Busulfan is a type of chemotherapy drug. You pronounce it as byoo-sul-fan. It is a treatment for polycythaemia vera, essential thrombocythaemia and myelofibrosis. They are all part of a group of conditions called myeloproliferative neoplasms or myeloproliferative disorders.

What is busulfan?

Busulfan is a chemotherapy drug. You might have it as a treatment for:

  • chronic myeloid leukaemia (CML) 
  • other types of cancer that need treatment with a stem cell or bone marrow transplant
  • certain types of blood disorders called myelodysplastic syndromes (MDS)

You might have busulfan on its own or with other cancer drugs.

How does busulfan work?

Busulfan is a type of chemotherapy drug called an alkylating agent. It works by interfering with the DNA Open a glossary item in cancer cells. The busulfan sticks to one of the DNA strands of the cancer cell. The cells then can’t divide into 2 new cells, so the cancer can’t grow. 

How do you have busulfan?

You have busulfan as tablets or you might have it as a drip into your bloodstream (intravenously).

Taking your tablets

You must take tablets according to the instructions your doctor or pharmacist gives you.

You should take the right dose, not more or less.

Talk to your healthcare team before you stop taking a cancer drug, or if you miss a dose.

Into your bloodstream

You might have treatment through a long plastic tube that goes into a large vein in your chest. The tube stays in place throughout the course of treatment. This can be a:

  • central line
  • PICC line
  • portacath

If you don't have a central line

You might have treatment through a thin short tube (a cannula) that goes into a vein in your arm. You have a new cannula each time you have treatment.

How often do you have busulfan?

You usually have busulfan as cycles of treatment. This means that you have the drug and then a rest to allow your body to recover.

You usually have it as a course of several cycles of treatment. Each cycle varies depending on what type of cancer you have. Your doctor or nurse will tell you more about this.


You have blood tests before and during your treatment. They check your levels of blood cells and other substances in the blood. They also check how well your liver and kidneys are working.

What are the side effects of busulfan?

Side effects can vary from person to person. They also depend on what other treatments you're having. 

When to contact your team

Your doctor, nurse or pharmacist will go through the possible side effects. They will monitor you during treatment and check how you are at your appointments. Contact your advice line as soon as possible if:

  • you have severe side effects 

  • your side effects aren’t getting any better

  • your side effects are getting worse

Early treatment can help manage side effects better. 

Contact your advice line immediately if you have signs of infection, including a temperature above 37.5C or below 36C.

We haven't listed all the side effects here. Remember it is very unlikely that you will have all of these side effects. But you might have some of them at the same time.

Common side effects

These side effects happen in more than 10 in 100 people (more than 10%). You might have one or more of them. They include:

Increased risk of infection

Increased risk of getting an infection is due to a drop in white blood cells. Symptoms include a change in temperature, aching muscles, headaches, feeling cold and shivery and generally unwell. You might have other symptoms depending on where the infection is.

Infections can sometimes be life threatening. You should contact your advice line urgently if you think you have an infection. 

Bruising and bleeding

This is due to a drop in the number of platelets in your blood. These blood cells help the blood to clot when we cut ourselves. 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 petechiae).


You might be breathless and look pale due to a drop in red blood cells. This is called anaemia.

Allergic reaction

You might have an allergic reaction whilst having busulfan causing a skin rash, itching, swelling of the lips, face or throat, breathing difficulties, fever and chills. Tell your nurse or doctor immediately if at any time you feel unwell. They will give you medicine to help relieve your symptoms.

Lung changes

With high doses of busulfan, you may have a cough or feel breathless. There may be no sign of a infection. 

With lower doses of busulfan, you may have the same symptoms, alongside a high temperature. This is less likely. 

Let your team know if you’re feeling short of breath, feel as though your heart is beating fast or you have chest pain.

Feeling or being sick

Feeling or being sick is usually well controlled with anti sickness medicines. It might help to avoid fatty or fried foods, eat small meals and snacks and take regular sips of water. Relaxation techniques might also help.

It is important to take anti sickness medicines as prescribed even if you don’t feel sick. It is easier to prevent sickness rather than treat it once it has started.

