Azacitidine (Vidaza, Onureg)

Azacitidine is a type of chemotherapy drug. It is also known as Vidaza or Onureg.

It is a treatment for people who can’t have high dose treatment with a stem cell transplant Open a glossary item or bone marrow transplant Open a glossary item for the following conditions:

  • chronic myelomonocytic leukaemia (CMML)
  • acute myeloid leukaemia (AML)
  • myelodysplastic syndrome

If you have AML you might have azacitidine with another drug called venetoclax. Venetoclax is a type of targeted cancer drug.

You pronounce azacitidine as ay-za-sye-ta-deen.

How does azicitidine work?

Azacitidine is a type of chemotherapy called an anti metabolite. It stops cells making and repairing DNA Open a glossary item. Cancer cells need to make and repair DNA so they can grow and multiply.

How do you have azacitidine?

You usually have azacitidine as an injection just under your skin (subcutaneously). Your doctor or nurse gives you the injection.

Some people with AML might take azacitidine as a tablet.

Injection under your skin (subcutaneous injection)

You usually have injections under the skin (subcutaneous injection) into the stomach, thigh or top of your arm.

You might have stinging or a dull ache for a short time after this type of injection but they don't usually hurt much. The skin in the area may go red and itchy for a while.

Your next injection is usually in a different place and at least 2.5 cm from the previous injection site.

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.

How often do you have azacitidine?

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

Each cycle of treatment lasts 28 days (4 weeks). The number of cycles varies depending on if you have azacitidine as an injection on its own, with venetoclax or if you are taking it as tablets.

Your healthcare team can let you know your treatment plan.

This is an example of having azacitidine as an injection:

Day 1 to day 5
  • You have azacitidine as an injection under the skin.
Day 6 and day 7
  • You have no treatment.
Day 8 and day 9
  • You have azacitidine as an injection under the skin.
Day 10 to day 28
  • You have no treatment.

You then start a new cycle of treatment.

This is an example of having azacitidine as a tablet:

Day 1 to day 14
  • You take azacitidine as tablets once a day - swallow it whole with plenty of water.
Day 15 to day 28
  • You have no treatment.

You then start a new cycle of treatment.


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 azacitidine?

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.

The following side effects are based on you having azacitidine as an injection. The side effects may be different if you are taking azacitidine as a tablet. Speak to you doctor, nurse or pharmacist for more information. 

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:


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

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).

Less commonly azacitidine can cause bleeding from other parts of the body. This includes passing blood in your wee (urine) or poo; bleeding in the brain; bleeding in the eyes; bleeding into the skin (haematoma) or you might also notice blood in your mouth and from your gums.

Let your healthcare team know straight away if you notice you have any signs of bleeding.

High temperature

If you get a high temperature, let your healthcare team know straight away. Ask them if you can take paracetamol to help lower your temperature.

Lung problems

You commonly develop shortness of breath with azacitidine. This could also happen when you move, but this is less common. Shortness of breath could be due to infection, such as pneumonia. Less commonly, it could be due to fluid build up around the lung.

Let your doctor or nurse know straight away if you suddenly become breathless or develop a cough.

Inflammation of the nose and throat

Your nose and throat could become swollen and sore.

Loss of appetite and weight loss

You might not feel like eating and may lose weight. Eating several small meals and snacks throughout the day can be easier to manage. You can talk to a dietitian if you are concerned about your appetite or weight loss. 

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. 


Let your doctor or nurse know if you have headaches. They can give you painkillers such as paracetamol to help.


This drug might make you feel dizzy. You might also feel dizzy when standing or moving around. Or it might feel like the world is spinning.

Don’t drive or operate machinery if you have this.

Diarrhoea or constipation 

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

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.

Tummy (abdominal) pain

Tell your treatment team if you have this. They can check the cause and give you medicine to help. 

Skin problems

Skin problems include a skin rash, dry skin and itching. You may also have reddening of the skin but this is less common.

Rarely azacitidine can cause skin conditions such as:

  • acute febrile neutrophilic dermatosis - symptoms include high temperature (fever) with large plum coloured, raised painful patches on your skin
  • pyoderma gangrenosum that causes painful skin ulcers

Skin changes usually go back to normal when your treatment finishes. Your healthcare will tell you what products you can use on your skin to help.

