Symptoms and Signs of Allergic Reaction

Medical Author:
Medically Reviewed on 8/5/2022

Doctor's Notes on Allergic Reaction

An allergic reaction is an exaggerated response by the body's immune system to a substance in the environment. Allergies are caused by an inappropriate or misguided reaction to foreign substances. The substances that trigger allergic reactions are called allergens. There are many different kinds of allergens, including pollens, plants, eggs, nuts, foods, and animal dander.

Signs and symptoms of an allergic reaction include:

  • itching and watering of the eyes, 
  • nasal congestion, 
  • sneezing, 
  • runny nose, 
  • scratchy throat, and 
  • cough due to postnasal drip. 

Other associated symptoms may include:

Anaphylactic reactions are serious allergic reactions that can be life-threatening. In an anaphylactic reaction, swelling of the throat leads to difficulty breathing.

What Is the Treatment for Allergic Reaction?

Treatment for an allergic reaction depends on the symptoms and severity of the reaction. 

  • Antihistamine and decongestant medications may be useful for allergic reactions that involve nasal congestion or sneezing. 
  • Corticosteroids may be helpful in treating allergic skin rashes. 
  • Bronchodilator medications and steroids may be used for allergic asthma

For severe allergic reactions (anaphylaxis), treatment may consist of:

  • Epinephrine injections 
  • Oxygen administration
  • Medications to assist with breathing
  • Intravenous antihistamines and steroid medications

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Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.