Generic name: cyclophosphamide (oral/injection) [ SYE-kloe-FOS-fa-mide ]
Brand names: Cytoxan, Neosar, Cytoxan Lyophilized
Dosage forms: intravenous powder for injection (1 g; 2 g; 500 mg), intravenous solution (100 mg/mL; 200 mg/mL), ... show all 4 dosage forms oral capsule (25 mg; 50 mg), oral tablet (25 mg; 50 mg)
Drug class: Alkylating agents

Medically reviewed by Drugs.com on Aug 8, 2025. Written by Cerner Multum.

What is cyclophosphamide?

Cyclophosphamide is used to treat several types of cancer.

Oral cyclophosphamide is also used to treat minimal change nephrotic syndrome (kidney disease) in children who cannot use other treatments or when other treatments have failed.

Cyclophosphamide may also be used for purposes not listed in this medication guide.

Cyclophosphamide side effects

Get emergency medical help if you have signs of an allergic reaction: hives, difficult breathing, swelling of your face, lips, tongue, or throat.

cyclophosphamide can cause serious or fatal side effects, including:

• unusual bruising or bleeding, new signs of infection (fever, weakness, cough, diarrhea, burning when you urinate);

• bone marrow suppression;

• feeling short of breath on exertion;

• chest discomfort, dry cough or hack;

• feeling weak or tired, loss of appetite, rapid weight loss;

• kidney problems--swelling, urinating less, feeling tired or short of breath, blood in urine;

• heart problems--swelling, rapid weight gain, feeling short of breath;

• liver problems--loss of appetite, nausea, vomiting, stomach pain (upper right side), tiredness, itching, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes);

• low blood sodium--headache, confusion, problems with thinking or memory, weakness, feeling unsteady; or

• low blood cell counts--fever, chills, tiredness, blisters or ulcers in your mouth, skin sores, easy bruising, unusual bleeding, pale skin, cold hands and feet, feeling light-headed or short of breath.

Common side effects of cyclophosphamide may include:

• fever, low blood cell counts;

• mouth sores;

• nausea, vomiting, diarrhea;

• hair loss; or

• missed menstrual periods.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Related/similar drugs

Warnings

You should not use cyclophosphamide if you have a bladder obstruction or other urination problems.

You may feel faint while using cyclophosphamide. Call your doctor right away if you have fast or pounding heartbeats, chest pain, shortness of breath, and sudden dizziness.

Before taking this medicine

You should not use cyclophosphamide if you are allergic to cyclophosphamide or similar medicines, or if you have:

• a bladder obstruction.

Tell your doctor if you have or have ever had:

• weak immune system (caused by disease or by using certain medicines);

• an active or chronic infection (including a bladder infection);

• drink alcohol;

• bladder problems;

• lung disease;

• heart disease;

• if you are receiving other cancer treatments or radiation;

• kidney disease (or if you are on dialysis); or

• liver disease.

Using cyclophosphamide may increase your risk of developing other cancers. Ask your doctor about this risk.

You may need to have a negative pregnancy test before starting this treatment.

May harm an unborn baby. Do not use if you are pregnant. Use effective birth control while using cyclophosphamide and for at least 1 year after your last dose. Tell your doctor if you become pregnant.

Men using cyclophosphamide should use condoms during treatment, and for at least 4 months after treatment ends.

Cyclophosphamide may affect fertility in men or women. Pregnancy could be harder to achieve while either parent is using this medicine.

Cyclophosphamide may cause you to stop having menstrual periods. Your periods should return to normal within a few months after you stop using cyclophosphamide. However, older women may have early menopause due to this effect. Talk to your doctor about this risk.

Do not breastfeed while using this medicine, and for at least 1 week after your last dose.

How is should I use cyclophosphamide?

Follow all directions on your prescription label and read all medication guides or instruction sheets. Use the medicine exactly as directed.

Cyclophosphamide oral is taken by mouth. Doses are based on weight. Your dose may change if you gain or lose weight.

Swallow the tablet/capsule whole and do not crush, chew, or break it.

Cyclophosphamide injection is given as an infusion into a vein. A healthcare provider will give you this injection.

Cyclophosphamide should be taken in the morning.

Drink plenty of liquids while you are using cyclophosphamide.

Cyclophosphamide affects your immune system. You may get infections more easily, even serious or fatal infections. Your doctor will need to examine you on a regular basis.

Cyclophosphamide can lower your blood cell counts. Your blood will need to be tested often. Your cancer treatments may be delayed based on the results.

If you need surgery, tell the surgeon ahead of time that you are using cyclophosphamide. You may need to stop using the medicine for a short time.

Ask your doctor or pharmacist how to safely handle this medicine. Cyclophosphamide can be harmful if it gets on your skin. If this occurs, wash thoroughly with soap and water. Your caregiver may need to wear latex gloves when handling this medicine.

Store at room temperature away from moisture and heat.

What happens if I miss a dose?

For cyclophosphamide oral: Take the medicine as soon as you can, but skip the missed dose if it is almost time for your next dose. Do not take two doses at one time.

For cyclophosphamide injection: In a medical setting you are not likely to miss a dose.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Overdose symptoms may include mouth sores, trouble breathing, fast heartbeats, rapid weight gain, stomach pain, or yellowing of your skin or eyes.

What should I avoid while using cyclophosphamide?

cyclophosphamide may cause blurred vision and may impair your reactions. Avoid driving or hazardous activity until you know how this medicine will affect you. Dizziness or drowsiness can cause falls, accidents, or severe injuries.

Avoid being near people who are sick or have infections. Tell your doctor at once if you develop signs of infection.

What other drugs will affect cyclophosphamide?

Many other drugs can be dangerous when used with cyclophosphamide. Tell your doctor if you also use:

• protease inhibitors such as hiv/aids medications;

• chemotherapy or radiation;

• medicine to prevent organ transplant rejection such as cyclosporine;

• if you use a blood thinner (such as warfarin) and you have routine "INR" or prothrombin time tests;

• heart medications; or

• metronidazole, tamoxifen.

Cyclophosphamide can cause a serious heart problem. Your risk may be higher if you also use certain other medicines for infections, asthma, heart problems, high blood pressure, depression, mental illness, cancer, malaria.

Cyclophosphamide can harm your liver, especially if you also use certain medicines for infections, birth control, high cholesterol, seizures, pain, or arthritis (including Advil).

Cyclophosphamide can harm your kidneys, especially if you also use certain medicines for infections, cancer, osteoporosis, organ transplant rejection, high blood pressure, or pain or arthritis (including Advil, Motrin, and Aleve);

This list is not complete and many other drugs may affect cyclophosphamide. This includes prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible drug interactions are listed here.

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Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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