Take this medicine only as directed by your doctor. Do not take more or less of it, and do not take it more often than your doctor ordered. The exact amount of medicine you need has been carefully worked out. Taking too much may increase the chance of side effects, while taking too little may not improve your condition.

Cyclophosphamide is sometimes given together with certain other medicines. If you are using a combination of medicines, make sure that you take each one at the proper time and do not mix them. Ask your health care professional to help you plan a way to remember to take your medicines at the right times.

While you are using cyclophosphamide, it is important that you drink extra fluids so that you will pass more urine. Also, empty your bladder frequently, including at least once during the night. This will help prevent kidney and bladder problems and keep your kidneys working well. Cyclophosphamide passes from the body in the urine. If too much of it appears in the urine or if the urine stays in the bladder too long, it can cause dangerous irritation. Follow your doctor's instructions carefully about how much fluid to drink every day. Some patients may have to drink up to 7 to 12 cups (3 quarts) of fluid a day.

Usually it is best to take cyclophosphamide first thing in the morning, to reduce the risk of bladder problems. However, your doctor may want you to take it with food in smaller doses over the day, to lessen stomach upset or help the medicine work better. Follow your doctor's instructions carefully about when to take cyclophosphamide.

Cyclophosphamide often causes nausea, vomiting, and loss of appetite. However, it is very important that you continue to use the medicine even if you begin to feel ill. Do not stop taking this medicine without first checking with your doctor. Ask your health care professional for ways to lessen these effects.

If you vomit shortly after taking a dose of cyclophosphamide, check with your doctor. You will be told whether to take the dose again or to wait until the next scheduled dose.

Dosing

The dose of cyclophosphamide will be different for different patients. The dose that is used may depend on a number of things, including what the medicine is being used for, the patient's weight, whether the medicine is being given by mouth or by injection, and whether or not other medicines are also being taken. If you are taking or receiving cyclophosphamide at home, follow your doctor's orders or the directions on the label. If you have any questions about the proper dose of cyclophosphamide, ask your doctor.

Missed dose

If you miss a dose of this medicine, do not take the missed dose at all and do not double the next one. Instead, go back to your regular dosing schedule and check with your doctor.

Storage

To store this medicine:

• Keep out of the reach of children.
• Store away from heat and direct light.
• Do not store in the bathroom, near the kitchen sink, or in other damp places. Heat or moisture may cause the medicine to break down.
• Store the oral solution form of this medicine in the refrigerator. Keep it from freezing.
• Do not keep outdated medicine or medicine no longer needed. Be sure that any discarded medicine is out of the reach of children.

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For cyclophosphamide, the following should be considered:

Allergies Tell your doctor if you have ever had any unusual or allergic reaction to cyclophosphamide.

Pregnancy This medicine may cause several different birth defects if either the male or female is taking it at the time of conception or if it is taken during pregnancy. In addition, many cancer medicines may cause sterility. Although sterility occurs commonly with cyclophosphamide, it is usually only temporary.

Be sure that you have discussed this with your doctor before taking this medicine. It is best to use some kind of birth control while you are taking cyclophosphamide. Tell your doctor right away if you think you have become pregnant while taking cyclophosphamide.

Breast-feeding Cyclophosphamide passes into the breast milk. Because this medicine may cause serious side effects, breast-feeding is generally not recommended while you are taking it.

Children This medicine has been tested in children and has not been shown to cause different side effects or problems than it does in adults.

Older adults Many medicines have not been studied specifically in older people. Therefore, it may not be known whether they work exactly the same way they do in younger adults. Although there is no specific information comparing use of cyclophosphamide in the elderly with use in other age groups, it is not expected to cause different side effects or problems in older people than it does in younger adults.

Other medicines Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking or receiving cyclophosphamide, it is especially important that your health care professional know if you are taking any of the following:

• Amphotericin B by injection (e.g., Fungizone) or
• Antithyroid agents (medicine for overactive thyroid) or
• Chloramphenicol (e.g., Chloromycetin) or
• Colchicine or
• Flucytosine (e.g., Ancobon) or
• Ganciclovir (e.g., Cytovene) or
• Interferon (e.g., Intron A, Roferon-A) or
• Methotrexate or
• Plicamycin (e.g., Mithracin) or
• Zidovudine (e.g., AZT, Retrovir) or
• If you have ever been treated with radiation or cancer medicines Cyclophosphamide may increase the effects of these medicines or radiation therapy on the blood

• Cocaine Cyclophosphamide may increase the effects and toxicity of this medicine

• Cytarabine Cyclophosphamide may increase the effects of this medicine on the heart and blood

• Azathioprine (e.g., Imuran) or
• Chlorambucil (e.g., Leukeran) or
• Corticosteroids (cortisone-like medicine) or
• Cyclosporine (e.g., Sandimmune) or
• Mercaptopurine (e.g., Purinethol) or
• Muromonab-CD3 (monoclonal antibody) (e.g., Orthoclone OKT3) There may be an increased risk of infection and development of cancer because cyclophosphamide reduces the body's ability to fight them

• Probenecid (e.g., Benemid) or
• Sulfinpyrazone (e.g., Anturane) Cyclophosphamide may increase the amount of uric acid in the blood. Since these medicines are used to lower uric acid levels, they may not work as well in patients taking cyclophosphamide

• Chickenpox (including recent exposure) or
• Herpes zoster (shingles) Risk of severe disease affecting other parts of the body

• Gout (history of) or
• Kidney stones (history of) Cyclophosphamide may increase levels of uric acid in the body, which can cause gout or kidney stones

• Infection Cyclophosphamide can decrease your body's ability to fight infection

• Kidney disease Effects of cyclophosphamide may be increased because of slower removal from the body

• Liver disease The effect of cyclophosphamide may be decreased

• Prior removal of adrenal gland(s) Toxic effects of cyclophosphamide may be increased, dosage adjustment may be necessary

• Tumor cell accumulation Increased risk of tumor cells entering the bone marrow, due to bone marrow depression from high doses of cyclophosphamide