Sickness is more common with high doses of busulfan.


Contact your doctor or pharmacist if you have indigestion or heartburn. They can prescribe medicines to help.

Hair loss

You could lose all your hair. This includes your eyelashes, eyebrows, underarms, legs and sometimes pubic hair. Your hair will usually grow back once treatment has finished but it is likely to be softer. It may grow back a different colour or be curlier than before. 


This drug might make you feel dizzy. Don’t drive or operate machinery if you have this.

Liver problems

You might have an enlarged liver, or high levels of a substance called bilirubin in the blood. This can cause jaundice – you might have yellowing of the skin or whites of the eyes. You might also have liver damage. This can all happen with high doses of busulfan. 

You’ll have regular blood tests to check how well your liver is working.

Feeling anxious

You might feel more worried or panicky than usual. Talk to your doctor or nurse about this if you do. 


Tell your doctor or nurse if you’re feeling depressed. They can arrange for you to talk to someone and give treatment if necessary.

Difficulty sleeping

If you have difficulty sleeping, it can help to change a few things about how you try to sleep. Try to go to bed and get up at the same time each day and spend some time relaxing before you go to bed. Some light exercise each day may also help. 

Diarrhoea or constipation

Tell your healthcare team if you have diarrhoea or constipation. They can give you medicine to help. 

Mouth sores and ulcers

Mouth sores and ulcers can be painful. It helps to keep your mouth and teeth clean, drink plenty of fluids and avoid acidic foods such as lemons. Chewing gum can help to keep your mouth moist. Tell your doctor or nurse if you have ulcers.

Loss of appetite

You might lose your appetite for various reasons while having cancer treatment. Sickness, taste changes or tiredness can put you off food and drinks.

You might lose weight but this is less common.


Tiredness and weakness (fatigue) can happen during and after treatment. Doing gentle exercises each day can keep your energy up. Don't push yourself, rest when you start to feel tired and ask others for help.

Changes to levels of substances in the blood

You might have high blood sugar levels, or low levels of other substances such as calcium, magnesium, albumin, sodium, potassium or phosphate.

You’ll have regular blood tests to check for this.


Tell your healthcare team if you keep getting headaches. They can give you painkillers to help.

Heart problems

This might be a change in heart rate or rhythm, such as a fast heart rate or flutter. Less commonly you might have an enlarged heart, inflammation of the sac around the heart or fluid build up around the heart.

Rarely, you might have extra heart beats.

Blood pressure changes

Blood clots

Blood clots can develop in the deep veins of your body, usually the leg. This is called deep vein thrombosis (DVT). A blood clot can be very serious if it travels to your lungs (pulmonary embolism), although this isn’t common.

Symptoms of a blood clot include:

•    pain, redness and swelling around the area where the clot is and may feel warm to touch
•    breathlessness
•    pain in your chest or upper back – dial 999 if you have chest pain
•    coughing up blood

Tell your doctor immediately or go to A&E if you have any symptoms of a blood clot.

Pain in different parts of the body

This might be pain in your back, joints, muscles, chest, tummy (abdomen) or around the anus. You might also have pain at the drip site if you are having busulfan into the vein (intravenously).

Skin problems

Skin problems include a skin rash, dry skin and itching, red patches on the skin, or peeling. Your nurse will tell you what products you can use on your skin to help.

Less commonly, you might have patches of skin darker than the surrounding skin (hyperpigmentation), or very fragile skin. You might have red patches in the corners of your mouth and you might sweat less than usual.

Kidney and bladder problems

You might have pain when passing urine, or you might be passing less urine than usual for you.

Less commonly you might have blood in your urine. This could be due to irritation to the lining of your bladder if you have had busulfan in combination with another drug called cyclophosphamide. Another problem could be that your blood tests might show changes to how well your kidneys are working.

Let your healthcare team know if you have any of the above symptoms. You’ll also have regular blood tests to check on how well your kidneys are working.

Fluid build up in different parts of the body

A build up of fluid may cause swelling in your arms, hands, ankles, legs, face, tummy (ascites) and other parts of the body. Contact your doctor if this happens to you.


