Cytarabine into spinal fluid (intrathecal cytarabine)

Cytarabine is also known as Ara C or cytosine arabinoside.

Your doctor gives you the drug during a procedure called a ​lumbar puncture​. They inject cytarabine into the fluid around the spinal cord (cerebrospinal fluid or CSF). The drug mixes with the cerebrospinal fluid and circulates through the brain.

It is a treatment for:

• acute leukaemias (cancers of the blood)

• some lymphomas (cancers of the lymph glands)

Find 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.

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.

How do you have cytarabine 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.

Intrathecal injection

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

When do you have cytarabine into the spinal fluid?

The number of treatments may vary. Your doctor will tell you how often you need treatment.

Tests

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 cytarabine into the spinal fluid?

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. 

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.

Some of the side effects listed are more likely to happen if you are having cytarabine as a drip or injection into a vein than if you are having it in the spinal fluid.

Common side effects

Common side effects happen in more than 10 in 100 people (more than 10%). At the time of this review, there have been no reports of common side effects for this treatment.

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:

Breathlessness and looking pale

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

Increased risk of 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. This is known as petechiae.

Eye problems

You might have eye problems including burning, sore, red, itchy eyes (conjunctivitis).

You might also have vision problems or your eyes might be more sensitive to light. 

Tell your healthcare team if you have this. They can give you eye drops or other medication to help. 

Inflamed blood vessels

Your blood vessels might get inflamed. Symptoms include red spots on the skin, lumps or sores. Your legs and arms might also feel weak and numb. Contact your advice line or tell your doctor or nurse if you have any of these symptoms. 

High temperature (fever)

Tell your healthcare team straightaway if you get a high temperature. Ask them if you can take paracetamol to help lower your temperature.

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.

Inflammation at the site of injection

You might have some inflammation at the site of infection. This can cause swelling, redness and discomfort. Tell your healthcare team if this happens. 

Headaches

Tell your doctor or nurse if you have headaches. They can look into what is causing them and give you medicine to help.

Back pain

You might have back pain. Speak to your doctor if this is a problem for you. They can prescribe medicine to help.

Difficulty swallowing

Let your healthcare team know straight away if you have any problems swallowing.

Rare side effects

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

• whole body infection (sepsis) causing fever, being sick, confusion, dizziness and chills

• brown or black spots on the skin (lentigo)

• numbness, weakness or pain in lower arms or legs or pins and needles in your hands and feet

• loss of ability to move (paralysis of) legs and lower body

• inflammation of the sac surrounding the heart

• shortness of breath

• pain, burning, reddening and blistering of the palms of the hands and soles of the feet

• muscle and joint pain

Other side effects

If you have side effects that aren’t listed on this page, you can look at the cytarabine into the bloodstream page.

Coping with side effects

We have more information about side effects and tips on how to cope with them.

Read more about how to cope with side effects

What else do you need to know?

Other medicines, foods and drinks

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.

Loss of fertility

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.    

Contraception and pregnancy

This treatment may harm a baby developing in the womb. It is important not to become pregnant or get someone pregnant while you're having treatment and for at least 6 months afterwards.

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. 

Breastfeeding

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.

Immunisation

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, and yellow fever.

You can usually 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 a vaccine in relation to your cancer treatment.

Contact with others who have had immunisations 

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 ​immune system​ 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.

Read more about immunisations and cancer treatment

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.

eMC 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.

Report a side effect to the MHRA