Sickle cell anemia is a blood disorder where red blood cells become crescent-shaped instead of round, which causes them to get stuck in blood vessels and break down faster than your body can replace them

In sickle cell anemia, a genetic mutation changes how your body makes hemoglobin—the protein inside red blood cells that carries oxygen. Instead of staying flexible and disc-shaped, the hemoglobin molecules stick together when oxygen levels drop, forcing the entire cell into a rigid crescent or sickle shape. These stiff cells jam in small blood vessels, blocking blood flow and oxygen delivery to tissues. They also die much sooner than normal red blood cells (10 to 20 days instead of 120 days), which means your body cannot make new ones fast enough to keep up.

The result is chronic anemia—not enough healthy red blood cells—plus pain, organ damage, and other complications that can be serious. Sickle cell anemia is inherited: you get it only if both parents pass you the sickle cell gene. If you inherit the gene from only one parent, you have sickle cell trait, which usually causes no symptoms but can be triggered under extreme physical stress.

Key Takeaways

  • Sickle cell anemia happens when a genetic mutation makes red blood cells become crescent-shaped, causing them to block blood vessels and die faster than normal.
  • You are born with sickle cell anemia only if both your parents carry and pass you the sickle cell gene.
  • The main complications are pain crises (sudden severe pain), organ damage, stroke, and chronic anemia that makes you tired and short of breath.
  • Newborn screening catches sickle cell anemia early, and treatments like hydroxyurea, blood transfusions, and bone marrow transplants can reduce symptoms and extend life.
  • People with sickle cell anemia need regular medical care, including preventive antibiotics and monitoring for organ damage.

How the sickle cell gene is inherited

Sickle cell anemia follows an autosomal recessive inheritance pattern. That means you need two copies of the sickle cell gene—one from each parent—to have the disease. If both parents carry the gene, there is a 25 percent chance with each pregnancy that the child will have sickle cell anemia, a 50 percent chance the child will have sickle cell trait, and a 25 percent chance the child will inherit neither.

Sickle cell anemia is most common in people whose ancestors came from Africa, the Mediterranean, the Middle East, and parts of South Asia. In the United States, about 1 in 13 Black newborns and 1 in 36 Hispanic newborns have sickle cell trait; fewer have the full disease. Genetic counseling can help families understand their risk if they know the disease runs in their family.

What happens during a pain crisis

A pain crisis (also called a vaso-occlusive crisis) is the hallmark symptom of sickle cell anemia. It happens when sickled cells block blood vessels, cutting off oxygen to tissues. The pain can be sudden and severe—in the bones, joints, chest, or abdomen—and can last hours to days. Some people have a few crises a year; others have many more. Triggers include cold exposure, dehydration, infection, stress, and physical exertion, though sometimes no trigger is obvious.

During a crisis, the person needs strong pain medication, fluids, and oxygen. Most crises are managed in an emergency room or hospital. Between crises, pain may be mild or absent, which can make the disease invisible to people around the person—but the damage is still happening inside.

Organ damage and other serious complications

Over time, repeated blockages and low oxygen damage organs. The lungs can develop acute chest syndrome (sudden chest pain, fever, and breathing trouble) or chronic lung disease. The kidneys can fail. The liver can be damaged. Bones can develop necrosis (death of bone tissue), especially in the hip and shoulder. The eyes can lose vision. The spleen, which filters blood, often stops working by adulthood, raising infection risk.

Stroke is a major risk in children with sickle cell anemia because blocked vessels in the brain can cut off blood supply. About 10 percent of children with sickle cell anemia have a stroke by age 20 without preventive treatment. Gallstones are also common because the rapid breakdown of red blood cells produces excess bilirubin. Many people with sickle cell anemia develop chronic pain that persists even between crises.

How sickle cell anemia is diagnosed and monitored

Most cases are caught through newborn screening, which tests blood spots from all newborns in the United States. A positive newborn screen means the baby has sickle cell anemia or sickle cell trait; follow-up testing confirms which one. If someone is not screened at birth, a blood test called hemoglobin electrophoresis can diagnose the disease at any age by showing what types of hemoglobin are present.

Once diagnosed, monitoring includes regular blood counts to track anemia severity, imaging to check for organ damage, and screening for complications like stroke risk and lung disease. A primary care doctor and a hematologist (blood specialist) usually work together. Some people also see specialists for pain management, cardiology, nephrology, or other organ-specific care depending on what damage has developed.

Treatments that reduce symptoms and complications

Hydroxyurea is the most common medication for sickle cell anemia. It increases fetal hemoglobin (a type of hemoglobin that does not sickle), which reduces the number of crises and organ damage. It also lowers the need for blood transfusions. Hydroxyurea does not cure the disease, but it significantly improves quality of life for many people.

Blood transfusions replace sickled cells with healthy ones. They are used during crises, before surgery, or regularly to prevent stroke in high-risk children. Chronic transfusions carry risks—iron buildup in organs and sensitization to blood antigens—so they are used only when the benefit outweighs the risk.

Bone marrow transplant (also called hematopoietic stem cell transplant) is the only cure for sickle cell anemia. It works best in children with a matched sibling donor and has the highest success rates when done early. For adults or those without a matched donor, the risks are higher. Newer gene therapy approaches are being studied and may offer another path to cure in the future.

Preventive care includes antibiotics (especially penicillin) to prevent bacterial infections, folic acid to support red blood cell production, pain management plans, and vaccinations. Staying hydrated, avoiding extreme cold, and managing stress help reduce crisis frequency.

Living with sickle cell anemia: school, work, and daily life

People with sickle cell anemia can work, go to school, and live full lives, but the disease requires ongoing management. Frequent pain crises and hospitalizations can interrupt school or work. Fatigue from chronic anemia is real and affects daily activities. Some people need workplace accommodations like flexible scheduling, access to water and bathrooms, or the ability to take breaks when pain starts.

Disclosure to employers and schools is a personal choice, but it can help secure accommodations under the Americans with Disabilities Act (ADA). Many people benefit from connecting with sickle cell support groups, both for practical information and emotional support. Mental health care is important too, since chronic pain and the unpredictability of crises take a psychological toll.

Frequently Asked Questions

Can you catch sickle cell anemia from someone else?

No. Sickle cell anemia is genetic and inherited only from parents. You cannot catch it through contact, blood exposure, or any other means. Only people born with the gene mutation have the disease.

What is the difference between sickle cell anemia and sickle cell trait?

Sickle cell trait means you carry one copy of the sickle cell gene but have two normal hemoglobin genes. Most people with trait have no symptoms and live normal lifespans. Sickle cell anemia means you have two copies of the sickle cell gene and experience the symptoms and complications described in this article.

How long do people with sickle cell anemia live?

Life expectancy has improved significantly with modern treatment. Many people now live into their 50s or beyond, though some die younger from complications like stroke or organ failure. Hydroxyurea and other treatments have extended lifespans, and outcomes continue to improve.

Can sickle cell anemia be cured?

Bone marrow transplant can cure sickle cell anemia, but it works best in children with a matched sibling donor and carries significant risks. Gene therapy is being studied as another potential cure. For most people, treatment focuses on managing symptoms and preventing complications rather than curing the disease.

What should someone with sickle cell anemia avoid?

Avoid dehydration, extreme cold, high altitudes, intense physical exertion without gradual training, and situations that cause extreme stress. Infections, smoking, and alcohol can also trigger or worsen crises. A hematologist can give specific guidance based on the individual's disease severity.