Authored by Revere Health

What are Allergies and How to Recognize a Reaction

July 5, 2017 | Allergy and Immunology

Allergic reactions can span a wide range of possible symptoms and outcomes, and they’re very common—as many as 30 percent of US adults and 40 percent of children have some kind of allergy.

Here are the basics of allergic reactions and how to recognize moderate or serious reactions.

Facts About Allergic Reactions

The immune system is designed to defend the body from things like bacteria and viruses, but it doesn’t always attack the right sources. Certain foods or pollens are examples of allergens, or items that can trigger the immune system to release antibodies. These antibodies tell cells to block that substance, which causes the cells to send out histamine—this causes blood vessels to expand, and histamine, with the help of other chemicals, trigger allergy symptoms.

Antibodies target only one type of allergen, which is why many people just have a single major allergy and not several. You can become in contact with allergens through the skin, eyes, nose, mouth or stomach. In many cases, first-time exposure to a substance may only produce a mild reaction, but repeated exposures may lead to more serious reactions.

Causes of Allergies

Family history can be important in the formation of allergies, and common allergens that cause allergies can include:


  • Animal dander
  • Bee stings
  • Certain medications, including penicillin
  • Dust mites
  • Foods: Especially peanuts, tree nuts, shellfish, fish, eggs, milk, wheat and soy
  • Insect bites
  • Latex or other touched materials
  • Mold
  • Plants and pollen


Symptoms and Recognizing Reactions

Symptoms of allergic reactions can range from mild to extreme or even life-threatening, all depending on how the body reacts and how much of the allergen is in your system. Symptoms generally depend on the type of allergen or reaction:

  • Hay fever: Also called allergic rhinitis, hay fever can cause sneezing, runny nose, allergic conjunctivitis (red, swollen and watery eyes), or itchiness in the eyes, nose or the roof of the mouth.
  • Food allergies: Allergic reactions to food may cause a tingling in the mouth, or swelling in the tongue, lips, throat or face. They can also lead to hives, and in the worst cases can lead to anaphylaxis.
  • Eczema: Also called atopic dermatitis, this is a skin condition that causes itching, redness, peeling or flaking.
  • Medications: Allergies to a certain drug may cause a rash, facial swelling, hives, wheezing or anaphylaxis.
  • Stings: Bee stings or other insect stings may cause symptoms such as large swelling (edema), itching or hives all over the body, shortness of breath, wheezing, chest tightness or a cough. Anaphylaxis is also possible.

Serious Reactions

Severe cases of allergic reactions can lead to anaphylaxis, a serious situation that puts the body into shock and leads to life-threatening complications. The most likely causes of anaphylaxis are food, medications, insect bites or contact with latex. In some cases, a second anaphylactic episode will take place up to 12 hours after the first.

Symptoms of anaphylaxis may include:

  • Trouble breathing
  • Tightness in the throat
  • Hives or swelling
  • Nausea or vomiting
  • Faintness or dizziness
  • Rapid pulse or stopped heartbeat

If you have a history or high risk of anaphylaxis, your doctor might prescribe medicine you can give yourself, or be given by someone else. These are devices called epipens that you carry with you at all times in cases of a serious reaction. Even if you’ve used this device, always call 911 and go right to the emergency room after an anaphylactic reaction.

If you’re dealing with allergic reactions ranging from mild to severe, your doctor can provide recommendations for proper safety and symptom reduction.

Our Utah Valley allergy specialists are able to diagnose and treat patients who suffer from allergic and immunologic disorders. Our board-certified physicians have over 30 years of combined experience working with pediatric and adult patients with a variety of medical problems using the most comprehensive and up-to-date medical therapies.



“What Is an Allergic Reaction?” WebMD.

“Allergic reactions.” MedlinePlus.


The Live Better Team

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This information is not intended to replace the advice of a medical professional. You should always consult your doctor before making decisions about your health.