The most common side effects of the most common breast cancer chemotherapy drugs are as follows:Adriamycin (doxorubicin): More common side effects are hair loss, nausea and diarrhea. Bone marrow suppression is also a risk. Less common but more worrisome is a problem with the regulation of a specific heart valve. Anyone receiving this drug will go for cardiac testing (MUGA scan) and be monitored appropriately for the duration. The drug may also cause the urine to be a reddish color.Cytoxan (cyclophosphamide): More common effects include metallic mouth taste, nausea, appetite changes, hair loss, low blood counts, abdominal pain, skin rashes and diarrhea. Irregularities in your menstrual cycle can also occur, and as total dosages increase, fertility declines, and the likelihood of premature menopause increases.5-Fluorouracil: Fairly well tolerated. More common effects are nausea, appetite changes, diarrhea and low blood counts. Rarely, skin darkening or pigment changes can occur.Taxol (paclitaxel): The primary concern is about an allergic reaction, so everyone receiving this drug gets pretreatment with antihistamines and anti-inflammatory drugs. Make sure that someone is in the room with you for at least the first hour of your first Taxol treatment in case you do have an allergic reaction. Common side effects are hair loss, nausea, low blood counts, joint pain and neurological side effects such as weakness, numbness and tingling (which may be temporary during treatment or more permanent, depending on dosage and duration).Taxotere (docetaxel): Like Taxol, there is also a concern for severe allergic reaction, and hair loss will occur. Swelling in the legs and fluid build-up, sometimes in the lungs, can be a problem. More common effects are excessive tearing, fatigue, loss of appetite and severe nausea.Other more general side effects of chemotherapy may include temporary memory loss (often called "chemo brain"), fatigue and depression, all induced by a complex interaction of chemical, physical and emotional factors.