Cytarabine (Ara C, cytosine arabinoside)

What is cytarabine?

Cytarabine is a type of chemotherapy. You pronounce cytarabine sye-ta-ra-bin. It’s also known as Ara C or cytosine arabinoside.

It is a treatment for some types of:

• acute leukaemia (cancer of the blood)

• lymphoma (cancer of the lymph glands)

• myelodysplastic syndromes (MDS)

• myeloproliferative neoplasms

You might have cytarabine before a stem cell transplant or as part of a clinical trial.

You might have cytarabine on its own or in combination with other cancer drugs and radiotherapy.

Find out more about treatment for your cancer type on our A-Z list

How does cytarabine work?

Cytarabine is a type of chemotherapy drug called an ​anti metabolite​. It kills cancer cells by stopping them from making and repairing DNA that they need to grow and multiply.

How do you have cytarabine?

How you have cytarabine depends on what type of cancer you have. You can have it as an injection:

• into your bloodstream (intravenously)

• just under the skin (subcutaneously)

• into your spinal fluid (intrathecal injection)

Injection under your skin (subcutaneous injection)

You usually have injections under the skin (subcutaneous injection) into the stomach.

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.

Chemotherapy into the spinal fluid (intrathecal chemotherapy)

You might have chemotherapy injected into the fluid around the spinal cord (cerebrospinal fluid or CSF). This is called intrathecal chemotherapy. 

Your doctor gives you the drug during a procedure called lumbar puncture. The drug mixes with the cerebrospinal fluid and circulates through the brain.

Find out more about having cytarabine into spinal fluid

When do you have cytarabine?

You usually have cytarabine as a course of several cycles of treatment. A cycle of treatment means that you have this drug and then have a rest to allow your body to recover.

Each cycle varies depending on what type of cancer you have. Your doctor or nurse will tell you more about this.

What are the side effects of cytarabine?

Liver changes

You might have liver changes that are usually mild and unlikely to cause symptoms. They usually go back to normal when treatment finishes.

Some people develop jaundice with this treatment but it isn’t known how often this happens. Let your healthcare team now if you have yellowing of the skin or whites of the eyes.

You have regular blood tests to check for any changes in the way your liver is working.

Skin changes

You might notice skin changes such as a rash.

Less commonly you might develop fluid filled blisters or a raised itchy rash (hives). Your skin might go red (erythema) if you have a white skin. On black or brown skin this may look purple or darker than your normal skin.

Rarely you might have skin ulcers or lentigo. Lentigo is darker patches of skin that are flat or slightly raised. The skin on your hands and feet may become sore, red or may peel. You may also have tingling, numbness, pain and dryness. This is called hand-foot syndrome or palmar plantar syndrome.

Other skin changes include freckles, bleeding under the skin caused by small blood vessels leaking and Ara-C ears. Ara-C ears is when the ears get bright red and swollen. It is not known how often these side effects happen.

Tell your healthcare team of any skin changes. They can give you medicine to help and advise you on what products to use on your skin.

• hair loss

• a high temperature (fever)

• pain in the tummy (abdomen), rarely you might have muscle and joint pain

• feeling or being sick

• diarrhoea

• a sore mouth and ulcers. More rarely you may get a sore throat

• inflammation and ulcers at the opening at the end of the bowel (anus), more rarely this may happen to your food pipe (oesophagus). Let your healthcare team know if you have pain, bowel movement changes, feeling or being sick, indigestion, difficulty swallowing, blood in your sick or poo, the urge to poo or mucus in your poo

• swallowing problems (dysphagia)

• a blood clot at the injection site. Some people might develop redness and swelling at site of injection – but it is not known how often this happens

• kidney problems – such as changes to blood tests and finding it difficult to fully empty your bladder (urinary retention)

• eye problems - your eyes may feel gritty, itchy, sticky with pus, watery, red or have burst blood vessels in the eye. You might have eye pain, blurred vision, be sensitive to bright lights and feel as though something is in your eye

• loss of appetite

• high levels of uric acid in the blood – you have regular blood tests to check this

