Anaphylaxis: How to recognize and respond to a severe allergic reaction

Peanuts are a common allergen

What is anaphylaxis?

Anaphylaxis is a severe allergic reaction to certain substances called allergens. When an allergen enters the body of a child with an allergy, the child’s immune system treats it as an invader and overreacts. This reaction happens a few minutes to an hour after the child is exposed to an allergen and can be life threatening.

Common causes of anaphylaxis

Common allergens include drugs, such as penicillin, foods, such as peanuts, and insect bites or stings, such as bee stings.

An allergen can enter the body in different ways.

  • A child may inhale (breathe in) or eat an allergen. It is best to speak to your child’s allergist about the inhaled allergens that would be a problem for your child, as not all of these allergens will cause a reaction.
  • A child might receive an injection that contains an allergen.

When the body is exposed to an allergen, it releases chemicals called histamines. These and other chemicals released by the body cause the common signs and symptoms of anaphylaxis.

Signs and symptoms of anaphylaxis

The signs and symptoms of anaphylaxis may include:

  • abdominal (belly) pain, nausea, vomiting or sudden onset of diarrhea
  • difficulty breathing, throat constriction (tightening) or difficulty swallowing
  • coughing
  • fainting, lightheadedness or dizziness
  • hives, itching, redness of the skin
  • swollen eyes, lips or face
  • rapid or irregular heartbeats
  • slurred speech.

Complications of anaphylaxis

If left untreated, anaphylaxis may cause your child to have blocked airways, go into shock or have a heart attack (cardiac arrest).

What you can do for your child during anaphylaxis

Anaphylaxis is a medical emergency. If your child has anaphylaxis, see a doctor right away.

  • Call 911 or take your child to your nearest emergency department.
  • If your child has emergency allergy medication, such as epinephrine (EpiPen or Allerject), inject it right away.
  • Calm and reassure your child.
  • Check your child's airway and breathing. A hoarse or whispered voice and high-pitched breathing sounds are signs that your child's throat is swollen.
  • Do not give any medication by mouth if your child is having trouble breathing.

What your child's doctor can do for anaphylaxis

It is very important for a doctor to see your child right away, even if symptoms have not yet appeared or have come and gone. Symptoms can disappear and then return a few hours later.

Your child’s doctor may give your child an injection of epinephrine or steroid or other medicine. Your child may also receive antihistamines to reduce any skin symptoms of their allergic reaction.

If you take your child to the emergency department, a tube may be placed through their nose or mouth and into their airways to help them breathe. A child with anaphylaxis should stay in the hospital for observation after their first allergic reaction.

How to prevent shock in your child with anaphylaxis

  • Calm and reassure your child.
  • Lay your child flat on the floor or ground. Do not place a pillow under your child's head, as this makes it more difficult for them to breathe.
  • Use cushions or other supports to keep your child's feet raised above the level of their heart.
  • Cover your child with a blanket to keep them warm.

You may need to perform CPR (cardiopulmonary resuscitation) to assist or restore blood circulation. There are different instructions for CPR on a baby and CPR on a child.

How to prevent repeated episodes of anaphylaxis

The best way to prevent anaphylaxis is for your child to avoid any known allergens. Many people are not aware of an allergy until they are exposed to an allergen and have an anaphylactic reaction.

Following their first episode of anaphylaxis, your child should see an allergist. This is a doctor who specializes in diagnosing and treating allergies.

The doctor will diagnose the allergen responsible for your child’s anaphylaxis and may also prescribe an automated epinephrine injector such as EpiPen or Allerject. Your child should carry this injector with them at all times in case of emergency. Ideally, your child will carry one injector and a second will be readily available nearby.

Your child should also wear a Medic Alert or similar bracelet that indicates their allergies to others so that they can get help right away if they need it.

Key points

  • Anaphylaxis is a severe reaction to an allergen such as certain foods, medications and insect bites or stings.
  • Common symptoms of anaphylaxis include difficulty breathing, dizziness, hives, swollen eyes and rapid heartbeat. If left untreated, anaphylaxis can be life threatening.
  • If someone has anaphylaxis, call 911 or go to your nearest emergency department immediately.
  • If it is your child’s first episode of anaphylaxis, see an allergist for a full diagnosis. Your child may be prescribed an epinephrine injector, which they should carry with them at all times.
​Vy​ Kim, MD, FRCPC
Anna Kasprzak, RN