Allergic and anaphylactic reactions

  • Allergic reactions are common in children. They happen when the immune system reacts to something in the environment that is normally harmless, such as food proteins, pollens or dust mites. Allergic reactions can be triggered by an allergen (the substance the person is allergic to) coming into contact with the skin, eyes, nose, lungs, stomach or bowel.

    The most common causes of food allergy in children are egg, peanut, tree nuts, cow's milk, soy, wheat, fish, shellfish and sesame. Other causes are bee or other insect bites (e.g. wasp or jack jumper ant), some medications (e.g. antibiotics or anesthetics) and latex (rubber).

    Many allergic reactions are mild, but some can be extremely severe. Anaphylaxis is the most severe form of an allergic reaction and is life threatening. It is estimated that one in every 100 school-age children have anaphylaxis. With planning and training, anaphylaxis can be treated effectively.

    Signs and symptoms of allergic reactions

    Mild to moderate allergic reaction

    An allergic reaction will include one or more of these symptoms, and it is possible that a number of them will happen at the same time:

    • hives, welts or wheals (a red, lumpy rash, like mosquito bites)
    • a tingling feeling in or around the mouth
    • stomach pain, vomiting* and/or diarrhoea (loose or runny poo)
    • facial swelling.

    The first time your child has any allergic reaction, take them to the GP. The doctor will confirm whether your child had an allergic reaction and advise you how to treat the reaction next time it happens. You may be referred to an allergy specialist. Be aware that occasionally a more severe reaction may occur when your child is exposed to the allergen for the second time.

    Severe allergic reaction (anaphylaxis)

    A severe allergic reaction involves a person's breathing and/or circulation (heart and blood pressure). At least one of the following symptoms indicates your child is having an anaphylactic reaction. The above symptoms of a mild to moderate reaction may or may not be present:

    • difficulty with breathing and/or noisy breathing
    • wheeze or persistent cough
    • swelling of the tongue
    • swelling and/or tightness in the throat
    • difficulty talking or hoarse voice
    • persistent dizziness or collapse
    • becoming pale and floppy (infants/young children)
    • *stomach pain and vomiting alone are signs of anaphylaxis after an insect stings.

    Call an ambulance immediately if your child has symptoms of anaphylaxis.

    First, use your child’s adrenaline autoinjector if it is available.

    Is my child's food reaction an allergy or intolerance?

    Sometimes a food intolerance can be confused with a food allergy because many of the symptoms are similar. However, intolerance and allergy are not the same thing – allergy involves the immune system but intolerance does not. Food intolerance will not lead to anaphylaxis.

    An allergic reaction to food can be triggered by even very small amounts. Intolerance is when a person can tolerate a certain amount of the food trigger, but when they have had too much, they become unwell (e.g. with diarrhoea, bloating, headaches, rash and mouth ulcers). One example of an intolerance is lactose intolerance.

    Treatment for allergic reactions

    Mild to moderate allergic reaction

    Most mild to moderate episodes of food allergy will respond well to an oral antihistamine medication. If your child has a known allergy, you should carry an antihistamine medicine with you at all times. Talk to your pharmacist or GP. Antihistamines that don’t cause drowsiness are recommended.

    Anaphylactic reaction

    The first-line treatment for anaphylaxis is adrenaline, which may be given as an injection. Your doctor will also prepare an Anaphylaxis Action Plan for your child. If your child has an anaphylactic reaction, follow the plan or do the following:

    • Have your child lie down, but if breathing is difficult allow them to sit.
    • Inject your child with the autoinjector, and call an ambulance immediately.
    • A second autoinjector is sometimes needed while waiting for an ambulance.

    If there is no autoinjector available, call an ambulance immediately. 

    An allergist will work with your child to find out what they are allergic to. Your child could also wear a medical alert pendant or bracelet to let other people know what may cause them to have an allergic reaction. Talk to your doctor about this.


    If your child has a history of anaphylaxis, an adrenaline autoinjector will be prescribed for use in any future episodes. The most common autoinjectors in Australia are EpiPen/EpiPen Jr and Anapen/Anapen Jr.

    You and your child (if they are old enough) will need to learn how to use the autoinjector. Keep a copy of your child's Anaphylaxis Action Plan with the autoinjector. Make sure the autoinjector is stored:

    • in an insulated container clearly labelled with your child's name
    • at room temperature
    • in a safe, easily accessible central location.

