The following side effects may occur in patients with osteoporosis who are treated with injections: 1) Irregular vaginal bleeding and increased incidence of tumors in the breast and uterus may occur. This condition is common in older women who are menopausal and using estrogen replacement therapy. 2. May lead to hypocalcemia, which is common when patients are treated with calcitonin. 3. May lead to gastrointestinal reactions, such as nausea, vomiting and loss of appetite, which are common when patients are treated with bisphosphonates, such as zoledronic acid. 4. It may lead to abnormal liver and kidney function, which exists in many of these drugs.