Allergic Reactions



Anaphylaxis is a severe allergic response. It can be life threatening.

It is important to seek emergency medical care right away if you have symptoms.


Some people become very sensitive to certain allergens or triggers. When they come in contact with it the immune system has a severe overreaction. This leads to the symptoms of anaphylaxis. Common triggers include:

  • Foods and food additives, especially eggs, peanuts, seafood, cow's milk, soy, fish, shellfish, seeds, and tree nuts
  • Insect stings or bites from bees, wasps, hornets, yellow jackets, and fire ants
  • Medications such as antibiotics (especially penicillin), medications used in anesthesia, seizure medications, and muscle relaxants
  • Vaccines
  • Latex products such as gloves, medical tubing, and condoms
  • Blood transfusions
Allergic Reaction to Medication (Hives)
Hives Medication
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Risk Factors

Factors that may increase your risk of anaphylaxis include:

  • Previous anaphylaxis
  • Family or personal history of eczema, hay fever, or asthma
  • Exposure to allergen
  • Repeat exposure to latex, may be found in:
    • Healthcare workers or other workers who use latex gloves
    • People with a lot of exposure to latex gloves or devices from medical care
    • Children with spina bifida



Symptoms often occur within minutes after contact with an allergen. Some may not show until hours later. They may be mild or severe enough to cause death. Symptoms may include:

  • Hives and itching
  • Warmth or redness of skin
  • Swelling, redness, stinging or burning, especially on the face, mouth, eyes, or hands
  • Light-headedness
  • Pale skin or sometimes blue skin color
  • Chest tightness, shortness of breath, difficulty breathing, and wheezing
  • Nausea, vomiting, cramping, diarrhea, or abdominal pain
  • Loss of consciousness


The doctor will ask about your symptoms and medical history. A physical exam will be done. All of this information will be used to reach a diagnosis.



Anaphylaxis will need immediate medical treatment, including:

  • Epinephrine (adrenaline) injection to help:
    • Open airways
    • Narrow blood vessels
    • Stop itching and hives
    • Relieve cramps in stomach
  • Corticosteroids or antihistamines—to decrease inflammation and improve breathing
  • Bronchodilators—to open airways
  • IV fluids—to help blood pressure.
  • Oxygen

Severe anaphylaxis may require:

  • Cardiopulmonary resuscitation (CPR)—if there is cardiovascular collapse
  • Mechanical ventilation—to help keep upper airway open

Future Incidents

Once you have had a reaction you have a higher risk of having another. Your doctor may give you a tool that allows you to easily inject epinephrine. It will slow or stop reaction from an allergen. You can keep it with you at all times. Be sure family and friends know how to use the tool too. Make sure the epinephrine has not expired.

Make sure the school nurse and teachers know about any allergies your child has. If your child has self-injectable epinephrine, make sure school staff knows how to use it and understand when it is needed.

Note: If you use your tool, you should go to the emergency room right away. Your symptoms can come back quickly even if they appear to have gone away.


Work with your doctor to find what caused your reaction. You may be referred to an Allergist for testing.

Once you know the cause, you can take steps to avoid contact with it. Avoiding triggers is the best prevention. Additional steps include:

  • Ask your doctor about allergy shots. They can decrease the risk of anaphylaxis. They may also make reactions less severe.
  • Wear a medical alert bracelet at all times. This will alert others to your allergies when you are unable to do so.
  • Let your doctor or dentist know about your allergies.
    • Ask that medications be taken as a pill. Injected medicine can cause a more severe reaction.
    • Wait in the care office for at least 30 minutes after you have an injection. Let the doctor know if you have any symptoms right away.
  • If you are allergic to insect stings, wear protective clothing when outside.
  • Exercise can trigger anaphylaxis for some. It may be associated with exercise alone or exercising after you eat a certain food. Avoid activity or combination of food and exercise that cause reactions.
    • It is also important to stop any exercise at the first sign of a reaction.

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.

Edits to original content made by Denver Health.

a (Anaphylactic Reaction; Severe Allergic Reaction)


American Academy of Allergy, Asthma & Immunology 

FARE—Food Allergy Research & Education 


Allergy Asthma Information Association 

Food Allergy Canada 


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Arnold JJ, Willimas PM. Anaphylaxis: recognition and management. Am Fam Physician. 2011;84(10):1111-1118.

Sampson HA, Munoz-Furlong A, et al. Second symposium on the definition and management of anaphylaxis: summary report—Second National Institute of Allergy and Infectious Disease/Food Allergy and Anaphylaxis Network symposium. J Allergy Clin Immunol. 2006;117(2):391-397.

Simons E. Anaphylaxis. J Allergy Clin Immunol. 2010;125(2 Suppl 2): S161-S181.