Sickle cell disease (SCD) is a genetic condition that affects the shape and function of your red blood cells (RBCs).

RBCs transport oxygen to your body’s organs and tissues using a protein called hemoglobin to capture oxygen. Healthy RBCs are donut-shaped and very flexible, which allows them to move through the tiniest of your blood vessels, called the capillaries.

However, if you have SCD, certain genetic mutations make your RBCs rigid and shaped like the letter “C” or a sickle. This makes it hard for RBCs to capture and carry enough oxygen.

Sickle-shaped RBCs can also get stuck in your blood vessels, unable to reach many parts of your body. This can cause severe pain known as a sickle cell crisis. Sickle cell crises can start suddenly and last several days, sometimes even weeks or months.

Read this article to learn more about sickle cell crises, what can trigger them, and how you can manage or even avoid them.

Scientists don’t completely understand the exact causes of a sickle cell crisis. Most of the time, it happens because of a physical trigger, but it can also occur without a known cause.

Most commonly, any triggers that cause your blood vessels to constrict can result in a sickle cell crisis. These triggers include:

  • physical or psychological stress
  • cold weather
  • pain
  • alcohol
  • tobacco products
  • loss of fluids (dehydration)
  • infection
  • low blood oxygen (hypoxemia), which can result from very strenuous exercise, high altitude, or certain medical conditions

It can be hard to identify which trigger is responsible for each particular crisis. Often, it can be due to a combination of causes.

There are several types of sickle cell crises:

  • Vaso-occlusive crisis (VOC): A VOC is the most common presentation of sickle cell crisis and can cause severe, often debilitating pain. It happens due to a complex interaction among sickle cells, endothelial cells (the lining of your blood vessels), and other cells in your blood.
  • Splenic sequestration crisis: This causes pain and swelling of the spleen. It happens when a lot of blood becomes entrapped in the spleen. Splenic sequestration crises most commonly occur in young children.
  • Aplastic crisis: This happens when your body doesn’t make enough new RBCs to replace the ones already in your blood. Some viral infections, such as parvovirus B19, can cause an aplastic crisis. These crises cause sudden paleness and weakness.
  • Acute chest syndrome: This is the leading cause of hospitalization and death in people with SCD. It causes chest pain, cough, fever, low blood oxygen, and abnormal substances accumulating in the lungs (lung infiltrates). Acute chest syndrome can follow VOCs.
  • Hemolytic crisis: This happens when large numbers of RBCs are destroyed over a short time. It causes a sudden drop in hemoglobin levels (anemia).

There are other, less frequent types of sickle cell crises, most commonly occurring as complications of VOCs.

Keep in mind that you can have more than one type of sickle cell crisis at a time.

The most common symptoms of sickle cell crises are:

These symptoms usually develop over hours or days.

A VOC, which usually precedes other complications, can cause pain in the following body parts:

  • back
  • legs
  • knees
  • arms
  • chest
  • abdomen

Is sickle cell crisis a medical emergency?

You should get treatment for a severe sickle cell crisis right away to avoid life threatening complications.

The Centers for Disease Control and Prevention (CDC) recommends having a plan for getting help immediately, at any hour, in case of a problem.

Keep a printed copy of your medical records, pain management plan, and a list of all your medications to bring with you to the medical facility.

You should call 911, use local emergency services, or go to an urgent care facility right away if you have SCD and any of the following symptoms:

Call a doctor if you experience one of the following:

  • pain anywhere in the body that won’t go away with home treatment
  • any sudden vision issues
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You can’t prevent all sickle cell crises, but you can avoid triggers and therefore minimize them by:

  • drinking plenty of water (at least eight glasses a day) to avoid dehydration
  • dressing warmly in cold weather and carrying an extra layer just in case
  • avoiding mountain climbing or air flights in an unpressurized cabin
  • sticking to light to moderate exercise
  • paying attention to your stress levels
  • washing your hands often to avoid infections
  • being sure to get all recommended vaccinations, including flu and coronavirus shots and boosters
  • taking folic acid supplements to prevent anemia
  • avoiding alcohol and tobacco products

In addition, be sure to follow a doctor’s recommendations, including taking all recommended medications on time.

Not all sickle cell crises warrant a trip to the emergency room. You can start with home management, but it’s important to get immediate medical attention if home treatment doesn’t have the desired effect.

Home management includes:

If home management doesn’t work, a doctor will likely prescribe you stronger medications for pain. In addition, they’ll check for an underlying infection or dehydration that might be triggering the crisis. They may also give you intravenous (IV) fluids. In very severe cases, you may need a blood transfusion.

Certain medications are approved by the Food and Drug Administration (FDA) to reduce the frequency and duration of VOCs:

Read more about the potential cure for SCD.

A sickle cell crisis is a very painful complication of SCD. It has many triggers, most of which cause constriction of your blood vessels, resulting in the clumping of blood cells in the capillaries.

You can treat mild pain at home, but more severe cases require immediate medical attention. You can prevent sickle cell crises by avoiding their triggers.