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This page tells you about the chemotherapy drug combination FC and its possible side effects. There is information about


What FC is

FC is the name of a combination of chemotherapy drugs that includes 

  • Fludarabine (Fludara)
  • Cyclophosphamide

The links above take you to more information about the individual side effects of each drug.

FC is a treatment for chronic lymphocytic leukaemia (CLL).


How you have FC

You usually have FC chemotherapy as cycles of treatment. Each cycle of treatment lasts 4 weeks. Depending on your needs, you may have up to 8 cycles, taking 6 to 8 months in total.

You can either have your treatment

  • As tablets – you take one tablet of fludarabine and one of cyclophosphamide once a day
  • As a drip (infusion) into a vein or as slow injections through a small tube (cannula) put into a vein

You have treatment for 3 to 5 days. Then for the rest of that week and for the following 3 weeks you have no treatment. Your next cycle of treatment then starts 4 weeks after the beginning of the first treatment.

If you are taking tablets it is important that you store them in a safe place away from children. It is very important that you take them 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.

The side effects associated with FC are listed below. You can use the underlined links to find out more about each one. For general information, see our side effects of cancer drugs section.


Common side effects

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

  • An 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, a sore throat, pain passing urine, or you may feel cold and shivery. If you have a severe infection this can be life threatening. Contact your treatment centre straight away if you have any of these effects or if your temperature goes above 38°C. You will have regular blood tests to check your blood cell levels
  • 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 or bleeding gums after brushing your teeth. Or you may have lots of tiny red spots or bruises on your arms or legs (known as petechia)
  • Tiredness and weakness (fatigue) during and after treatment affects about 5 out of 10 people (50%) – most people find their energy levels are back to normal within 6 months to a year
  • A raised temperature happens in up to 4 out of 10 people (40%)
  • Feeling or being sick affects about 3 out of every 10 people (30%) but this is usually well controlled with anti sickness medicines
  • Hair loss – most people have complete hair loss but the hair grows back once the treatment ends
  • Diarrhoea occurs in 3 out of 10 people (30%) – drink plenty of fluids and tell your doctor or nurse if diarrhoea becomes severe or continues for more than 3 days
  • Constipation happens in 3 out of 10 people (30%) – your doctor or nurse may give you laxatives to help prevent this. Tell them if you are constipated for more than 3 days
  • Loss of taste or taste changes
  • Fludarabine may cause changes in your immune system that permanently affect the production of blood cells. The changes may include autoimmune haemolytic anaemia, thrombocytopenia and thrombocytopenic purpura
  • Women may stop having periods (amenorrhoea) but this may be temporary
  • Loss of fertility – you may not be able to become pregnant or father a child after this treatment. Talk to your doctor before starting treatment if you think you may want to have a baby in the future. Men may be able to store sperm before starting treatment

Occasional side effects

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

  • Inflammation of the bladder (cystitis) can cause pain and occasionally blood when passing urine. Contact your doctor or nurse straight away if you see blood in your urine. You need to drink 8 to 12 cups of fluid a day while you are having treatment and for 3 days afterwards
  • Your nails may darken or become ridged
  • Your skin may darken
  • Mouth sores and ulcers

Rare side effects

Fewer than 1 in 100 people have these effects.

  • Nerve changes causing numbness and tingling in fingers and toes
  • 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 build up, leading to swelling of the hands or feet

Important points to remember

You may have a few of these effects. They may be mild or more severe. A side effect may get worse through your course of treatment. Or you may have more side effects as the course goes on. This depends on

  • How many times you've had a drug before
  • Your general health
  • How much of the drug you have (the dose)
  • The way you take the drug (tablets or drip)
  • Other drugs you are having

Coping with side effects

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

Other medicines

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

Pregnancy and contraception

These drugs may harm a baby developing in the womb. It is important not to become pregnant or father a child while you are having treatment and for a few months afterwards. Talk to your doctor or nurse about effective contraception before starting treatment.


Do not breastfeed during this treatment because the drug may come through in the breast milk.

Blood transfusions

If you are having, or have had, fludarabine treatment you must always receive specially treated (irradiated) blood if you need a transfusion. This is to prevent a side effect called graft versus host disease. If you need to have a blood transfusion, check with your doctor or nurse that the blood has been irradiated.


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.


Related information


More information about FC drugs

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 www.medicines.org.uk.

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 www.mhra.gov.uk.

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Updated: 31 December 2014