Hi, Welcome to HCM, I have read your query, white blood cells can go down from many conditions and certain medications. The main purpose of WBCs is to fight infection so if they are decreased your body may not be able to fight off infections. Some cause include infections , autoimmune disorders , cancers, overwhelming infections that use up white blood cells faster than they can be produced and drugs that destroy white blood cells. Steroids act on the immune system by blocking the production of substances that trigger allergic and inflammatory actions, such as prostaglandins. However, they also impede the function of white blood cells which destroy foreign bodies and help keep the immune system functioning properly. The interference with white blood cell function yields a side effect of increased susceptibility to infection. The underlying cause for low WBC count needs to be found in order to determine treatment, hence will recommend to contact your clinician to confirm the cause. Thanks