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Patient Education

Our Health Library information does not replace the advice of a doctor. Please be advised that this information is made available to assist our patients to learn about general health issues that may not be related to Ear, Nose and Throat Disorders. Our providers may not see and/or treat all topics found herein

Allergic reaction

An allergic reaction is an overreaction of the immune system to a substance called an allergen. Allergens include chemicals, foods, medicines, mold, plants, and pollen.

Symptoms of an allergic reaction can range from mild and annoying to severe and life-threatening.

  • Allergens can affect different tissues in the body, such as the airways, eyes, gastrointestinal tract, nose, lungs, and skin.
  • Some allergic reactions, such as hives or itching around an insect bite or where a plant or chemical touched the skin, affect only one area of the body.
  • Other allergic reactions may affect the whole body, causing itching all over, swelling, fainting, belly pain, nausea, vomiting, or difficulty breathing.
  • A severe allergic reaction (called anaphylaxis) can lead to shock and even death.

Allergic reactions may not occur the first time a person is exposed to an allergen. A person may become more sensitive to the allergen with each exposure.