Anaphylaxis is a severe type of allergic reaction.
It can happen after exposure to triggers, such as:
Anaphylaxis can develop quickly and can be fatal. It should be treated as a medical emergency.
If anaphylaxis progresses, it can lead to a dangerous drop in blood pressure. This is known as 'anaphylactic shock'.
Anaphylaxis symptoms can vary, but often affect breathing, the throat and other body functions. Symptoms of anaphylaxis can include any of the following:
Sometimes, mild to moderate symptoms may happen before anaphylaxis. Symptoms may include:
Watch this video from Allergy & Anaphylaxis Australia (Opens in new tab) to learn how to recognise signs and symptoms of an allergic reaction.
Watch this video from Allergy & Anaphylaxis Australia (Opens in new tab) to see how to position a child or an adult having a severe allergic reaction.
If the person is unresponsive and not breathing normally, start CPR.
If you are not sure — always use the adrenaline autoinjector. It is better to use it than delay treating a serious reaction. Adrenaline does not have serious side effects if given unnecessarily, but can be lifesaving. If the person also has asthma, give the adrenaline autoinjector first. Then give the asthma reliever puffer.
Anaphylaxis is triggered by the immune system when it recognises a harmless substance as 'dangerous' (allergen).
The symptoms of an allergic reaction vary from person to person. They also depend on the type of allergen and how it entered the body. It may enter the body for example through ingestion, skin contact or inhalation.
This immune response can affect many different body systems, such as your:
Anaphylaxis is diagnosed by looking at your symptoms and checking your medical history. Your doctor may also examine you to confirm the diagnosis.
Anyone who has had or may have had anaphylaxis should ask their GP for a referral to an allergy specialist. This specialist can:
Anaphylaxis requires immediate treatment with adrenaline. Treatment involves quick, supportive care and positioning. You should lie flat to help blood flow and avoid walking or standing until you are stable.
In hospital, you may also receive oxygen and fluids through a vein if needed. After treatment, you will be checked for at least 4 hours. This is to check for any return of symptoms or complications.
Follow the steps on your anaphylaxis action plan (Opens in new tab). Be aware of your position and use your adrenaline injector as directed.
It is important to act quickly to help reduce your chance of complications. Untreated, anaphylaxis can quickly lead to:
People with diagnosed allergies should avoid all triggers and confirmed allergens.
If you have an allergy, you should always carry:
It's a good idea to ensure your friends and family know how to follow your anaphylaxis action plan in case you need help. Wearing a medical ID bracelet or necklace can also help others recognise and respond to the emergency.
You can also call the healthdirect helpline on 1800 022 222 (known as NURSE-ON-CALL in Victoria). A registered nurse is available 24 hours a day, 7 days a week.
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Last reviewed: November 2024
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