What is an adverse drug reaction?

Adverse reactions to drugs are common. Most are predictable and are known as side effects of the drug. Examples include diarrhoea caused by antibiotics and drowsiness caused by some antihistamines.

What is drug allergy?

Drug allergies are much less common children than in adults. It is not unusual for children to develop rashes with viral infections. These rashes can easily be confused with allergy to the medicine given when the child is unwell. This is often the case with antibiotics and painkillers.

Reactions often include a rash, which can come on suddenly or gradually. They may occur after the first dose or many doses of the medicine. Drug allergies are generally mild but can also be severe including anaphylaxis.

What will the doctor need to know about the reaction?

It is important for the doctor to know the name of the medicine suspected to cause a reaction, and any other medicines that were given at the time.

The doctor will also need to know:

  • why the drug was given
  • what symptoms developed
  • how quickly the symptoms developed
  • had the medicine been taken before, or since the event

Pictures or videos of the reaction can be very helpful. If possible, bring the medicine or drug packaging with you.

How is drug allergy diagnosed?

Allergy tests may be unreliable. Taking a dose of the drug in hospital is the most accurate way of telling if the reaction was caused by the drug. This is called a drug challenge and should be done when your child is well.

Sometimes, your doctor may advise your child just avoid the medicine in the future, for instance after severe blistering of the mouth or skin.

How is drug allergy managed?

For most children presenting with a possible drug allergy, a drug challenge rules out the allergy and there is no need to avoid the treatment in future.

If a drug allergy is confirmed, avoidance of the drug is usually advised. Your hospital doctor will inform your GP. It is important that you know which drug your child is allergic to. You must tell all health professionals about this allergy, including your dentist.

You should be careful when buying over the counter medicines, receiving medicines from overseas, from friends and family or over the internet.

Allergy alert jewellery is worn by some patients with drug allergy to inform doctors and other health professionals.

What if my child gets ill and needs the drug?

In most cases, there are alternative drugs that can be used. If there is no alternative, then your allergist may consider desensitising your child to the drug so that it can be tolerated.

What should you do if you think your child is having a reaction to a medicine?

Stop giving the drug to your child and tell your doctor.

For rashes and swelling, take a picture and give an antihistamine.

If there are severe symptoms:

  • difficulty breathing (wheezing, noisy breathing, blue colour)
  • swelling in the throat (noisy breathing, drooling)
  • feeling faint or dizzy, looking very pale (lie the child down with their legs raised).

Get help straight away and dial 999 stating “anaphylaxis” (ana-fil-ak-sis).

Where can I find more information on drug allergies?