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Cytoxan (cyclophosphamide)

What is Cytoxan?

Cytoxan, approved by the FDA in November 1959, is the brand name for cyclophosphamide which is one of the drugs in the group called antineoplastics and the sub-group of antineoplastics called alkylating agents.  Cytaxan is a medication used as chemotherapy and to suppress the immune system.Cyclophosphamide treats a range of cancers including:

  • Leukemia
  • Lymphoma
  • Hodgkin’s disease
  • Small cell lung cancer
  • Multiple myeloma
  • Neuroblastoma
  • Retinoblastoma
  • Soft tissue cancers

How does it work?

The liver converts cyclophosphamide into the chemicals acrolein and phosphoramide. These active compounds hinder genetic material DNA to prevent cancer cells from growing and reproducing. Unfortunately, cyclophosphamide also affects normal cells and can result in significant side effects, and suppresses the immune system.



  • The 500 mg vial contains 534.5 mg cyclophosphamide monohydrate.
  • The 1 g vial contains 1069.0 mg cyclophosphamide monohydrate.
  • The 2 g vial contains 2138.0 mg cyclophosphamide monohydrate.


The cyclophosphamide tablets are to be taken orally and contain either 25 mg or 50 mg of cyclophosphamide. forms. The inactive ingredients include:

  • Acacia
  • FD&C Blue No. 1
  • D&C Yellow No. 10
  • Aluminum Lake
  • Lactose
  • Magnesium stearate
  • Starch
  • Stearic acid
  • Talc


Your dose of cyclophosphamide will depend according to your condition, other medications you’re taking, body weight, and whether you have been prescribed Cytoxan as an injection or a tablet.


In its intravenous form, Cytoxan is injected into the skin on a prepared area as often as twice a week, however, larger doses are administered once every 3 to 4 weeks. Injections are supervised by a medical professional as the injection needs to be handled very carefully with sterile equipment.


Tablets are taken daily at smaller doses. Larger doses are taken with intervals of 2 to 4 weeks between doses. To reduce the possibility of bladder issues you should take your tablets in the morning with food. It would be helpful to discuss with your doctor the best dosing schedule for you.

Despite the side effects, it is vital that you continue using Cytoxan and do not suddenly stop taking it before discussing it with your doctor. If you vomit soon after taking the medication, you should contact your doctor for instructions. You may need to take another dose or skip it.


Overdose symptoms can include:

  • mouth sores
  • breathing difficulties
  • rapid heartbeats
  • rapid weight gain
  • stomach pain
  • yellowing skin or eyes

If you believe you or someone else has overdosed on Cytoxan, you should contact your doctor as soon as possible. If someone has collapsed or is no longer breathing after using Cytoxan, call the emergency services.

Side Effects

If you are concerned about experiencing side effects from taking this medication, you should talk it over with your doctor and weigh up the risks against the benefits. Many of these side effects may disappear over time or can be managed. Your pharmacist should be able to make recommendations for managing these side effects, however, you should contact your doctor if they become severe or significantly uncomfortable.

The side effects of this medication are not experienced by everyone who takes it, but at least 1% of people taking this medication have experienced those listed below.

  • diarrhea
  • fatigue
  • feeling generally unwell
  • headache
  • loss of appetite
  • nausea
  • temporary hair loss
  • vomiting

Serious side effects

These serious side effects are rare but can cause serious issues if they are not addressed. If you experience any of these, you should see your doctor as soon as possible.

  • blood in the urine
  • burning or pain with urination
  • confusion
  • dizziness
  • fever or chills with cough or hoarseness
  • prickling, tingling, or numb arms or legs
  • redness, swelling, or pain at the site of injection
  • signs of anemia:
    • dizziness
    • pale skin
    • unusual tiredness or weakness
    • shortness of breath
  • signs of heart failure:
    • shortness of breath
    • fatigue
    • swelling in legs, ankles, feet
  • signs of infection:
    • fever or chills
    • severe diarrhea
    • shortness of breath
    • prolonged dizziness
    • headache
    • stiff neck
    • weight loss
    • listlessness
  • signs of kidney problems:
    • increased nighttime urination
    • decreased urine production
    • blood in the urine
    • change of urine color
  • signs of liver problems;
    • nausea
    • vomiting
    • diarrhea
    • loss of appetite
    • weight loss
    • yellowing of the skin or eyes
    • dark urine, pale stools
  • signs of lung inflammation:
    • darkening of the lips or fingernails
    • persistent cough
    • burning sensation in the chest
  • skin inflammation
  • mouth and lip sores
  • symptoms of low blood pressure:
    • fainting
    • dizziness
    • lightheadedness
    • blurred vision
    • increased thirst
    • nausea
  • vein inflammation

Side effects requiring urgent medical attention

If you experience any of the following side effects, discontinue the treatment and immediately seek the attention of a medical professional.

