Asparaginase (Crisantaspase, Erwinase) | Cancer Research UK
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Asparaginase (Crisantaspase, Erwinase)

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This page tells you about the chemotherapy drug asparaginase and its possible side effects. It is also called Crisantaspase and Erwinase. There is information about


What asparaginase is

Asparaginase is a chemotherapy drug used to treat acute lymphoblastic leukaemia (ALL). It can also be used to treat some other blood disorders. It also has the names Erwinase, Crisantaspase or L-asparaginase. 

One form of asparaginase is made from a type of bacteria called escherichia coli. Another form of asparaginase is made from Erwinia chrysanthemi bacteria. 


How asparaginase works

Asparaginase is an enzyme that breaks down a chemical in cancer cells. The cells need this chemical to make protein to create new cells. So asparaginase stops the cancer cells from dividing and growing. 


How you have asparaginase

You may have asparaginase as an injection into a vein (IV) or as an injection just under the skin. But you are more likely to have it as a series of injections into a muscle in your arm or leg (IM).

Your doctor will decide what dose you need, how often you will have it, and how long you need it for. It varies according to your body weight, your specific type of leukaemia and how quickly it works.


Tests during treatment

You have blood tests before starting treatment and regularly during your treatment. The tests check your levels of blood cells and other substances in the blood. They also check how well your liver and kidneys are working.


About side effects

We've listed the side effects associated with asparaginase. You can use the links to find out more about each side effect. Where there is no link, please go to our information about cancer drug side effects or use the search box at the top of the page.

You may have a few side effects. They may be mild or more severe. A side effect may get better or worse through your course of treatment. Or more side effects may develop as the course goes on. This depends on

  • How many times you've had the drug before
  • Your general health
  • The amount of the drug you have (the dose)

The side effects may be different if you are having asparaginase with other medicines.

Tell your doctor or nurse straight away if any of the side effects get severe.


Common side effects

More than 10 in every 100 people have one or more of these.

  • Tiredness and weakness (fatigue) during and after treatment – most people find their energy levels are back to normal within 6 months to a year
  • An allergic reaction during treatment – you have a test dose beforehand to check for this. The reaction is usually mild, causing an itchy rash. But it can sometimes be severe with difficulty breathing and a sudden drop in blood pressure, making you feel faint. Tell your nurse straight away if you have these symptoms
  • An increased risk of getting blood clots (thrombosis) – let your doctor or nurse know straight away if you have a sore, red, swollen area on your leg. Also tell them if you have sudden breathlessness, coughing or chest pain
  • High temperatures (fever) and chills
  • Bruising more easily due to a drop in platelets happens to 5 out of 10 patients (50%) – 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 (known as petechiae). Tell your doctor or nurse if you have any of these effects and don't take aspirin – it can increase the risk of bleeding

Occasional side effects

Between 1 and 10 in every 100 people have one or more of these.

  • Inflammation of the pancreas (pancreatitis) causing pain in the centre of your abdomen and sickness – this usually gets better on its own after treatment ends. You should not have asparaginase if you have had pancreatitis in the past. Tell your doctor if you have any of these symptoms
  • A change in mood or extreme sleepiness – this may happen from the first day of treatment but should stop when you finish treatment
  • Asparaginase can very rarely be toxic to your nervous system and cause a loss of energy, agitation, fits (seizures) or hallucination – tell your doctor or nurse if you have any of these symptoms
  • Feeling or being sick is usually mild and well controlled with anti sickness medicines
  • Loss of appetite and weight loss
  • Loss of fertility – we don’t know exactly how this drug affects fertility so do talk with your doctor before starting treatment if you plan to have a baby in the future
  • Liver changes that are very mild and unlikely to cause symptoms – the liver will almost certainly go back to normal when treatment is finished, but you will have regular blood tests to check how well your liver is working
  • Headaches, dizziness or confusion
  • Skin rashes and redness may occur – some people also have a swollen face and lips
  • Diarrhoea – you need to drink plenty of fluids. If the diarrhoea becomes severe or continues you could get dehydrated so tell your doctor or nurse
  • Swelling of the arms or legs
  • Difficulty swallowing – let your doctor or nurse know straight away if you have this
  • Muscle or joint pain
  • Fits (seizures)
  • Pale skin
  • Pain, redness, bruising and swelling of the injection site

Rare side effects

With this drug, fewer than 1 in 100 people have the following effects

  • An increased risk of getting an infection from a drop in white blood cells – it is harder to fight infections and you can become very ill. You may have headaches, aching muscles, a cough, a sore throat, pain passing urine, or you may feel cold and shivery. If you have a severe infection this can be life threatening. Contact your treatment centre straight away if you have any of these effects or if your temperature goes above 38°C
  • Tiredness and breathlessness due to a drop in red blood cells (anaemia) – you may need a blood transfusion
  • A rise in blood sugar – this can make you feel thirsty, hungry or pass a lot more urine than usual. Tell your nurse or doctor if you have these symptoms or before you have asparaginase if you are diabetic
  • A runny nose
  • Difficulty speaking due to a swollen voice box

Important points to remember

Talk to your doctor, pharmacist or nurse about all your side effects so they can help you manage them. They can give you advice or reassure you. Your nurse will give you a contact number to ring if you have any questions or problems. If in doubt, call them.

Other medicines

Tell your doctor about any other medicines you are taking, including vitamins, herbal supplements and over the counter remedies. Some drugs can react together.

Pregnancy and contraception

This drug may harm a baby developing in the womb. It is important not to become pregnant or father a child while you are having treatment and for a few months afterwards. Talk to your doctor or nurse about effective contraception before starting treatment.


Don't breastfeed during this treatment because the drug may come through in the breast milk.

Glucose and asparaginase

Asparaginase contains some glucose. Let your doctor know if you are diabetic. You may need to monitor your glucose levels more often.


Immunisations and chemotherapy

You should not have immunisations with live vaccines while you are having chemotherapy or for at least 6 months afterwards. In the UK, these include rubella, mumps, measles (usually given together as MMR), BCG, yellow fever and Zostavax (shingles vaccine).

You can have other vaccines, but they may not give you as much protection as usual until your immune system has fully recovered from your chemotherapy. It is safe to have the flu vaccine.

It is safe for you to be in contact with other people who've had live vaccines as injections. There can be problems with vaccines you take by mouth (oral vaccines), but not many people in the UK have these now. So there is usually no problem in being with any baby or child who has recently had any vaccination in the UK. You might need to make sure that you aren't in contact with anyone who has had oral polio, cholera or typhoid vaccination recently, particularly if you live abroad.


More information about asparaginase

This page does not list all the very rare side effects of this treatment that are very unlikely to affect you. For further information look at the Electronic Medicines Compendium website at

If you have a side effect not mentioned here that you think may be due to this treatment you can report it to the Medicines Health and Regulatory Authority (MHRA) at

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Updated: 14 October 2015