Sickle cell anemia: what is it, symptoms, treatment

Felix Gussone, MD - Contributor Avatar

Reviewed by Felix Gussone, MD, Ro, 

Felix Gussone, MD - Contributor Avatar

Reviewed by Felix Gussone, MD, Ro, 

last updated: Sep 03, 2021

5 min read

To help you function in everyday life, your body needs some fundamental building blocks. Healthy red blood cells play an important role in your health by carrying oxygen from your lungs to your tissues and organs. Sickle cell anemia can interfere with the cells’ ability to transport oxygen effectively and cause other potentially life-threatening complications. 


Improve and support your health from the comfort of home

What is sickle cell anemia?

While normal red blood cells are round and flexible, sickle cell anemia occurs when red blood cells take on an abnormal, sickle, or crescent-like shape. They also become inflexible and sticky, which can lead to other health problems (Mangla, 2021). 

This abnormality occurs because of a genetic mutation of hemoglobin, a protein red blood cells need to carry oxygen through the body effectively. Because sickle cell anemia involves a hemoglobin mutation, it can result in anemia symptoms and other complications (Sedrak, 2021).

Sickle cell disease is a larger group of genetic blood disorders and one of the most common genetic conditions in the U.S—sickle cell anemia is the most common form of sickle cell disease (Mangla, 2021)

Symptoms of sickle cell anemia

Typically, anemia—including sickle cell anemia—causes symptoms such as shortness of breath, weakness, and fatigue (Turner, 2021). But because the abnormal shape of sickle cells can cause them to become trapped in organs or clog blood vessels, sickle cell anemia symptoms may also include (Mangla, 2021): 

  • Pain, known as a vaso-occlusive crisis or sickle cell crisis, that occurs due to blocked blood flow through vessels in the chest, joints, and abdomen

  • Swelling in hands and feet

  • Joint pain

  • Frequent infections

  • Delayed growth or puberty

  • Vision problems

Sometimes people can develop acute anemia due to a sequestration crisis. In this condition, the sickle cells block the blood vessels leaving the liver or spleen, causing an accumulation and backup of blood in these organs (Mangla, 2021). 

In some people, sickle cell anemia can also cause complications, such as (Mangla, 2021):

  • Acute chest syndrome (a life-threatening complication that includes chest pain, respiratory problems, and fever) 

  • Stroke

  • Kidney disease

  • Organ damage, especially common with severe anemia 

  • Death of bone tissue, or osteonecrosis 

Sickle cell anemia may also cause a higher risk of gallstones, pulmonary hypertension, ischemic stroke, priapism (persistent erections), and kidney disease (Mangla, 2021).

Because the disease affects many parts of the body, it can cause different symptoms in different people. In general, it is linked with lower life expectancy (Sedrak, 2021). 

Causes of sickle cell anemia 

Sickle cell disease is caused by a genetic mutation in the amino acids of the protein hemoglobin. Hemoglobin lives in your red blood cells (RBCs) and is responsible for carrying oxygen to your body’s tissues.  

This genetic mutation occurs when an amino acid called glutamic acid is substituted with another one called valine. This mutation results in abnormally shaped and less flexible red blood cells. These “sickled” cells do not travel through your blood vessels as easily as normal RBCs (leading to symptoms and potential complications) (Adebeyi, 2019).

Types of sickle cell disease 

Sickle cell anemia is only one type of sickle cell disease. However, each type results from a separate genetic mutation involving the RBCs. The main forms of sickle cell disease are HbSS, HbSC, and HbS thalassemia.


This is the most common type of sickle cell disease and is the one referred to as sickle cell anemia. People with this type of sickle cell disease inherit two sickle cell genes (one from each parent), also called a homozygous mutation—it is also the most severe form of sickle cell disease (Mangla, 2021).


People with HbSC inherit a sickle cell gene from one parent and an abnormal hemoglobin gene (“C”) from another parent—a heterozygous mutation. This is the second most common type of sickle cell disease and is a milder form, sometimes without symptoms (Mangla, 2021). 

HbS beta thalassemia

This type of sickle cell disease occurs when someone inherits a sickle cell gene from one parent and a gene for another type of anemia called beta thalassemia from another parent (Bajwa, 2021).

Risk factors for sickle cell anemia 

Sickle cell anemia is a genetic blood disorder, so it happens in people who are born with a genetic mutation that causes sickled cells. Because it’s so common, all newborns are tested for the disease shortly after birth (Mangla, 2021).

Some groups of people have an increased risk for the disease. For example, African Americans are more likely to have sickle cell anemia (Mangla, 2021). In sub-Saharan Africa, up to one-third of adults carry one gene for sickle cell anemia—known as sickle cell trait. It is so common in this area because sickle cell trait protects against mosquito-borne malaria (Mangla 2021). 

People of Hispanic origin are also more likely to have sickle cell anemia (Mangla, 2021).

It’s important to note that not everyone with sickle cell trait has anemia. People with the trait can live normal lives, but they may pass the disease on to their children if their partner also has a genetic mutation (Mangla, 2021).

Diagnosis of sickle cell anemia 

In the U.S., most people with sickle cell anemia are diagnosed during prenatal or newborn screenings by blood tests that measure the amount of hemoglobin in the blood and look for potential blood disorders (Sedrak, 2021). 

If you have symptoms of sickle cell anemia, your healthcare provider will likely run a complete blood count (CBC) with various tests and measurements on your red blood cells (Sedrak, 2021). But a CBC and the presence of symptoms aren’t enough to make a diagnosis. To make a formal diagnosis, healthcare providers need to test the actual red blood cells to confirm the sickling. 

One way to do that is in a lab procedure called hemoglobin electrophoresis, in which an electric current is applied to a blood sample to separate normal and abnormal hemoglobin (Mangla, 2021).

