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What cyclophosphamide is

Cyclophosphamide is a chemotherapy drug used to treat some types of cancer, including breast cancer, lung cancer, myeloma and some lymphomas and leukaemias.


How cyclophosphamide works

Cyclophosphamide works by sticking to one of the cancer cell's DNA strands so the cell can't divide into 2 new cells. DNA is the genetic code in the nucleus of all animal and plant cells. It controls everything the cell does.


How you have cyclophosphamide

You usually have cyclophosphamide as an injection into a vein (intravenously). You can have it through a thin, short tube (a cannula) put into a vein in your arm each time you have treatment. Or you may have them through a central line, a portacath or a PICC line. These are long, plastic tubes that give the drugs directly into a large vein in your chest. You have the tube put in just before your course of treatment starts and it stays in place as long as you need it.

Cyclophosphamide also comes as tablets that you swallow, ideally on an empty stomach. It is very important that you take tablets according to the instructions your doctor or pharmacist gives you. For example, whether you have a full or empty stomach can affect how much of a drug gets into your bloodstream. You should take the right dose, not more or less. And never stop taking a cancer drug without talking to your specialist first.

You usually have chemotherapy as a course of several cycles of treatment. The treatment plan for cyclophosphamide depends on which type of cancer you have. There is information about planning chemotherapy in the main chemotherapy section.

The side effects associated with cyclophosphamide are listed below. You can use the links (underlined) to find out more about each side effect. Where there is no link, look in our cancer drugs side effects section or use the search box at the top of the page.


Common side effects

More than 10 in every 100 people have one or more of the side effects listed below.

A temporary drop in the number of blood cells made by the bone marrow, causing

  • Increased risk of getting an infection from a drop in white blood cells – it is harder to fight infections and you can become very ill. You may have headaches, aching muscles, a cough, sore throat, pain passing urine or feel cold and shivery
  • Tiredness and breathlessness due to a drop in red blood cells (anaemia) – you may need a blood transfusion
  • Bruising more easily due to a drop in platelets – you may have nosebleeds, bleeding gums after brushing your teeth, or lots of tiny red spots or bruises on your arms or legs (known as petechia)

Some of these side effects can be life threatening, particularly infections. You should contact your treatment centre if you have any of these effects. Your doctor will check your blood counts regularly to see how well your bone marrow is working.

Other common side effects include

  • Tiredness (fatigue) during and after treatment – most people find their energy levels are back to normal within 6 months to a year
  • Nausea and vomiting – this is usually mild
  • Loss of appetite
  • Hair loss or hair thinning usually starts about 3 to 4 weeks after your first dose – a cold cap may help to stop you losing your hair, but you need to talk to your doctor about how advisable this is with your type of cancer
  • Women may stop having periods (amenorrhoea) but this may only be temporary
  • Loss of fertility – you may not be able to get pregnant or father a child after treatment with this drug. It is important to talk to your doctor about fertility before starting treatment.
  • Cyclophosphamide may have a harmful effect on a developing baby – do talk to your doctor or nurse about contraception before having treatment if there is any chance that you or your partner could become pregnant

Occasional side effects

Between 1 and 10 in every 100 people have one or more of these.

  • Diarrhoea – you should drink plenty of fluids. If your diarrhoea is severe or continues you could become dehydrated so let your doctor or nurse know
  • Your nails may darken or become ridged
  • Your skin may darken
  • Mouth ulcers
  • Inflammation of the bladder (cystitis) can cause pain and occasionally blood when passing urine. If you see blood in your urine contact your doctor straight away. You should drink 8 to 12 cups of fluid a day. If you are having cyclophosphamide through a drip you will have extra fluids through the drip too

Rare side effects

Fewer than 1 in 100 people have these.

  • There is a small risk that you may get a second cancer some years after cyclophosphamide treatment
  • Damage to heart muscle which is usually temporary but for a small number of people may be permanent – your doctor will check your heart before and after your treatment
  • Changes in lung tissue may lead to a cough or breathlessness
  • Fluid retention leading to swollen hands or ankles

Important points to remember

The side effects above may be mild or more severe. A side effect may get better or worse through your course of treatment, or more side effects may develop as the course goes on. This depends on

  • How many times you've had the drug before
  • Your general health
  • The amount of the drug you have (the dose)
  • Other drugs you are having

Talk to your doctor, pharmacist or nurse about all your side effects so that they can help you manage them. Your nurse will give you a contact number you can ring if you have any questions or problems. They can give you advice or reassure you. If in doubt, call them.

Tell your doctor about any other medicines you are taking, including vitamins, herbal supplements and over the counter remedies – some drugs can react together.


Immunisations and chemotherapy

You should not have immunisations with live vaccines while you are having chemotherapy or for at least 6 months afterwards. In the UK, these include rubella, mumps, measles (usually given together as MMR), BCG, yellow fever and Zostavax (shingles vaccine).

You can have other vaccines, but they may not give you as much protection as usual until your immune system has fully recovered from your chemotherapy. It is safe to have the flu vaccine.

It is safe for you to be in contact with other people who've had live vaccines as injections. There can be problems with vaccines you take by mouth (oral vaccines), but not many people in the UK have these now. So there is usually no problem in being with any baby or child who has recently had any vaccination in the UK. You might need to make sure that you aren't in contact with anyone who has had oral polio, cholera or typhoid vaccination recently, particularly if you live abroad.


More information about cyclophosphamide

This page does not list all the very rare side effects of this treatment that are very unlikely to affect you. For further information look at the Electronic Medicines Compendium website at

If you have a side effect not mentioned here that you think may be due to this treatment you can report it to the Medicines Health and Regulatory Authority (MHRA) at

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Updated: 28 August 2012