Cancer drugs A to Z list
Cytarabine is a type of chemotherapy. You pronounce it as sye-ta-ra-bin.
Cytarabine is also known as Ara C or cytosine arabinoside.
Your doctor gives you the drug during a procedure called a . They inject cytarabine into the fluid around the (cerebrospinal fluid or CSF). The drug mixes with the cerebrospinal fluid and circulates through the brain.
It is a treatment for some:
acute leukaemias (cancers of the blood)
some lymphomas (cancers of the lymph glands)
Find your cancer type on our A-Z list
Cytarabine is a type of chemotherapy drug called an It kills cancer cells by stopping them from making and repairing DNA that they need to grow and multiply.
You might have cytarabine into the spinal fluid if there are cancer cells there. You might also have it as prevention, in case cancer cells get into the spinal fluid.
Cytarabine is a clear liquid. An experienced cancer doctor injects it into the fluid around the spinal cord during a lumbar puncture.
You have an intrathecal injection of cytarabine the same way you have a lumbar puncture. You lie on your side. Your doctor gives you a small injection to numb an area in your back. They then inject the cytarabine between 2 of your spinal bones into the spinal fluid. It takes from 1 to 5 minutes. Afterwards you need to lie flat for an hour.
Find out more about having a lumbar puncture
You can also have cytarabine as an injection:
into your bloodstream (intravenously)
just under the skin (subcutaneously)
Get more information on having cytarabine as an injection
The number of treatments may vary depending on your cancer type. Your doctor will tell you how often you need treatment.
You have blood tests before and during your treatment. They check your levels of and other substances in the blood. They also check how well your liver and kidneys are working.
Before treatment starts you may have a blood test to check for viruses such as hepatitis B, hepatitis C, and HIV. This is called a viral screen.
It’s important for your doctor to know if you have had any of these viruses. This is because this treatment can weaken your and can cause the virus to become active again (reactivation).
Side effects can vary from person to person. They also depend on what other treatments you're having.
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.
We haven't listed all the side effects here. Talk to your healthcare team if you have any new symptoms that you think might be a side effect of your treatment.
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.
You might have one or more of these side effects. They include:
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.
Tell your healthcare team straight away if you get a high temperature. Ask them if you can take paracetamol to help lower your temperature.
Let your doctor or nurse know if you have headaches. They can give you painkillers such as paracetamol to help.
You might develop numbness and loss of ability to move (paralysis) of your legs and lower body. Tell your doctor straight away of you notice this.
If you have side effects that aren’t listed on this page, you can look at the cytarabine into the bloodstream page.
We have more information about side effects and tips on how to cope with them.
Cancer drugs can interact with medicines, herbal products, and some food and drinks. We do not list these interactions on this page. 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 if you have any other medical conditions or allergies.
This drug may harm a baby developing in the womb. It is important not to become pregnant or get someone pregnant while you are having treatment with this drug and for at least 6 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 become pregnant while having treatment.
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.
If you are having tests or treatment for anything else, always mention your cancer treatment. For example, if you are visiting your dentist.
Do not have live vaccines while you’re having treatment and for up to 12 months afterwards. For some people, it may be longer than this. The length of time you need to avoid live vaccines depends on the treatment you’ve had.
Ask your doctor or pharmacist how long you should avoid live vaccinations.
In the UK, live vaccines include rubella, mumps, measles, chickenpox, BCG, and yellow fever. You can usually have non-live vaccines. But they might not give you as much protection as usual. These include the:
flu vaccine, as an injection
coronavirus (COVID-19) vaccine
Talk to your doctor or pharmacist about the best time to have a vaccine in relation to your cancer treatment.
You can be in contact with other people who have had live vaccines as injections. If someone has had a live vaccine by mouth or nasal spray there may be a small risk the vaccine virus can be passed onto you if your is weakened.
Your healthcare team will let you know if you need to take any precautions if you are in close contact with someone who has had a live vaccine.
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 and Healthcare products Regulatory Agency (MHRA) as part of their Yellow Card Scheme.
Last reviewed: 04 Nov 2026
Next review due: 04 Nov 2029
Search for the cancer type you want to find out about. Each section has detailed information about symptoms, diagnosis, treatment, research and coping with cancer.
Chemotherapy is a standard treatment for some types of cancer. It uses anti cancer drugs to destroy cancer cells.
Coping with cancer can be difficult. There is help and support available. Find out about the emotional, physical and practical effects of cancer and how to manage them.
Cancer drugs have side effects and these can vary from person to person. But there are things that you can do to help you cope.