Joint, muscle and bone pain

You might have pain from your muscles, joints, bones, or back. Speak to your doctor, nurse or pharmacist about what painkillers you can take to help with this.


You might feel very tired and as though you lack energy.

Various things can help you to reduce tiredness and cope with it, for example exercise. Some research has shown that taking gentle exercise can give you more energy. It is important to balance exercise with resting.

Chest pain

You might get pain in your chest. Contact your advice line or tell your doctor if this happens. 

Redness, pain and swelling at the injection site

Tell your nurse if you have any pain or notice any signs of redness, irritation or bleeding around the injection site.

Changes to the levels of substances in your blood

It is common for azacitidine to cause low levels of potassium in the blood (hypokalaemia). Let your doctor or nurse know if you have cramping in your arm or leg muscles, tingling or numbness, palpitations (feeling your heart beat irregularly), or if you feel faint.

Less commonly your blood tests might show that you have high levels of a substance called creatinine. Creatinine is a protein made by the muscles. The kidneys remove them from our bodies and get rid of them in the urine.

You have regular blood tests to check these levels in your blood.

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:

  • your bone marrow Open a glossary item not being able to make blood cells Open a glossary item
  • not enough fluid in your body (dehydration)
  • feeling confused or anxious
  • fainting
  • fluid around your heart - this could affect how your heart works
  • sleepiness and lethargy
  • high blood pressure that might cause headaches, confusion, vision problems or chest pain
  • low blood pressure that can cause you to feel lightheaded or dizzy, sometimes this can happen when you stand up from sitting or lying down (orthostatic hypotension)
  • indigestion symptoms include heartburn, bloating, and burping
  • hair loss
  • uncontrolled muscle movement (spasms)
  • your kidneys not working properly symptoms might include confusion, not passing enough urine and shortness of breath
  • sore mouth and ulcers
  • generally feeling unwell
  • shivering (chills)

Rare side effects

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

  • an allergic reaction that can cause a rash, shortness of breath, redness or swelling of the face and dizziness - some allergic reactions can be life-threatening alert your nurse or doctor if notice any of these symptoms
  • shaking
  • your liver not working (liver failure)
  • inflammation of the lining of the heart
  • changes to the levels of chemicals in your blood due to the breakdown of tumour cells (tumour lysis syndrome) - you have regular blood tests to check for this

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, food and drink

Cancer drugs can interact with medicines, herbal products, and some food and drinks. We are unable to list all the possible interactions that may happen. An example is grapefruit or grapefruit juice which can increase the side effects of certain drugs.

Tell your healthcare team about any medicines you are taking. This includes vitamins, herbal supplements and over the counter remedies. Also let them know about any other medical conditions or allergies you may have.

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.

Women must not become pregnant for at least 6 months after the end of treatment. Men should not father a child for at least 3 months after treatment. 

Talk to your doctor or nurse about effective contraception before starting treatment. Let them know straight away if you or your partner falls pregnant while having treatment.

Loss of fertility

It is not known whether this treatment affects fertility Open a glossary item in people. Talk to your doctor before starting treatment if you think you may want to have a baby in the future.


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.

  • Electronic Medicines Compendium
    Accessed January 2023

  • Immunisation against infectious disease: Chapter 6: General contraindications to vaccination
    Public Health England
    First Published: March 2013 and regularly updated on the Gov.UK website

  • Azacitidine for the treatment of myelodysplastic syndromes, chronic myelomonocytic leukaemia and acute myeloid leukaemia
    National Institute for Health and Care Excellence, March 2011

  • Oral azacitidine for maintenance treatment of acute myeloid leukaemia after induction therapy
    National Institute for Health and Care Excellence, October 2022

  • Venetoclax with azacitidine for untreated acute myeloid leukaemia when intensive chemotherapy is unsuitable
    National Institute for Health and Care Excellence, February 2022

  • The information on this page is based on literature searches and specialist checking. We used many references and there are too many to list here. Please contact with details of the particular issue you are interested in if you need additional references for this information.

Last reviewed: 
23 Jan 2023
Next review due: 
23 Jan 2026

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