people with African ancestry, but anyone can inherit it. Families from Latin America, the Caribbean, the Middle East, India and southern Europe can also carry the gene. Newborn screening tests every baby, whatever their background.

Questions to ask your doctor

• Which type of sickle cell disease do I or my child have?
• Should I take hydroxyurea?
• Am I a candidate for a transplant or gene therapy?
• Can you write me a pain plan for home and the emergency department?
• Should my family members be tested?

Learn more

• Sickle cell disease (National Heart, Lung, and Blood Institute)
• About sickle cell disease (Centers for Disease Control and Prevention)

This guide is general information and doesn’t replace advice from your own doctor. Last updated October 2026.