Allergy and immunology

What are allergies? What is immunology?

Allergies such as hay fever, asthma, eczema, hives and food allergies are the body's reaction to allergens — foods, plants, animals, insect stings, pollens, moulds, chemicals and medicines.  Most immediate allergic reactions are caused by a reaction between a protein in the blood called immunoglobulin and the substance you are allergic to. Delayed reactions are caused by a process not involving immunoglobulin. Only immediate reactions cause anaphylaxis, an immediate life-threatening reaction that can result in breathing problems, low blood pressure and even unconsciousness. 

Most allergens are harmless for most people, but estimates suggest that about one person in four is allergic to something and roughly half of all allergy sufferers are children. Allergies to pollens, house dust mites and animals usually cause symptoms including a runny nose, blocked nose and itchy eyes. When caused by seasonal pollens, this is also called hayfever and can cause wheezing and coughing in people with asthma. Allergies to foods may cause skin problems such as hives or itchy skin, or bowel problems such as tummy ache, vomiting or diarrhoea. Sufferers may also develop problems with breathing, including tongue swelling, coughing and wheezing. 

Immunology is the branch of medicine that deals with our defence or immune systems. All humans are prey to infection or invasion from viruses, bacteria and parasites, which can lead to serious diseases. The immune system is the body's defence mechanism against harmful organisms and infection, and can provide some protection against serious diseases, like cancer.

How do we help children with allergies and immunology problems?

The Sydney Children’s Hospitals Network provides multidisciplinary clinical, diagnostic and educational services for allergic and immunological conditions. Patients range from those with general allergy conditions to those with chronic and complex rare diseases and patients with complex allergies.

Referral units operate from Sydney Children’s Hospital and The Children’s Hospital at Westmead. The Allergy Services diagnose and manage patients with multiple allergies, anaphylactic-type food allergies, drug allergies, stinging insect allergies and severe atopic disease. Clinical services provided to patients by the immunology service include diagnosis and management of patients with rare diseases requiring tertiary level care, such as primary immunodeficiency disorders, complex autoimmune diseases like systemic lupus erythematosis (SLE) and autoinflammatory disorders.

The Immunology Laboratory at The Children’s Hospital at Westmead provides diagnostic testing services in the areas of immune function, immunogenetics, and allergy.

Further information

Read more about allergy and immunology in our snapshot of children's allergies and immunological diseases. 

You can also read our allergy fact sheets - Allergy tests, Food allergies and eczema, Epipen use, Food allergies and anaphalaxis — information for schools, House dust mite allergy