    When out of the house, your child's autoinjector and action plan should be carried with them at all times.

    Regularly check the expiry date and ensure the window is clear on the autoinjector.

    Using an autoinjector in hospital

    If your child is in hospital, you should bring their adrenaline autoinjector and let staff know that you have it with you. They will let you know where to store it so you can access it quickly and easily. Staff will go through a checklist with you to confirm you know how and when to use your child’s autoinjector during your child’s hospital stay.

    If your child experiences any symptoms of anaphylaxis while in hospital: 

    • lie your child down
    • immediately press the buzzer in your child’s room to alert a staff member, and call out for attention if you can
    • inject your child with their autoinjector but do not discard it 
    • tell staff you have given your child their autoinjector.

    Staff will call for immediate assistance to provide further assessment and treatment if needed.

    When you leave the hospital, remember to take your child’s adrenaline autoinjector home with you. If you have used your child’s adrenaline autoinjector in hospital, make sure staff provide you with a prescription for a replacement before you go home.

    Your team of doctors in the hospital will suggest the next appropriate steps in your management

    Preventing allergic and anaphylactic reactions

    An important aspect of allergy and anaphylaxis management is prevention by avoiding the trigger.

    If your child is allergic to food, teach them not to share or swap food with others, and to always wash their hands before eating. Teach your child to be very careful when eating take-away food or eating at restaurants and cafes. For parties and play dates, always notify the host of your child's allergies and ensure they have access to your child's autoinjector and know how to use it. Consider providing separate food for your child.

    Schools, kindergartens and childcare centres will have policies in place to prevent reactions in children at risk of anaphylaxis, and staff will be trained in how to manage reactions if they occur. The policies will cover the following issues:

    • food sharing and treats
    • banning products 
    • food preparation and serving
    • art/craft
    • excursions and camps.

    Talk to your school or childcare centre about your child's allergies, and what allergy policies they have in place.

    Asthma and anaphylactic reactions

    For children with both asthma and anaphylaxis, it is very important to maintain good asthma symptom control. This will reduce the risk of severe breathing system involvement during an allergic reaction.

    Key points to remember

    • Allergic reactions are common in children. Most reactions are mild.
    • A severe allergic reaction (i.e. anaphylaxis) involves a person's breathing and/or circulation.
    • Anaphylaxis is the most severe form of an allergic reaction and is life threatening.
    • An important aspect of allergy and anaphylaxis management is prevention by avoiding the cause.
    • Treatment for anaphylaxis involves lying the child flat (or seated), giving an autoinjector and calling an ambulance.
    • If your child experiences symptoms of anaphylaxis while they are in hospital, immediately inject them with their autoinjector and tell a staff member.

    For more information

    Common questions our doctors are asked

    Will my child grow out of her allergies?

    Some children outgrow their allergies altogether. Children who are allergic to milk, egg, wheat and soy are more likely to outgrow their allergies than those allergic to peanuts, tree nuts, fish, shellfish and sesame.

    Should schools ban food products that children are allergic to?

    Banning of products that contain an allergen is not recommended. Banning will not succeed in creating an allergy-free zone. It is difficult to achieve a perfect ban for a variety of reasons, e.g. parents of non-allergic children may not comply with the ban, staff and students can become complacent. Instead, it is recommended that the people associated with the child with the allergy become aware of allergy-causing foods, and the child knows they must only eat their own food.

    Why do so many children have allergies and anaphylaxis now?

    Food allergy and anaphylaxis seem to have increased significantly in recent decades; however, the reason for this increase is not known. Researchers are investigating why more children have allergies these days, and they are looking into issues such as methods of food processing or the fact that babies are now exposed to fewer infections in early childhood. What is known is that allergies do tend to run in families.

    My child has had a mild allergic reaction to some foods. Should I buy an EpiPen just in case my child has an anaphylactic reaction one day?

    No. It is best to have your child assessed by an allergy specialist, to determine whether they have had anaphylaxis and what they are specifically allergic to. If the specialist believes your child has had anaphylaxis, or they are at greater risk of anaphylaxis, they will organise an EpiPen prescription for you.

    Developed by The Royal Children's Hospital Allergy and Immunology department. We acknowledge the input of RCH consumers and carers.

    Reviewed October 2021.

    Kids Health Info is supported by The Royal Children’s Hospital Foundation. To donate, visit


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