Azacitidine
Azacitidine is a cancer drug. It may be used when a stem cell transplant is not possible for certain blood cancers.
What is azacitidine?
Azacitidine is a type of chemotherapy. It is best to read this information about azacitidine with our general information about chemotherapy and the type of blood cancer you have. Azacitidine may be given when a stem cell transplant is not possible to treat:
- myelodysplastic syndromes (MDS)
- acute myeloid leukaemia (AML)
- chronic myelomonocytic leukaemia (CMML), a rare blood disorder.
Your specialist blood cancer doctor (haematologist) will talk to you about this treatment and its possible side effects before you agree (consent) to have treatment.
This information is about azacitidine when it is given as an injection.
Onureg® is a tablet which contains azacitidine. It is used to keep AML in remission. Your blood cancer doctor or nurse can tell you more about this.
More information about this treatment
This information is correct at time of publishing. But sometimes the types of cancer this treatment is used for, or treatment side effects, may change between revision dates.
You can talk to your cancer team if you want more detailed information about this treatment. Or visit the electronic Medicines Compendium (eMC) website, which has patient information leaflets (PIL) for individual drugs.
How azacitidine is given
You will be given azacitidine in the chemotherapy day unit. A chemotherapy nurse will give it to you.
During your course of treatment, you will meet with someone from your cancer team, such as a:
- specialist blood cancer doctor (haematologist)
- chemotherapy nurse or specialist nurse specialist pharmacist.
This is who we mean when we mention doctor, nurse or pharmacist in this information.
Before or on the day of each treatment, you will have a blood test. This is to check that it is safe for you to have chemotherapy.
You will meet with a doctor, nurse or pharmacist before you have chemotherapy. They will talk to you about your blood results and ask how you have been feeling. If your blood results are okay, the pharmacy team will prepare your chemotherapy.
Your nurse will usually give you anti-sickness drugs before chemotherapy.
You have azacitidine as an injection under the skin (subcutaneously). It can be given in your tummy, upper arm or thigh.
Your course of chemotherapy
You usually have a course of several cycles of treatment over several months. Your cancer team will discuss your treatment plan with you.
Your nurse will give you the injections daily for 7 days. Then you have a rest period of 21 days. After this, you start another cycle of treatment in the same way. Some people may have the injections over a slightly different time.
About side effects
We explain the most common side effects of this treatment here. We also include some that are less common.
You may get some of the side effects we mention, but you are unlikely to get all of them. And you may have some side effects, including rarer ones, that we have not listed here.
Other cancer treatments may cause different side effects. If you are also having other cancer treatment, you may have other side effects.
Always tell your doctor, nurse or pharmacist about any side effects you have. They can give you:
- drugs to help control some side effects
- advice about managing side effects.
It is important to take any drugs exactly as explained. This means they will be more likely to work for you.
Serious and life-threatening side effects
Some cancer treatments can cause serious side effects. Sometimes, these may be life-threatening. Your doctor, nurse or pharmacist can explain the risk of these side effects to you.
Contact the hospital
Your doctor, nurse or pharmacist will give you 24-hour contact numbers for the hospital. If you feel unwell or need advice, you can call at any time of the day or night. Save these numbers in your phone or keep them somewhere safe.
Side effects while treatment is being given
Allergic reaction
Some people have an allergic reaction while having this treatment. Signs of a reaction can include:
- feeling hot or flushed
- shivering
- itching
- a skin rash
- feeling dizzy or sick
- a headache
- feeling breathless or wheezy
- swelling of your face or mouth
- pain in your back, tummy or chest.
Your nurse will check you for signs of a reaction during your treatment. If you feel unwell or have any of these signs, tell them straight away. If you do have a reaction, they can treat it quickly.
Sometimes a reaction happens a few hours after treatment. If you develop any of these signs or feel unwell after you get home, contact the hospital straight away on the 24-hour number.
Always call 999 if swelling happens suddenly or you are struggling to breathe.
Problems at the injection site
Azacitidine is given as an injection into the fatty tissue under the skin. This is called a subcutaneous injection. It may cause redness, itching, bruising and swelling where the injection is given (injection site).
