Sickle cell crisis is a painful episode that may begin suddenly in a person with sickle cell disease and may last for up to a few hours or days. Sickle cell disease affects how hemoglobin—the protein in red blood cells—is able to move oxygen from the lungs to the rest of the body.

People with sickle cell disease have only hemoglobin S, which turns normal, round red blood cells (hemoglobin A) into abnormally curved (sickle) shapes. A sickle cell crisis occurs when these sickle-shaped red blood cells clump together and block small blood vessels that carry blood to certain organs, muscles, and bones. The pain most often occurs in the bones of the spine, arms and legs, the chest, and the abdomen. It may last from hours to days.

Treatment depends on the level of pain and how long it lasts. Sometimes, taking nonprescription pain relievers can help. Other times, a person needs stronger pain relief medicine that is prescribed or given by a doctor.