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Chemotherapy · Blood cancers

Cytarabine (Cytosar): What to Expect

Medically reviewed by Dr. Owais Mohammed, Medical Oncologist · Last reviewed September 2026

Cytarabine is a chemotherapy drug used in blood cancers including leukaemia and lymphoma. A name on a prescription with no explanation behind it is frightening. This page covers what cytarabine is, why the dose level your team has chosen matters, and — if you have been sent home with eye drops — why those are part of the plan.

Medically reviewed by Dr. Owais Mohammed, Medical Oncologist · Last reviewed September 2026

Prescription-only medicine.

Cytarabine is a prescription-only medicine given under the supervision of a specialist oncologist in a hospital or day-care unit. It cannot be started, adjusted or stopped on the basis of anything read online. It is not suitable for everyone — see who this is not for below.

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In short

Cytarabine, sold in India as Cytosar among other brands, is a chemotherapy drug used mainly for blood cancers such as leukaemia and lymphoma. Your oncologist will use either a standard dose or a much higher dose, and each has different side effects. At high doses, steroid eye drops are prescribed routinely to protect the eyes.

In detail

What is cytarabine and what is it used for?

Cytarabine — also called Ara-C and sold in India under brand names including Cytosar — is a chemotherapy drug that works by interfering with how cancer cells copy their DNA. Cells that cannot complete that process cannot divide, which is how the drug acts against the cancer.

It is used in blood cancers including acute myeloid leukaemia, acute lymphoblastic leukaemia, certain non-Hodgkin lymphomas, and chronic myelogenous leukaemia. Your oncologist will confirm which condition it is being used for in your case.

Cytarabine is always given in a hospital or day-care setting — as an intravenous infusion or, at some doses, as a subcutaneous injection. There is no tablet form.

In detail

What is the difference between standard-dose and high-dose cytarabine?

Cytarabine is used at two very different dose levels and they are not interchangeable. Standard-dose cytarabine is used in the early intensive phase of treatment for many blood cancers. High-dose cytarabine — sometimes called HiDAC — is typically used in consolidation, after an initial response has been achieved.

The distinction matters because the side effects differ. Standard dose mainly causes nausea, mouth sores and bone marrow suppression. High dose adds effects that do not appear at lower doses: cerebellar toxicity, which affects balance and coordination, and inflammation of the cornea, which is why eye drops are a required part of the high-dose protocol.

Your team will tell you which regimen you are having. The monitoring plan and the instructions before each cycle are specific to that dose level.

Eligibility

Who is cytarabine not suitable for?

Cytarabine is not used in every blood cancer, and not every person with an eligible condition will receive it. Eligibility is decided by an oncologist based on the individual case.

People with known hypersensitivity to cytarabine or to any component of the formulation
Pregnant womenCytarabine is known to harm a developing baby. Effective contraception is required during treatment for anyone who could become pregnant.
People who are breastfeeding
Patients with severely impaired liver function, where the drug may not be safely cleared from the body
Those with severely compromised bone marrow function where further suppression cannot be safely managed

High-dose regimens carry additional risks — including effects on the cerebellum and on the eyes — that make them unsuitable for people with pre-existing neurological conditions, significantly reduced performance status, or severely impaired kidney function. Your oncologist will assess your individual situation before recommending any cytarabine regimen.

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In detail

Why am I being given eye drops with cytarabine?

At high doses, cytarabine reaches the fluid inside the eye and can cause chemical inflammation of the cornea — the clear surface at the front of the eye. This is called cytarabine-induced keratoconjunctivitis. Without prevention, it causes red, painful, gritty eyes and sensitivity to light.

Steroid eye drops — usually a prednisolone or dexamethasone preparation — are prescribed to prevent this. You will be asked to start them before your infusion begins and to continue on the schedule given throughout the treatment days and for a short period after the last dose of each cycle.

