Sickle cell disease (SCD) is a serious, inherited condition affecting the blood and various organs in the body. It affects the red blood cells, causing episodes of sickling, which produce episodes of pain and other symptoms. In between episodes of sickling, people with SCD are normally well. Long-term complications can occur. Certain conditions can trigger sickling, such as cold, infection, dehydration or low oxygen. Good treatment, started early in life, can prevent complications. So, early diagnosis and specialist treatment are advised for SCD. Sickle cell trait is not the same as sickle cell disease. Sickle cell trait means you carry a sickle cell gene, but it does not normally cause illness.