This can be uncomfortable, but usually improves after several days. To reduce the irritation, your nurse will change the exact place they give you the injection. They can also give you advice on how to relieve any discomfort.
Very common side effects
Risk of infection
This treatment can reduce the number of white blood cells in your blood. These cells fight infection. If your white blood cell count is low, you may be more likely to get an infection. A low white blood cell count is called neutropenia.
An infection can be very serious when the number of white blood cells is low. Your doctor may give you antibiotics and other drugs to take during this treatment. These may help reduce your risk of getting an infection.
But it is still important to get any infection treated as soon as possible. If you have any of the following symptoms, contact the hospital straight away on the 24-hour number:
- a temperature above 37.5°C
- a temperature below 36°C
- you feel unwell, even with a normal temperature
- you have symptoms of an infection.
Symptoms of an infection include:
- feeling shivery and shaking
- a sore throat
- a cough
- breathlessness
- diarrhoea
- needing to pass urine (pee) often, or discomfort when you pass urine.
It is important to follow any specific advice your cancer treatment team gives you.
Your white blood cell count will usually return to normal before your next treatment. You will have a blood test before having more treatment. If your white blood cell count is low, your doctor may delay your treatment for a short time, until your cell count increases.
You may be given a drug called G-CSF. This encourages the body to make more white blood cells. You have it as a small injection under the skin.
Bruising and bleeding
This treatment can reduce the number of platelets in your blood. Platelets are cells that help the blood to clot.
If the number of platelets is low, you may bruise or bleed easily. You may have:
- nosebleeds
- bleeding gums
- heavy periods
- blood in your urine (pee) or stools (poo)
- tiny red, brown or purple spots that may look like a rash – these spots can be harder to see if you have black or brown skin.
If you have any unexplained bruising or bleeding, contact the hospital straight away on the 24-hour number. You may need a drip to give you extra platelets. This is called a platelet transfusion.
Anaemia (low number of red blood cells)
This treatment can reduce the number of red blood cells in your blood. Red blood cells carry oxygen around the body. If the number of red blood cells is low, this is called anaemia. You may feel:
- very low in energy
- breathless
- dizzy and light-headed.
If you have these symptoms, contact the hospital straight away on the 24-hour number. You may need treatment for anaemia. If you are very anaemic, you may need a drip to give you extra red blood cells. This is called a blood transfusion.
Feeling sick
Your doctor, nurse or pharmacist will prescribe anti-sickness drugs to help prevent or control sickness. Take the drugs exactly as they tell you to, even if you do not feel sick. It is easier to prevent sickness than to treat it after it has started.
If you feel sick, take small sips of fluid often and eat small amounts regularly. It is important to drink enough fluids. If you continue to feel sick, or if you are sick (vomit) 1 to 2 times in 24 hours, contact the hospital on the 24-hour number as soon as possible. They will give you advice. They may change your anti-sickness treatment. Let them know if you still feel sick.
Loss of appetite
This treatment can affect your appetite. Don’t worry if you do not eat much for 1 or 2 days. But if your appetite does not come back after a few days, or if you are losing weight, tell your doctor, nurse or pharmacist. They can give you advice. They may give you food or drink supplements. Or they may suggest changes to your diet or eating habits to help.
Diarrhoea
This treatment may cause diarrhoea. Diarrhoea means passing more stools (poo) than is normal for you, or having watery or loose stools. You may also have stomach cramps. If you have a stoma, it may be more active than usual.
If you are passing loose stools 3 or more times a day and this is not normal for you, contact the hospital as soon as possible on the 24-hour number. Follow the advice they give you about:
- taking anti-diarrhoea medicines
- drinking enough fluids to keep you hydrated and to replace lost salts and minerals
- any changes to your diet that might help.
They might also ask you for a specimen of your stool to check for infection.
Constipation
This treatment can cause constipation. Constipation means that you are not able to pass stools (poo) as often as you normally do. It can become difficult or painful. Here are some tips that may help:
- Drink at least 2 litres (3½ pints) of fluids each day.
- Eat high-fibre foods, such as fruit, vegetables and wholemeal bread.
