Allergen-rich environment

What are allergies? Symptoms, causes, tests, and treatments for allergic reactions

What are allergies?

Cell diagram

When IgE antibodies react with an allergen such as pollen, cells will release chemicals that cause specific allergic symptoms, such as sneezing.

An allergy is an abnormal reaction of the immune system to normally harmless substances – known as allergens – present in the environment.

Depending on the allergy, reactions occur seasonally or throughout the year. If you are allergic, you produce too much IgE antibody in response to an allergen. When IgE antibodies react with an allergen, your body releases chemicals that cause specific allergic symptoms.

Allergies are common and affect people of all ages, genders, and ethnicities.

Allergies and related diseases including asthma, rhinosinusitis, atopic dermatitis, and life-threatening allergies to food, drug, and stinging insects affect at least 30% of the population and nearly 80% of families.1-4

The prevalence of allergic diseases has continued to increase in the industrialized world for more than 50 years.1

Worldwide, sensitization rates to one or more common allergens among school children are approaching 40–50%.1

Children and allergies

Children are particularly at risk as most allergies are inherited. But you do not have to be born with an allergy to be allergic. You can suddenly become allergic to something that has never been a problem before.

Typically, food allergies evolve into inhalant allergies, and clinical symptoms usually correlate to age, with eczema being found in infancy, followed by gastrointestinal distress in infancy or childhood. Rhinitis is commonly seen in later childhood, and respiratory symptoms are manifested by allergic asthma in the preteen and teenage years.5

Symptoms of allergies

Allergic symptoms

Allergy can cause a range of symptoms from mild to life-threatening. Mild allergic reactions often begin with a localized response in a specific area of the body, but more moderate and severe reactions can cause the symptoms to spread, even throughout the whole body. Anaphylaxis is a severe and potentially life-threatening allergic reaction that requires immediate treatment, usually with epinephrine.

Symptoms of allergies

  • Coughing
  • Runny nose
  • Itchy eyes
  • Sneezing
  • Skin rashes and hives
  • Eczema
  • Stomach cramps
  • Vomiting
  • Diarrhea
  • Swelling
  • Trouble breathing
  • Shock

Common causes of allergies

  • Animals
  • Drugs
  • Dust
  • Foods
  • Insects
  • Molds
  • Occupational allergens
  • Pollen

How are allergies diagnosed?

Allergy tests

Early and accurate diagnosis and treatment for allergies can help you live better.

Allergy tests can help you know for sure and diagnose which allergens are triggers. To diagnose, your doctor will take the medical history, perform a physical exam, and conduct a skin prick test or blood test.

If you or your child have allergy symptoms, talk to your doctor about taking a simple allergy blood test.

Skin prick test

Skin prick tests

Skin prick tests induce an allergic reaction by injecting the allergens under the skin. These induced allergic reactions:

  • May be long-lasting and uncomfortable
  • Pose the risk of severe reactions
  • Is used as a confirmatory test
  • Are not recommended for patients with certain skin conditions
  • Are not recommended for patients with a reduced histamine response
Blood test

Blood tests

Blood tests detect and measure the amount of allergen-specific antibodies in your blood. Blood tests:

  • Are simple as they involve only one needle prick
  • Ensure no risk of reaction
  • Are not affected by medications so there is no need to stop taking medications before the test
  • Are a convenient method for monitoring decreases in sensitization resulting from a medical intervention such as allergen avoidance
  • Are a valuable diagnostic tool for following development and prognosis of sensitization in childhood
  • Are readily available to primary care physicians
  • Are convenient for patients suffering from eczema, atopic dermatitis, and other skin conditions
  • Are practical and convenient method for infants and children, especially when affected by dermatographism

Treatments for allergies

Eliminate the causes of allergy in your personal environment

Allergies cannot be cured, but they can be managed. Sometimes the best way to manage an allergy is simply to remove the cause. Depending on your allergy, you may need to:

  • Control house dust with filters
  • Avoid allergy-causing foods
  • Limit outdoor activities during heavy pollen periods
  • Minimize exposure to certain animals

Use prescribed medication

Effective prescription drugs can reduce your allergy symptoms with few side effects. Always consult your doctor before taking any medication.

Receive immunotherapy

Immunotherapy can reduce sensitivity to pollens, dust, mold, spores, animal dander, and insects. This treatment enables a patient to build tolerance to a variety of allergens through regular allergen injections by a physician.

Read along as Thomas's zebra helps him understand his allergies.

Talking to your child about allergy testing? 

Calm fears and help them to understand their diagnosis with this fun, fact-filled audiobook.