  • seizures
  • signs of an allergic reaction:
    • swollen mouth or tongue
    • breathing difficulties

Side effects other than those listed above are possible. If any symptoms develop that worry you whilst taking this medication, you should discuss them with your doctor.

Warnings and Precautions

Always check the ingredients of any medication you take for anything you may be allergic to. You should not take this medication if you are allergic to it or any of its ingredients.

Make sure your doctor is aware of any medical conditions or allergies you have as this may impact whether or not they recommend this medication for you.

You should not take this medication if you:

  • are allergic to cyclophosphamide or any of this medication’s ingredients
  • are breast-feeding
  • have inflammation of the bladder or urinary outflow obstructions
  • have severe liver problems
  • have severe kidney problems
  • have a low platelet count
  • have a very low white blood cell count
  • have an active infection, particularly varicella-zoster infection

Your bladder may become irritated if urine containing cyclophosphamide remains in it for too long. That means it is vital that you drink fluids while taking the medication so that it may pass in urine and not remain in the bladder for too long. This process may necessitate 7 to 12 cups of fluid each day.


Cytoxan can cause a low red blood cell count (anemia), contact your doctor as soon as you can if you notice symptoms such as:

  • breathlessness
  • feeling abnormally tired
  • pale skin


Cytoxan can make it difficult for cuts to stop bleeding since it causes a drop in the number of platelets in the blood. Inform your doctor as soon as you can if you notice any of the symptoms, such as:

  • frequent nosebleeds
  • unexplained bruising
  • black and tarry stools


If you have heart problems, you should discuss with your doctor how this medication may impact them as inflammation of the heart and irregular heartbeats have been reported after using Cytoxan. Immediately inform your doctor if you notice any of the following:

shortness of breath

  • chest pain
  • rapid heartbeat
  • swollen ankles
  • rapid weight gain


Side effects can occur if the kidneys fail to adequately remove this medication from your body. Kidney disease or reduced kidney function can impact the kidney’s ability to do this. If you have these issues, you should discuss with your doctor how Cytoxan may affect your condition, how effective the medication will be, and whether you may require any special monitoring.


You should make doctors performing surgery on you aware if you have taken Cytoxan within the last 10 days prior to your surgery.

Drug interactions

This medication may interact with any of the following drugs, so if you are taking any of them you should let your doctor know or seek guidance from your pharmacist.

  • allopurinol
  • amiodarone
  • amphotericin B
  • azathioprine
  • bacillus Calmette-Guérin (BCG)
  • belimumab
  • carbamazepine
  • ciprofloxacin
  • clozapine
  • colchicine
  • cyclosporine
  • dabrafenib
  • deferiprone
  • denosumab
  • digoxin
  • echinacea
  • efavirenz
  • etanercept
  • filgrastim
  • fingolimod
  • grapefruit juice
  • HIV protease inhibitors, such as:
    • atazanavir
    • indinavir
    • ritonavir
    • saquinavir
  • indomethacin
  • leflunomide
  • lumacaftor
  • mifepristone
  • natalizumab
  • nevirapine
  • nilotinib
  • nivolumab
  • other cancer medications, such as:
    • busulfan
    • dauronrubicin
    • doxorubicin
    • idarubicin
  • phenobarbital
  • phenytoin
  • pimecrolimus
  • rifampin
  • roflumilast
  • tacrolimus
  • thiazide diuretics (water pills), such as:
    • hydrochlorothiazide
    • indapamide
    • metolazone
  • tofacitinib
  • vaccines
  • warfarin

Frequently Asked Questions

You should prime your inhaler if using it for the first time, if you dropped it, or if you haven’t used it for more than 7 days.