- Do regular gentle exercise, like going for short walks.
If you have constipation, contact the hospital on the 24-hour number for advice. They can give you drugs called laxatives to help.
If you have not been able to pass stools for over 2 days and are being sick, contact the 24-hour number straight away.
Tummy pain
You may get pain in your tummy (abdomen), or have indigestion. Your doctor, nurse or pharmacist can give you advice or treatment to help. Contact the hospital straight away on the 24-hour number if your symptoms do not go away, or get worse.
Feeling tired
Feeling tired is a common side effect of this treatment. It is often worse towards the end of treatment and for some weeks after it ends. Try to pace yourself and plan your day so you have time to rest. Gentle exercise, like short walks, can help you feel less tired.
If you feel sleepy, do not drive or use machinery.
Headaches
This treatment may cause headaches. If you have headaches, tell your doctor. They may give you painkillers to help.
If your headache is severe, or you feel drowsy or have vision problems, contact your doctor straight away.
Muscle or joint pain
You may get pain in your muscles or joints for a few days after treatment. If this happens, tell your doctor or nurse. They can give you advice and painkillers. If the pain does not get better, tell your doctor or nurse. Having warm baths and taking regular rests may help.
Sore mouth and throat
This treatment may cause a sore mouth and throat. You may also get mouth ulcers. This can make you more likely to get a mouth or throat infection. Use a soft toothbrush to clean your teeth or dentures in the morning, at night and after meals.
Contact the hospital straight away on the 24-hour number, if:
- a sore mouth or throat affects how much you can drink or eat
- your mouth, tongue, throat or lips have any blisters, ulcers or white patches.
They can give you advice, and mouthwash or medicines to help with the pain or to treat any infection. Follow their advice and make sure you:
- drink plenty of fluids
- avoid alcohol and tobacco
- avoid food or drinks that irritate your mouth and throat.
Skin changes
This treatment may affect your skin. If your skin feels dry, try using an unperfumed moisturising cream every day. Always tell your nurse or doctor if you get a rash, itching skin or any other changes. They can give you advice and may prescribe creams or medicines to help.
Very rarely, this treatment can cause sores in the skin which can be serious. If you notice sores or broken areas of skin, tell your doctor or nurse straight away.
Hair loss
Your hair may get thinner. But you are unlikely to lose all the hair from your head. Hair loss usually starts after your first or second treatment. It is almost always temporary, and your hair will usually grow back after treatment ends.
Your nurse can talk to you about ways to cope with hair loss.
Effects on the kidneys
This treatment can affect how the kidneys work. This is usually mild and goes back to normal after treatment ends. You will have blood tests to check how well your kidneys are working. Contact the hospital on the 24-hour number if you:
- have blood in your urine (pee)
- are passing less urine or peeing less often than usual.
Drinking fluids helps protect your kidneys. The advice is usually to try to drink at least 2 litres (3½ pints) of fluid each day. But follow any advice from your doctor, nurse or pharmacist about how much is right for you.
Problems sleeping
This treatment can cause difficulty sleeping. Tell your doctor or nurse if this is a problem for you. There are some things you can do to try to improve your sleep. This includes having a regular bedtime hour and avoiding drinks containing caffeine.
Dizziness and anxiety
You may feel dizzy with this treatment. Some people may feel anxious, and sometimes people may become confused. Tell your doctor if you notice any of these side effects.
Effects on the lungs
This treatment can cause changes to the lungs. Tell your doctor, nurse or pharmacist if you develop:
- a cough that does not go away
- wheezing
- breathlessness.
You should also tell them if any existing breathing problems get worse. You may have tests to check your lungs.
Other side effects
Effects on the heart
This drug may cause fluid to build up around the heart. Less commonly, it can cause swelling around the heart.
Contact your cancer team or hospital straight away on the 24-hour number they have given you if you have any of these symptoms during or after treatment:
- pain or tightness in your chest that is worse when you breathe in
- feel breathless or dizzy
- feel your heart is beating too fast or too slowly
- have a high temperature, cough and flu like symptoms
Other conditions can cause these symptoms, but it is important to get them checked by a doctor. You may need tests to check how your heart is working.
