Azacitidine (Vidaza) | Cancer Research UK
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Azacitidine (Vidaza)

This page tells you about the cancer treatment drug azacitidine and its possible side effects. There is information about


What azacitidine is

Azacitidine is pronounced ay-sah-sit-a-dean. It is also called Vidaza. It is a treatment for people who can’t have high dose treatment with a stem cell transplant for the following conditions

  • Chronic myelomonocytic leukaemia (CMML)
  • Acute myeloid leukaemia
  • Myelodysplastic syndrome

How azacitidine works

Azacitidine is a type of drug called a hypomethylating agent. It works by switching off a protein called DNA methyltransferase. This switches on genes that stop the cancer cells growing and dividing. This reduces the number of abnormal blood cells and helps to control cell growth.


How you have azacitidine

You usually have azacitidine as an injection just under your skin (subcutaneously) given by a doctor or nurse. This can be in your upper arm, leg, buttock or stomach. 

We have information about having an injection just under the skin (subcutaneously).

You usually have azacitidine as a course of several cycles of treatment. You have treatment each day for a week and then 3 weeks with no treatment. This makes up a treatment cycle. You usually have at least 6 cycles and the treatment continues for as long as it is working.

The side effects associated with azacitidine are listed below. Many people find that the side effects are worse with the first 2 cycles of treatment. You can use the links to find out more about each effect. For general information, 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.

  • 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)
  • Feeling or being sick happens in about 5 out of 10 people (50%) but is usually well controlled with anti sickness medicines
  • Tiredness and weakness (fatigue) affects 4 in 10 people (40%) during and after treatment. Some people find their energy levels are back to normal within 6 months to a year. But some people with myelodysplastic syndrome may continue to be tired. If you are very tired, take care when operating machinery or driving
  • Irritation, including redness, around the area of the injection – make sure you don’t have the injection in the same place twice. Don’t have it in an area that is bruised or sore
  • A skin rash, which may be itchy
  • Diarrhoea affects just under 4 out of 10 people (40%) – drink plenty of fluids. Tell your doctor or nurse if diarrhoea becomes severe, or continues for more than 3 days
  • Constipation occurs in about 4 out of 10 people (40%) – 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 appetite affects about 2 out of 10 people (20%)
  • A cough and shortness of breath or chest pain due to a chest infection
  • Headaches
  • Dizziness
  • 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
  • Aching joints
  • A sore nose and throat
  • Tummy (abdominal) pain

Occasional side effects

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

  • Mood changes, including feeling anxious or confused
  • A sore mouth
  • Indigestion
  • Muscle aches and pains
  • Blood in your urine
  • Difficulty sleeping
  • Low levels of potassium in your blood (hypokalaemia) – you will have blood tests to check the levels of potassium
  • Feeling weak, a high temperature and chills
  • Infections – including urine infections
  • Cold sores (herpes) caused by a viral infection
  • Redness of the skin
  • Bleeding – there is a small increase in risk of bleeding. This may be in your bowel, stomach, eyes or brain. Tell your nurse or doctor straight away if you have a headache, sudden dizziness, vomit any blood, or there is blood in your stool
  • High or low blood pressure (hypertension or hypotension)
  • Weight loss
  • General weakness
  • Hair loss – your hair may thin during treatment. It will grow back once the treatment ends
  • Kidney changes – you will have regular blood tests to check how well your kidneys are working. Let your doctor or nurse know straight away if the amount of urine you pass is less than usual
  • A stuffy nose – caused by inflamed sinuses
  • Pain in your throat or voicebox
  • Indigestion

Rare side effects

Fewer than 1 in 100 people have these.

  • Liver changes – the liver will almost certainly go back to normal when treatment finishes. You will have regular blood tests to check how well your liver is working
  • Some people have an allergic reaction while having azacitidine treatment, usually at the first or second treatment. Let your treatment team know straight away if you feel hot or have any skin rashes, itching, dizziness or headaches. Also tell them if you have shivering, breathlessness, anxiety, flushing of the face, or a sudden need to pass urine
  • Shaking
  • Drowsiness – do not drive or operate machinery if you have this

Important points to remember

You may have a few of the side effects mentioned on this page. 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)
  • 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

This drug may have a harmful effect on a developing baby. You must use effective contraception if there is any risk that you or your partner could become pregnant. Continue using contraception for at least 3 months after the end of treatment. Talk to your doctor or nurse about contraception before starting the treatment.


Breastfeeding is not advisable during this treatment because the drug may come through in the breast milk.


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 azacitidine

Azacitidine is a relatively new drug in cancer treatment. This means that there is limited information about side effects, especially possible longer term effects. If you notice anything that is not normal for you tell your doctor or nurse.

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


Related information

We have information about the following cancers and conditions 

Chronic myelomonocytic leukaemia (CMML)

Acute myeloid leukaemia

Myelodysplastic syndrome

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Updated: 16 February 2015