• inflammation of your blood vessels – symptoms can vary depending on which blood vessels are affected - general symptoms include feeling very tired, loss of appetite, weight loss, a high temperature, aches and pains

• a headache

• gas in the bowel wall – symptoms can include discomfort or pain in your tummy (abdomen), swollen abdomen, weight loss, being sick, diarrhoea or constipation

• heart problems such as inflammation of the sac around the heart and heart rhythm changes. Symptoms of heart problems can include shortness of breath, chest pain or discomfort, you might feel your heart pound, race or flutter, feel dizzy or lightheaded and feel tired. Let your healthcare team know if you have any of these symptoms

• shortness of breath – let your healthcare team know if you have this

• an allergic reaction that can cause a rash, shortness of breath, redness or swelling underneath the skin in areas such as the hands, feet, lips, tongue, around the eyes or genitals (angioedema). Some allergic reactions can be life threatening - alert your nurse if you notice any of these symptoms

• damage to nerve tissues and inflammation of the nerves and parts of the nervous system

• dizziness

• blood in your poo or black tarry looking poo – this could be a sign of a problem in your digestive system, let your healthcare team know about this

• inflammation of the pancreas (pancreatitis) - symptoms include severe tummy pain, feeling or being sick, a high temperature or diarrhoea

• chest pain

• inflammation of the sweat glands – you may get pain and tender areas of skin

Possible additional side effects if you have high dose cytarabine treatment

You might have additional side effects from high dose cytarabine. Any other side effects may also be more severe. Ask your healthcare team if you are having high dose cytarabine if you are not sure.

Common side effects

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

• changes to nerves, movement, thinking and emotions - symptoms can include balance and coordination problems, your speech might be slurred or you may have voice changes. You may be less focused and have changes in your mood and behaviour

• feeling very tired or find you are falling asleep during the day. Do not drive or operate machinery. Let your doctor know straight away

• fluid in the lungs (pulmonary oedema). The fluid stops your lungs expanding fully. So, you have to take shallower breaths and make more effort to breathe. Talk to the team looking after you if you are breathless or finding it difficult to breathe

• inflammation of the lungs due to infection or damage - symtpoms include fast and shallow breathing, tiredness, drowsiness, confusion, feeling like you might faint and shortness of breath. This is called acute respiratory distress syndrome (ARDS). It causes a lack of oxygen to your organs such as the lungs, heart and brain

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:

• rapid and uncontrollable eye movements side to side or up and down

• peeling of the skin

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 infection of the lining of the tummy (peritonitis) – symptoms can include a high temperature, chills, pain, a fast heartbeat, not being able to pee or peeing less than usual, feeling sick and a swollen tummy

• numbness or tingling in fingers or toes (peripheral neuropathy) is often temporary and can improve after you finish treatment

• inflammation and death of your bowel (necrotising colitis) – this is a life-threatening condition, let your healthcare team know straight away if you have diarrhoea, severe pain in your tummy, have blood in your poo, feel or are being sick, have a high temperature and a swollen tummy

Other side effects

There isn't enough information to work out how often these side effects might happen. You might have one or more of them. They include:

• changes in how awake or alert you are

• fits (seizures)

• long term disease of the heart muscle (cardiomyopathy) - this can be life threatening

• a condition that causes your muscles to breakdown (rhabdomyolysis) - this can be serious if not treated quickly. Symptoms include muscle pain or weakness, dark urine, tiredness, dehydration and confusion

• liver changes - symptoms may include yellowing of the skin or eyes, feeling or being sick, bleeding or bruising, dark pee, swollen liver and stomach pain

• periods stopping (amenorrhoea)

• low sperm count

• tremor (shaking)

• feeling confused

• a sore or ulcer on the outer surface of the eye (cornea)

What else do you need to know?

Pregnancy and contraception

This treatment may harm a baby developing in the womb. It is important not to become pregnant or get someone pregnant while you are having treatment.

Women must not become pregnant for at least 6 months after the end of treatment.

Men should not get someone pregnant 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 becomes pregnant while having treatment.

Breastfeeding

It is not known whether this drug comes through into the breast milk. Doctors usually advise that you don’t breastfeed for 1 week after your last treatment.