Drug challenge information

Drug challenges are tests that are performed in hospital to see if your child is allergic to or able to take a particular medicine. A drug challenge tests if your child is allergic to a particular drug or medicine. It is done under close medical supervision. 

If your child does not experience any allergic symptoms, you can be confident that they do not have an allergy to that medicine. 

This means they will be able to take the medication in the future, if needed.

What to do in an emergency 

Severe reactions to medicines are very rare if your child has tolerated the challenge dose in hospital.

If you are worried your child is having a severe reaction to the medicine, please call an ambulance (000) or present to your nearest Emergency Department without delay.

About the challenge

The child is given a very low dose of the medicine, followed by a second dose about 30 minutes later.

A drug challenge lasts about two hours. 

Possible risks

Your child may have an allergic reaction to the drug being tested. 

This is why the test must be done in hospital and not at home. We carefully monitor your child during the test and a doctor is always available if needed.

If your child experiences an allergic reaction, we will stop the test immediately.

Medicine(s) will be given to relieve any symptoms and to stop the reaction from getting worse – this may be an antihistamine such as cetirizine or, in the case of a more severe reaction, adrenaline. 

Allergic reactions during the challenge 

If your child is allergic to the medicine, they must avoid the medicine in the future. We will provide a letter with further information for you and your child’s GP. 

We will arrange appropriate follow- up in the allergy clinic, if needed. 

After the challenge

If no allergic reactions occurred, your child will be given a short course of the medicine to take at home. This is to check there are no delayed reactions to the medicine. 

Delayed reactions 

If you are concerned about a non-severe allergic reaction that your child has to the antibiotic, please email SCHN- Drugallergy@health.nsw.gov.au at any time and we will reply between Monday to Friday 9 am to 5 pm. 

If you are concerned after hours, you can call the hospital switchboard (9382 1111) to put you through to the immunologist on call. 

Last updated Monday 25th March 2024