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Busulfan (Myleran, Busilvex)

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This page tells you about the chemotherapy drug busulfan and its possible side effects. There are sections about


What busulfan is

Busulfan is a chemotherapy drug most often given as low dose treatment for a long time to treat chronic myeloid leukaemia. Or you may have it in higher doses before a bone marrow or stem cell transplant for other types of cancer and leukaemia. Busulfan tablets are called Myleran and the injections are called Busilvex. Busulfan is an alkylating agent, which works by sticking to one of the cancer cell's DNA strands. The cell cannot then divide into 2 new cells.


How you have busulfan

Busulfan comes in 2mg white tablets, 25mg capsules and as a clear liquid given by injection into a vein.

It is very important that you take tablets according to the instructions your doctor or pharmacist gave you. Whether you have a full or empty stomach, for example, 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.

Doctors usually give chemotherapy as a course of several cycles of treatment. The treatment plan for busulfan depends on which cancer you have. There is detailed information about chemotherapy treatment planning in our planning chemotherapy section.

We've listed the side effects associated with busulfan below. You can click on the links to find out more about each side effect. Where there is no link please see our cancer drug 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

  • Fatigue (tiredness) during and after treatment – most people find their energy levels are back to normal within 6 months to a year
  • Feeling or being sick is rare with low dose treatment, but common with higher doses (especially before a bone marrow or stem cell transplant) – taking busulfan tablets on an empty stomach may help
  • Loss of appetite is rare with low dose treatment, but common with higher doses
  • Busulfan may have a harmful effect on a developing baby – it is not advisable to get pregnant or father a child while taking this drug, so talk about contraception with your doctor before having treatment if there is any chance that you or your partner could become pregnant
  • Women may stop having periods (amenorrhoea) but this may only be temporary
  • Loss of fertility may happen with this drug – you may not be able to get pregnant or father a child after treatment so it is important to talk to your doctor about your fertility before starting treatment

Occasional side effects

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

  • Hair loss – this is rare with low doses but can happen with high dose treatment
  • A sore mouth is rare with low dose treatment, but can be severe with high doses – do tell your doctor or nurse as you can take painkillers and use mouthwashes to help
  • Skin changes – you may get an itchy rash or your skin may darken in places, particularly your hands and nail beds
  • Diarrhoea is rare with low doses, but can happen with high dose treatment – drink plenty of fluids and tell your doctor or nurse if diarrhoea becomes severe, or continues for more than 3 days

Rare side effects

Fewer than 1 in 100 people have these effects.

  • Lung problems – you may have a cough or wheezing, which can happen straight away or up to 10 years after your treatment
  • Fits (seizures) with high dose treatment – your doctor will give you tablets to prevent this
  • Liver changes – you will have blood tests to check for this
  • Difficulty sleeping, dizziness, or depression can happen with high dose treatment – tell your doctor or nurse about this
  • There is a small risk of developing another cancer in the future after treatment with busulfan
  • Soreness, tenderness and swelling of the breasts
  • There is a small risk of developing cataracts of the eye, causing blurred or cloudy vision

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 chemotherapy nurse, clinic or ward 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.

Tell your doctor about any other medicines you are taking, including vitamins, herbal supplements and other 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 busulfan

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: 24 August 2012