Anaphylaxis is the most severe form of an allergic reaction and can be life-threatening. Many different allergens and situations can cause anaphylaxis. An anaphylactic reaction can involve different parts of the body. Usually there will be a skin reaction, such as hives or swelling, plus a second organ system involved in the reaction, like the gastrointestinal tract, the cardiovascular system or the airway.
- Skin changes. The skin may show flushing and hives or swelling, or it may become itchy.
- Cardiovascular system signs. These signs may include rapid heart rate, low blood pressure, shock, arrhythmias (changes in heart rhythm) and loss of consciousness.
- Gastrointestinal system signs. These signs include distension (abnormal pressure and expansion of the abdomen), vomiting, diarrhea, nausea, pain or cramps.
- Respiratory system signs. These signs include swelling of the airway, wheezing and difficulty breathing. The tongue could swell and block the airway.
- Other symptoms. Other symptoms may include sweating, a sense of impending doom and a metallic taste in the mouth.
Common allergens that may cause anaphylaxis include:
Rarely, symptoms of anaphylaxis can occur without an allergen being involved or identified. This type of reaction is called an anaphylactoid reaction. Features of anaphylactoid reactions include:
- Use of nonsteroidal anti-inflammatory drugs (NSAIDs) like aspirin and ibuprofen
- Use of direct mast cell releasers like contrast media or chemotherapeutic agents
- Idiopathic cases (no cause is found)
More than 70 percent of children who have anaphylaxis will have respiratory system symptoms, and over 80 percent will have hives or swelling of the deep tissue of the skin, lips or tongue. Your child might experience an anaphylactic reaction in as little as a few seconds after being exposed to the allergen, or the reaction may build over a few hours. The more serious reactions tend to happen quickly. Reactions may come in two phases: an early phase and one that may be delayed for six hours. When the reaction occurs more than two hours after exposure, it tends to be less severe.
Some children may experience anaphylaxis after exercise. Their skin may itch with or without hives, and they may have low blood pressure and difficulty breathing. Eating food such as celery, wheat or shellfish a few hours before exercising may be a trigger for this rare problem.
Diagnosis of Anaphylaxis
Anaphylaxis occurs when your child’s immune system creates an antibody called immunoglobulin E (IgE). This antibody is associated in exaggerated immune responses—hypersensitivity or "classic" allergy. If there is an allergic reaction, the immune system’s interaction of the IgE antibody and the allergen causes the allergic symptoms.
Allergy testing, done with the skin prick test after a detailed medical history, can find the substances (allergens) that may have caused your child to make this antibody (IgE) and have this kind of a reaction.
Anaphylaxis is a medical emergency, and your child needs to be treated as soon as possible by taking these steps:
- Remove any potential allergens that may cause the reaction to get worse.
- Make sure your child receives epinephrine or adrenaline right away. Timing of treatment is crucial—the sooner treatment is started, the better the outcome.
- Once the epinephrine is given, you must take your child to the emergency department.
While Benadryl (diphenhydramine) can treat itching due to hives, it will not help treat a life-threatening reaction and should not be used as the only treatment for anaphylaxis. Do not use Benadryl to replace epinephrine. With a life-threatening allergic reaction, do not waste any time looking for diphenhydramine (Benadryl). Go with the epinephrine.
The best management for anaphylaxis is for your child to avoid the allergen. Allergy specialists at Riley at IU Health can help you identify the allergen and how to avoid it. An allergy specialist can also teach you how to give your child epinephrine, including when to use it and what to do once epinephrine is used. Children who experience anaphylaxis should wear a medical alert bracelet.
Your child's allergy specialist will help you with a food allergy emergency plan, both for home and for your child’s school or day care. The allergist has the experience and expertise to guide you through this serious condition. You may also want to consider joining a support group such as Food Allergy Research & Education (FARE) if food is a trigger for your child’s reaction.
Key Points to Remember
Key Points to Remember
- Anaphylaxis is the most severe form of an allergic reaction and can be life-threatening.
- Allergens like foods, medicines, insect stings or shots may cause anaphylaxis.
- Anaphylaxis usually involves multiple systems of the body—most often the skin and the gastrointestinal tract, cardiovascular system or airway.
- Anaphylaxis is an emergency. Once you give your child epinephrine, you must take him or her to the emergency room.
- Do not use Benadryl (diphenhydramine) to replace a shot of epinephrine.
Support Services & Resources
Support Services & Resources
Visit the trusted websites below to learn more about anaphylaxis.
Riley at IU Health offers a broad range of supportive services to make life better for families who choose us for their children's care.
The American Academy of Allergy, Asthma & Immunology provides in-depth information about anaphylaxis.
The American College of Allergy, Asthma & Immunology provides more information about anaphylaxis.
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