10. Prescription Medications
Some prescription medications cause white blood cell counts to drop. Antibiotics destroy healthy, normal cells along with the bacterial invaders that cause infections. During and for a few days to weeks after a person has antibiotic therapy to treat an infection, their white blood cell count may be low. After the course of antibiotics ends, the body slowly rebuilds the level of white blood cells. About four to six weeks after ending antibiotic treatment, white blood cell counts should return to a normal level.