Zoledronic acid (Reclast) is used to prevent or treat osteoporosis (condition in which the bones become thin and weak and break easily) in women who have undergone menopause ('change of life,' end of regular menstrual periods). Zoledronic acid (Reclast) is also used to treat osteoporosis in men, and to prevent or treat osteoporosis in men and women who are taking glucocorticoids (a type of corticosteroid medication that may cause osteoporosis). Zoledronic acid (Reclast) is also used to treat Paget's disease of bone (a condition in which the bones are soft and weak and may be deformed, painful, or easily broken). Zoledronic acid (Zometa) is used to treat high levels of calcium in the blood that may be caused by certain types of cancer. Zoledronic acid (Zometa) is also used along with cancer chemotherapy to treat bone damage caused by multiple myeloma [cancer that begins in the plasma cells (white blood cells that produce substances needed to fight infection)] or by cancer that began in another part of the body but has spread to the bones. Zoledronic acid (Zometa) is not cancer chemotherapy, and it will not slow or stop the spread of cancer. However, it can be used to treat bone disease in patients who have cancer. Zoledronic acid is in a class of medications called bisphosphonates. It works by slowing bone breakdown, increasing bone density (thickness), and decreasing the amount of calcium released from the bones into the blood.