Asparaginase is a medicine which is given at the same time as chemotherapy drugs.

It is an enzyme which deprives leukaemia cells of essential nutrients so that they die.

How is asparaginase given?

It is usually given in one of two ways:

  • by injection into a muscle (intramuscularly or IM)
  • by injection into a vein (intravenously or IV) through a cannula, central venous catheter or implantable port

What are the side effects of asparaginase?


Asparaginase may cause an itchy rash.


This may occur after asparaginase is given but it does not usually last for long.

Temporary effect on liver function

Asparaginase can cause some mild changes to your child’s liver function. This will return to normal when the treatment is finished. Blood tests may be taken to monitor your child’s liver function.

Allergic reaction

Some people receiving asparaginase have an allergic reaction to the drug. This reaction may be mild to severe. Signs of a mild allergic reaction include skin rashes and itching, high temperature, shivering, redness of the face, a feeling of dizziness or headache. If you see any of these signs, please report them to a doctor or nurse. Signs of a severe allergic reaction include any of the above, as well as shortness of breath. If you are in hospital and your child shows signs of an allergic reaction, call a doctor or nurse immediately. If you are at home and your child shows signs of a severe allergic reaction, call an ambulance immediately.

Increased tendency for blood clotting within blood vessels

For two to three weeks after receiving asparaginase, there may be a slight increase risk for blood clot formation with blood vessels. This is not common, but it does occur in a small proportion of children. The risk of blood clot formation may be further increased if the child and/or close family members have had a previous history of easy blood clots, such as deep venous thrombosis (DVT) or pulmonary embolism (PE). It is important to let the doctors know of such past history before receiving asparaginase. The risk of blood clot formation may also be increased if the child has a central venous catheter. Therefore, in some children we delay the insertion of a central venous catheter until a few weeks after starting treatment.

If blood clots were to occur, your child will be given medicines to thin the blood and dissolve the clot.

Bleeding and bruising

With asparaginase your child’s blood may take more or less time to clot than normal. Therefore, there may be a slight chance of your child bruising or bleeding more easily than normal. This is less common than blood clot formation. Please report any bruising or bleeding to your child’s doctor.


For two to three weeks after receiving asparaginase, there may be a small chance of pancreatitis (inflammation of the pancreas gland). This side effect is uncommon. The pancreas is a gland behind the stomach which helps to digest food and regulate the body’s blood sugars. Inflammation of this gland can result in severe abdominal pain and severe nausea and vomiting. If this occurs, your child needs to be admitted to hospital for supportive treatment. The majority of children with pancreatitis recover without long term problems.

Important information about asparaginase

Your child must remain in the hospital or outpatient department for at least one hour after an injection of asparaginase to check for any allergic reaction.

Asparaginase and interactions with other medicines

Some medicines can react with asparaginase, altering how well it works. Always check with your doctor or pharmacist before giving your child any other medicine, including medicines on prescription from your family doctor (GP), medicines bought from a pharmacy (chemist) or any herbal or complementary medicines.

Compiled by: 
The Pharmacy department in collaboration with the Child and Family Information Group
Last review date: 
May 2013


Please read this information sheet from GOSH alongside the patient information leaflet (PIL) provided by the manufacturer. If you do not have a copy of the manufacturer’s patient information leaflet please talk to your pharmacist. A few products do not have a marketing authorisation (licence) as a medicine and therefore there is no PIL.

For children in particular, there may be conflicts of information between the manufacturer’s patient information leaflet (PIL) and guidance provided by GOSH and other healthcare providers. For example, some manufacturers may recommend, in the patient information leaflet, that a medicine is not given to children aged under 12 years. In most cases, this is because the manufacturer will recruit adults to clinical trials in the first instance and therefore the initial marketing authorisation (licence) only covers adults and older children.  

For new medicines, the manufacturer then has to recruit children and newborns into trials (unless the medicine is not going to be used in children and newborns) and subsequently amend the PIL with the approved information. Older medicines may have been used effectively for many years in children without problems but the manufacturer has not been required to collect data and amend the licence. This does not mean that it is unsafe for children and young people to be prescribed such a medicine ‘off-licence/off-label’. However, if you are concerned about any conflicts of information, please discuss with your doctor, nurse or pharmacist.