What are allergies? Symptoms, causes, tests, and treatments for allergic reactions
What are allergies?
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
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
- Runny nose
- Itchy eyes
- Skin rashes and hives
- Stomach cramps
- Trouble breathing
Common causes of allergies
- Occupational allergens
Gallery: Common triggers to allergic reactions
Animal dander is receiving clinical attention as major allergen source. Cats, dogs, birds, rodents, and any animal with fur or feathers produce animal dander.
How are allergies diagnosed?
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 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 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
Ask your doctor about a simple blood test for allergy.
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.
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.
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Pawankar R, Canonica GW, Holgate ST, Lockey RF. White book on allergy 2011-2012 executive summary. World Health Organization; 2013.
Asher MI, Montefort S, Björkstén B, Lai CK, Strachan DP, Weiland SK, Williams H, ISAAC Phase Three Study Group Worldwide time trends in the prevalence of symptoms of asthma, allergic rhinoconjunctivitis, and eczema in Triggers Testing Treatment Download this infographic (pdf) ALLERGY PATIENT WEBPAGE Unrestricted childhood: ISAAC phases one and three repeat multicountry cross-sectional surveys. Lancet. 2006;368(9537):733–743. doi: 10.1016/S0140-6736(06)69283-0.
Björkstén B, Clayton T, Ellwood P, Stewart A, Strachan D, ISAAC Phase III Study Group Worldwide time trends for symptoms of rhinitis and conjunctivitis: phase III of the inter-national study of asthma and allergies in childhood. Pediatr Allergy Immunol. 2008;19(2):110–124. doi: 10.1111/j.1399-3038.2007.00601.x.
Prescott SL, Pawankar R, Allen KJ, Campbell DE, Sinn JK, Fiocchi A, Ebisawa M, Sampson HA, Beyer K, Lee BW. A global survey of changing patterns of food allergy burden in children. World Allergy Organ J. 2013;6(1):21. doi: 10.1186/1939-4551-6-21.
Robert G. Hamilton, Kim Mudd, Mirinda Anderson White, Robert A. Wood, MD. Extension of food allergen specific IgE ranges from the ImmunoCAP to the IMMULITE systems. Ann Allergy Asthma Immunol. 2011;107:139 –144.
Ludman, S. W., & Boyle, R. J. (2015). Stinging Insect Allergy: Current Perspectives on Venom Immunotherapy. Journal of Asthma and Allergy, 8, 75–86. https://doi.org/10.2147/JAA.S62288
Asthma and Allergy Foundation of America. Available from: https://www.aafa.org/insect-allergy/#:~:text=Non%2Dstinging%20and%20non%2Dbiting,see%20with%20the%20naked%20eye
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