Always call 999 if you have:
- chest pain, pressure, heaviness, tightness or squeezing across the chest
- difficulty breathing.
Changes in blood pressure
This drug can cause changes in your blood pressure. Your blood pressure may become lower or higher. Tell your doctor if you:
- feel dizzy when you stand up after sitting or lying down
- have headaches.
Bleeding in the eye or in the brain
This drug might cause bleeding in the eye or a bleed in the brain. Contact the hospital on the 24-hour number you have been given if you have:
- broken blood vessels or redness in your eye
- changes to your vision.
Contact the hospital on the 24-hour number you have been given straight away or call 999 if you have:
- a severe headache
- weakness in your body
- changes to your speech.
Tumour lysis syndrome (TLS)
Some people are at risk of developing a condition called tumour lysis syndrome (TLS). The risk is highest at the beginning of treatment. TLS happens when treatment makes large numbers of cancer cells die and break down quickly. This releases lots of waste products into the blood and can affect the kidneys and heart.
TLS can be prevented or treated. You will have regular blood tests to check for TLS. You may have:
- extra fluids through a drip
- medicines such as allopurinol tablets or rasburicase through a drip.
Drinking at least 2 litres (3½ pints) of fluid a day will also help.
Other information
Blood clot risk
Cancer and some cancer treatments can increase the risk of a blood clot. Contact the hospital straight away on the 24-hour number if you have any of these symptoms during or after treatment:
- throbbing pain or swelling in a leg or arm
- reddening of the skin in the area – if you have black or brown skin, this can be harder to notice, but the skin might become darker
- suddenly feeling breathless or coughing.
Always call 999 if you have:
- chest pain
- difficulty breathing.
A blood clot is serious, but it can be treated with drugs called anticoagulants. These thin the blood. Your doctor, nurse or pharmacist can give you more information about preventing and treating blood clots.
Other medicines
Some medicines can affect how this treatment works or be harmful while you are having it. Always tell your cancer doctor, nurse or pharmacist about any drugs you are taking or planning to take, such as:
- medicines you have been prescribed
- medicines you buy in a shop, pharmacy or online
- vitamins or supplements
- herbal drugs and complementary or homeopathic therapies
- recreational drugs – for example, cannabis.
Vaccinations
Doctors usually recommend that people with cancer have vaccinations for flu and for coronavirus (covid). These help reduce your risk of serious illness from these infections. Most people can have these vaccines, including people with weak immune systems.
If your immune system is weak, you should not have live vaccinations. Live vaccines can make you unwell because they contain a very weak version of the illness they will protect you against. Live vaccines include Zostavax®, which is a shingles vaccine, and the yellow fever vaccine.
It is important to ask your doctor, nurse or pharmacist for advice about having vaccinations. They can explain what vaccines are right for you and when it is best to have them.
Contraception
Breastfeeding
You are advised not to breastfeed while having this treatment, or for some time after treatment ends. This is because the drugs could be passed to the baby through breast milk.
Your doctor, nurse or pharmacist can give you more information.
Fertility
Some cancer drugs can affect whether you can get pregnant or make someone pregnant. If you are worried about this, it is important to talk with your doctor before you start treatment.
Sex
It is possible that small amounts of chemotherapy may be passed on through vaginal fluids or semen. If you have sex in the first few days after treatment, your cancer team will usually advise using condoms or a dental dam to protect your partner.
Medical and dental treatment
If you need medical treatment for any reason other than cancer, always tell the healthcare professional that you are having cancer treatment. Give them the contact details for your cancer doctor or cancer team so they can ask for advice.
If you have appointments with a dentist, always tell them you are having cancer treatment. Talk to your cancer team before you have any dental treatment.
About our information
This information has been written, revised and edited by Macmillan Cancer Support’s Cancer Information Development team. It has been reviewed by expert medical and health professionals and people living with cancer.
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References
Visit the electronic Medicines Compendium (eMC) to download a Patient Information Leaflet (PIL) for more detailed information. The leaflet lists all known side effects.
Date reviewed

Our cancer information meets the PIF TICK quality mark.
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