Get our free Cytoxan coupon and be eligible to receive a discount. You can reduce your Cytoxan cost by up to 75% with our free Cytoxan discount card. Bring it to a participating pharmacy near you to save on your prescription medication.Cyclophosphamide is a cancer medication that interferes with the growth and spread of cancer cells in the body. Cyclophosphamide is used to treat several types of cancer. Cyclophosphamide is also used to treat certain cases of nephrotic syndrome (kidney disease) in children. Cyclophosphamide may also be used for purposes not listed in this medication guide.