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.This page explains what asparaginase is, how it is given and some of the possible side effects. Each person reacts differently to medicines, so your child will not necessarily suffer from every side effect mentioned. If you have any questions or concerns, please speak to your doctor, nurse or pharmacist.Asparaginase is usually given in one of two ways which will be specified in your child’s treatment protocol:

  • 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?


Asparaginase may cause an itchy rash. Please tell your doctor or nurse if your child develops a rash. They will advise you on the appropriate treatment to use.

Fever or raised temperature

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 how well your child’s liver works. This will return to normal when the treatment is finished. Blood tests (LFTs) may be taken to monitor your child’s liver function.

Allergic reaction

Some people receiving asparaginase have an allergic reaction to the medicine. 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 a severe 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 increased risk of blood clot formation within blood vessels. This risk may be further increased if your child and/or close family members have had a previous history of blood clots, for instance, 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 may also be increased if the child has a central venous catheter. Therefore, in some children we delay the insertion of central venous catheter until a few weeks after starting treatment. If blood clots 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 pancreas). 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 nausea and vomiting. If this occurs, your child needs to be admitted to hospital for treatment. The majority of children with pancreatitis recover without long term problems.

Interactions with other medicines

Some medicines can interact 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.


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.

How to store asparaginase

If your community team are giving your child asparaginase at home, keep it in a refrigerator (2°C to 8°C). Ensure the medicine is brought to room temperature before giving it to your child.

Compiled by:
The Pharmacy department in collaboration with the Child and Family Information Group
Last review date:
September 2019