You might get the hiccups with this drug. 

Periods stopping

Your periods might be irregular or stop if you are having high doses of busulfan. This can cause early menopause. 

Rarely, this can happen with lower doses of busulfan. 

Occasional side effects

These side effects happen in between 1 and 10 out of every 100 people (between 1 and 10%). You might have one or more of them. They include:

  • an increased risk of developing a blood cancer such as acute leukaemia

  • having blood in your sick

  • inflammation of the food pipe – you might find it painful or have difficulty swallowing or the feeling of food stuck in your throat

  • your intestines not being able to move and push food and waste out of your body, symptoms might include tummy pain or a swollen tummy and constipation

  • feeling confused

Rare side effects

This side effects happens in fewer than 1 in 100 people (fewer than 1%). You might have one or more of them. They include:

  • leaking of fluid and proteins out of the blood vessels into the tissues (capillary leak syndrome)

  • encephalopathy – you might feel very drowsy, confused or have problems remembering things

  • fits (seizures)

  • bleeding in the brain (cerebral haemorrhage)

  • feeling agitated or very nervous

  • seeing or hearing things that are not there (hallucinations)

Coping with side effects

We have more information about side effects and tips on how to cope with them.

What else do i need to know?

Other medicines, foods and drink

Cancer drugs can interact with some other medicines and herbal products. Tell your doctor or pharmacist about any medicines you are taking. This includes vitamins, herbal supplements and over the counter remedies.


Busulfan tablets contains lactose (milk sugar). If you have an intolerance to lactose, contact your doctor before taking this medicine.

Pregnancy and contraception

This drug may harm a baby developing in the womb. It is important not to become pregnant or father a child while you are having treatment with this drug and for at least 12 months afterwards. Talk to your doctor or nurse about effective contraception before starting treatment.

Loss of fertility

You may not be able to become pregnant or get someone pregnant after treatment with this drug. Talk to your doctor before starting treatment if you think you may want to have a baby in the future.

Men might be able to store sperm before starting treatment. And women might be able to store eggs or ovarian tissue. But these services are not available in every hospital, so you would need to ask your doctor about this.    


It is not known whether this drug comes through into the breast milk. Doctors usually advise that you don’t breastfeed during this treatment.

Treatment for other conditions

If you are having tests or treatment for anything else, always mention your cancer treatment. For example, if you are visiting your dentist.


Don’t have immunisations with live vaccines while you’re having treatment and for up to 12 months afterwards. The length of time depends on the treatment you are having. Ask your doctor or pharmacist how long you should avoid live vaccinations.

In the UK, live vaccines include rubella, mumps, measles, BCG, yellow fever and one of the shingles vaccines called Zostavax.

You can have:

  • other vaccines, but they might not give you as much protection as usual
  • the flu vaccine (as an injection)
  • the coronavirus (COVID-19) vaccine - talk to your doctor or pharmacist about the best time to have it in relation to your cancer treatment

Members of your household who are aged 5 years or over are also able to have the COVID-19 vaccine. This is to help lower your risk of getting COVID-19 while having cancer treatment and until your immune system Open a glossary item recovers from treatment.

Contact with others who have had immunisations - You can be in contact with other people who have had live vaccines as injections. Avoid close contact with people who have recently had live vaccines taken by mouth (oral vaccines) such as the oral typhoid vaccine. Sometimes people who have had the live shingles vaccine can get a shingles type rash. If this happens they should keep the area covered.

If your immune system is severely weakened, you should avoid contact with children who have had the flu vaccine as a nasal spray as this is a live vaccine. This is for 2 weeks following their vaccination.

Babies have the live rotavirus vaccine. The virus is in the baby’s poo for about 2 weeks and could make you ill if your immunity is low. Get someone else to change their nappies during this time if you can. If this isn't possible, wash your hands well after changing their nappy.

More information about this treatment

For further information about this treatment and possible side effects go to the electronic Medicines Compendium (eMC) website. You can find the patient information leaflet on this website.

You can report any side effect you have to the Medicines Health and Regulatory Authority (MHRA) as part of their Yellow Card Scheme.

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