If other symptoms are present, such as those of acute chest syndrome, a healthcare provider may conduct imaging, including an x-ray (Sedrak, 2021).

Sickle cell anemia treatment 

Several treatments focus on preventing sickle hemoglobin production or reducing the amount of sickle hemoglobin in the body. Examples include hydroxyurea, crizanlizumab, and voxelotor (Mangla, 2021).

In 2017, the FDA approved L-glutamine oral powder to prevent complications of sickle cell disease. Scientists don’t know exactly how this works, but they think it may reduce oxidative stress (Neumayr, 2019). Clinical trials show that it can reduce the number of sickle cell crises, with or without other medical treatments (Niihara, 2018).

Bone marrow transplants are the only potential cure (Mangla, 2021). But unfortunately, fewer than 25% of people with sickle cell have a suitable stem cell donor (Meier, 2018). 

Sickle cell anemia treatment also involves preventative care. If a person is diagnosed with sickle cell anemia, healthcare providers routinely monitor them for risk factors and early signs of complications (Sedrak, 2021). Routine vaccinations can also help prevent infections and associated complications (Mangla, 2021).

If a complication from sickle cell disease arises, the provider will manage them accordingly. The treatment ultimately depends on the complication. 

For example, acute chest syndrome may require antibiotics, oxygen treatment, and blood transfusions (Mangla, 2021). During pain crises—when the abnormally shaped red blood cells interfere with blood flow in an organ—a healthcare provider may suggest NSAIDs or prescription painkillers, including opioids. If that patient has a fever, the provider may check for an infection and treat it (Sedrak, 2021).

Prevention of sickle cell anemia 

Because sickle cell anemia involves a genetic mutation, it’s not possible to prevent it. However, with routine medical care, healthcare providers can help to prevent complications (Sedrak, 2021). As medication and treatment options increase, survival rates and quality of life will, too. 


If you have any medical questions or concerns, please talk to your healthcare provider. The articles on Health Guide are underpinned by peer-reviewed research and information drawn from medical societies and governmental agencies. However, they are not a substitute for professional medical advice, diagnosis, or treatment.

  • Adebiyi, M. G., Manalo, J. M., Xia, Y. (2019). Metabolomic and molecular insights into sickle cell disease and innovative therapies. Blood Advances . 23;3 (8):1347-1355. doi: 10.1182/bloodadvances.2018030619. Retrieved from:

  • Adesina, O. O., & Neumayr, L. D. (2019). Osteonecrosis in sickle cell disease: an update on risk factors, diagnosis, and management. Hematology. American Society of Hematology. Education Program , 2019 (1), 351–358. doi: 10.1182/hematology.2019000038. Retrieved from

  • Azar, S., & Wong, T. E. (2017). Sickle Cell Disease: A Brief Update. The Medical Clinics of North America , 101 (2), 375–393. doi: 10.1016/j.mcna.2016.09.009. Retrieved from

  • Bajwa, H., & Basit, H. (2021). Thalassemia. [Updated Aug. 11, 2021]. In: StatPearls [Internet] . Retrieved from

  • Bender, M.A. (2003). Sickle Cell Disease. Gene Reviews. Retrieved from:

  • Kato, G. J., Piel, F. B., Reid, C. D., Gaston, M. H., Ohene-Frempong, K., Krishnamurti, L., et al. (2018). Sickle cell disease. Nature reviews. Disease primers , 4 , 18010. doi: 10.1038/nrdp.2018.10. Retrieved from

  • Mangla, A., Ehsan, M., Agarwal, N., et al. (2021). Sickle cell anemia. [Updated April 14, 2021]. In: StatPearls [Internet]. Retrieved from

  • Meier, E. R. (2018). Treatment Options for Sickle Cell Disease. Pediatric Clinics of North America , 65 (3), 427–443. doi: 10.1016/j.pcl.2018.01.005. Retrieved from

  • Meremikwu, M. M., & Okomo, U. (2016). Sickle cell disease. BMJ Clinical Evidence . Retrieved from

  • Neumayr, L. D., Hoppe, C. C., & Brown, C. (2019). Sickle cell disease: current treatment and emerging therapies. The American Journal of Managed Care , 25 (18 Suppl), S335–S343. Retrieved from

  • Niihara, Y., Miller, S. T., Kanter, J., Lanzkron, S., Smith, W. R., Hsu, L. L., et al & Investigators of the Phase 3 Trial of l-Glutamine in Sickle Cell Disease (2018). A phase 3 trial of l-glutamine in sickle cell disease. The New England Journal of Medicine , 379(3), 226–235. doi:10.1056/NEJMoa1715971. Retrieved from

  • Sedrak, A. & Kondamudi, N. P. (2021). Sickle cell disease. [Updated Jul. 21, 2021]. In: StatPearls [Internet]. Retrieved from

  • Turner, J., Parsi, M., Badireddy, M. (2021). Anemia. [Updated Aug. 11, 2021]. In: StatPearls [Internet] . Retrieved from

  • Ware, R. E., de Montalembert, M., Tshilolo, L., & Abboud, M. R. (2017). Sickle cell disease. Lancet (London, England) , 390 (10091), 311–323. doi: 10.1016/S0140-6736(17)30193-9. Retrieved from

How we reviewed this article

Every article on Health Guide goes through rigorous fact-checking by our team of medical reviewers. Our reviewers are trained medical professionals who ensure each article contains the most up-to-date information, and that medical details have been correctly interpreted by the writer.

Current version

September 03, 2021

Written by

Ashley Braun, RD, MPH

Fact checked by

Felix Gussone, MD

About the medical reviewer

Felix Gussone is a physician, health journalist and a Manager, Medical Content & Education at Ro.