The timing matters. Use the drops at the intervals you have been given, even if your eyes feel completely normal. If your eyes become red, gritty or painful despite using the drops correctly, tell your team the same day — this is not something to watch and wait on.

Checklist

Which symptoms should I tell my team about the same day?

Any fever during or after treatment — even a mild one
Difficulty walking, loss of balance, or shaking hands
Red, painful or gritty eyes
Mouth sores that make it painful to eat or drink
Unusual bruising or bleeding anywhere
Skin rash combined with fever or joint and bone pain
Confusion or difficulty speaking clearly

Worth knowing

Did you know?

Cytarabine has been part of treatment for acute leukaemia for more than fifty years and remains a backbone of current induction and consolidation regimens in NCCN and ESMO guidelines. The eye drops given at high dose are not an add-on — they are a required element of the protocol, because corneal inflammation occurs in a proportion of patients who do not receive them.

Source: NCCN Clinical Practice Guidelines in Oncology: Acute Myeloid Leukemia; ESMO Clinical Practice Guidelines for haematological malignancies

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Common questions

Frequently asked questions

Why am I prescribed eye drops — I am not having eye treatment?

At high doses, cytarabine reaches the fluid inside the eye and causes chemical inflammation of the cornea, a condition called keratoconjunctivitis. Your eyes become red, gritty and sensitive to light, and in some cases vision is affected. Steroid eye drops — typically prednisolone or dexamethasone — are given before, during and after each infusion to prevent this. They are not treating an existing eye problem; they are protecting your eyes from a predictable effect of the dose you are receiving. If you have a pre-existing eye condition, tell your team before treatment begins so that the approach can be planned appropriately.

What is the difference between standard-dose and high-dose cytarabine?

Standard-dose cytarabine is used in the initial intensive phase of treatment and mainly causes nausea, mouth sores and bone marrow suppression. High-dose cytarabine delivers much larger amounts and is typically used in consolidation. It produces additional effects that do not appear at lower doses: cerebellar toxicity affecting balance and coordination, corneal inflammation requiring eye drops, and Ara-C syndrome — a reaction that can include fever, bone pain and rash. These are managed differently, and the monitoring your team schedules will reflect whichever dose level you are on.

Will cytarabine make my hair fall out?

Hair loss is reported less commonly with cytarabine than with some other chemotherapy drugs, though it can occur. What you are more likely to notice is mouth sores, fatigue, nausea and a significant drop in blood counts in the days after each cycle. Your hair experience may also depend on what other drugs are being given alongside cytarabine, as it is often part of a combination regimen. Ask your team what to expect from the specific combination prescribed for you.

When will my blood counts drop and when will they recover?

Bone marrow suppression is expected with cytarabine. White cell and platelet counts typically reach their lowest point roughly one to two weeks after each cycle, though the exact timing depends on the dose and the full regimen. Your team will schedule blood tests to monitor this closely. When your white cell count is at its lowest, you are most vulnerable to infection, which is why any fever must be reported the same day rather than managed at home. Recovery follows in most cases, and your next cycle is usually timed around it.

Can I eat normally during cytarabine treatment?

Mouth sores are common, particularly at higher doses, and can make eating painful. Soft, bland foods that do not irritate the mouth lining usually help. Nausea is manageable with the anti-sickness medicine your team prescribes — take it on the schedule given rather than waiting until you feel unwell. Staying well hydrated matters because cytarabine is cleared through the kidneys. Tell your team if you cannot eat or drink normally, because dehydration alongside chemotherapy makes other side effects harder to manage.

How long does each cytarabine infusion or cycle take?

The length of each session depends on the dose level and the regimen. Standard-dose cytarabine can be given as a relatively short infusion or as a continuous infusion over several days. High-dose cytarabine is typically given as multiple infusions over consecutive days, followed by rest days before the next cycle. Your oncologist or the nursing team will explain exactly what each hospital admission or day-care visit involves. The overall number of cycles depends on your disease, your response to treatment, and the aim of the regimen.

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