Cyclophosphamide, also known as cytophosphane or CYC, is a cytotoxic agent medication that suppresses the immune system. Few patients experience serious side effects from cyclophosphamide, but they might suffer from one or more of the milder consequences. Cyclophosphamide side effects can vary, depending on dosage and administration of the drug. Common side effects include a loss of appetite, thinning of the hair, nausea and a skin rash. More seriious cyclophosphamide side effects might include bloody urine, infertility and bladder cancer.
This drug was originally developed as a chemotherapy drug to be used in combination with vincristine to treat small-cell cancers. In smaller doses, cyclophosphamide is used to treat autoimmune diseases, such as vasculitis, multiple sclerosis, Churg-Strauss syndrome, Cogan’s syndrome, lupus and Wegener's granulomatosis. Cyclophosphamide has been found to have side effects in many patients who are given the drug.
Other common cyclophosphamide side effects include: mouth ulcers or thrush, a fungal infection caused by the Candida bacteria; weight loss; diarrhea or stomach pain; missed menstrual periods in females or decreased sperm count in males; and darkening of the skin. Cyclophosphamide might also irritate the bladder and kidneys. To help keep the bladder and kidneys healthy, physicians recommend that patients drink large amounts of fluids while on the drug.
More serious cyclophosphamide side effects might also include: painful urination from bladder inflammation; anemia and fatigue; bruising and bleeding arising from low platelet count; fever, chills, sore throat and shortness of breath. Cyclophosphamide attacks the cells of the immune system, so patients are more susceptible to contagious illnesses and infections. Physicians recommend avoiding crowded areas and people who have contagious illnesses, and they refrain from giving vaccinations to patients who are on cyclophosphamide. To prevent bacterial infection, patients on CYC are often prescribed an antibiotic as a precaution.
Many cyclophosphamide side effects diminish after the patient has ended treatment. The risk of cancer and infertility, however, might continue long after treatment. Long-term cyclophosphamide side effects might include the risk of bladder cancer, leukemia and lymphoma, among other cancers. Risk of cancer is greater for patients who have taken daily oral doses of cyclophosphamide.
Another cyclophosphamide side effect is infertility. Risks appear to be based on length of treatment and cumulative doses. Female patients may experience early menopause and a greater risk of infertility during childbearing years. Both men and women over the age of 30 who are taking cyclophosphamide are more likely to become infertile. Cyclophosphamide might also cause birth defects, so patients are advised to use birth control for at least three months after CYC treatments have ended.