White blood cells (WBCs) increase in response to various factors, primarily as a part of the body's immune response. When your body detects an infection, injury, or inflammation, it triggers the release of chemical signals that stimulate the production and release of WBCs from the bone marrow into the bloodstream. The increased number of WBCs allows the immune system to combat pathogens, such as bacteria, viruses, fungi, or parasites, and assist in tissue repair. Additionally, certain medications, such as corticosteroids, can also cause an increase in WBC count. However, persistently high WBC counts or fluctuations outside the normal range may indicate an underlying health condition, such as an infection, inflammatory disorder, autoimmune disease, allergic reaction, bone marrow disorder, or even certain types of cancer. To determine the specific cause of an elevated WBC count, further medical evaluation is necessary.