Editing Allergy (section)

{{short description|Immune system response to a substance that most people tolerate well}}
{{For-multi|the journal|Allergy (journal)|the (G)I-dle song|Allergy (song)}}
{{Use American English|date=March 2023}}
{{Use dmy dates|date=March 2023}}
{{Infobox medical condition (new)
| name            = Allergy
| synonyms        =
| image           = Hives2010.JPG
| caption         = [[Hives]] are a common allergic symptom.
| field           = [[Immunology]]
| symptoms        = [[allergic conjunctivitis|Red eyes]], itchy rash, vomiting, [[rhinorrhea|runny nose]], [[shortness of breath]], swelling, [[sneezing]], and cough
| complications   =
| onset           =
| duration        =
| types           = [[Allergic rhinitis|Hay fever]], [[Food allergy|food allergies]], [[atopic dermatitis]], [[allergic asthma]], [[anaphylaxis]]<ref name=NIH2015Types/>
| causes          = [[Genetics|Genetic]] and environmental factors<ref name=Kay2000/>
| risks           =
| diagnosis       = Based on symptoms, [[skin prick test]], [[blood test]]<ref name=NIH2012pdf/>
| differential    = [[Food intolerances]], [[food poisoning]]<ref name=Bah2012/>
| prevention      = Early exposure to potential allergens<ref name=Sic2014/>
| treatment       = Avoiding known allergens, medications, [[allergen immunotherapy]]<ref name=NIH2015Imm/>
| medication      = [[Corticosteroid|Steroids]], [[Histamine antagonist|antihistamines]], [[epinephrine (medication)|epinephrine]], [[mast cell stabilizer]]s, [[antileukotriene]]s<ref name=NIH2015Imm/><ref name=Review09/><ref>{{cite journal | vauthors = Finn DF, Walsh JJ | title = Twenty-first century mast cell stabilizers | journal = British Journal of Pharmacology | volume = 170 | issue = 1 | pages = 23–37 | date = September 2013 | pmid = 23441583 | pmc = 3764846 | doi = 10.1111/bph.12138 }}</ref><ref>{{cite journal | vauthors = May JR, Dolen WK | title = Management of Allergic Rhinitis: A Review for the Community Pharmacist | journal = Clinical Therapeutics | volume = 39 | issue = 12 | pages = 2410–2419 | date = December 2017 | pmid = 29079387 | doi = 10.1016/j.clinthera.2017.10.006 | doi-access = free }}</ref>
| prognosis       =
| frequency       = Common<ref name=NIH2015Epi/>
| deaths          =
}}

<!-- Definition and symptoms -->
'''Allergies''', also known as '''allergic diseases''', are various conditions caused by [[hypersensitivity]] of the [[immune system]] to typically harmless substances in the environment.<ref name=Con2007>{{cite book| vauthors = McConnell TH |title=The Nature of Disease: Pathology for the Health Professions|date=2007|publisher=Lippincott Williams & Wilkins|location=Baltimore, MD|isbn=978-0-7817-5317-3|page=159|url=https://books.google.com/books?id=chs_lilPFLwC&pg=PA159}}</ref> These diseases include [[Allergic rhinitis|hay fever]], [[Food allergy|food allergies]], [[atopic dermatitis]], [[allergic asthma]], and [[anaphylaxis]].<ref name=NIH2015Types>{{cite web|title=Types of Allergic Diseases |url=https://www.niaid.nih.gov/topics/allergicdiseases/Pages/allergic-diseases-types.aspx |website=NIAID |access-date=17 June 2015 |date=29 May 2015 |archive-url=https://web.archive.org/web/20150617123632/http://www.niaid.nih.gov/topics/allergicdiseases/Pages/allergic-diseases-types.aspx |archive-date=17 June 2015 }}</ref> Symptoms may include [[allergic conjunctivitis|red eyes]], an itchy [[rash]], [[sneeze|sneezing]], [[coughing]], a [[rhinorrhea|runny nose]], [[shortness of breath]], or swelling.<ref name=NIH2015Sym>{{cite web|title=Environmental Allergies: Symptoms |url=https://www.niaid.nih.gov/topics/environmental-allergies/Pages/symptoms.aspx |website=NIAID |access-date=19 June 2015 |date=22 April 2015 |archive-url=https://web.archive.org/web/20150618023408/http://www.niaid.nih.gov/topics/environmental-allergies/Pages/symptoms.aspx |archive-date=18 June 2015 }}</ref> Note that [[food intolerances]] and [[food poisoning]] are separate conditions.<ref name="NIH2012pdf">{{cite web |author1=National Institute of Allergy and Infectious Diseases |date=July 2012 |title=Food Allergy An Overview |url=https://www.niaid.nih.gov/topics/foodAllergy/Documents/foodallergy.pdf |archive-url=https://web.archive.org/web/20160305145206/http://www.niaid.nih.gov/topics/foodallergy/documents/foodallergy.pdf |archive-date=5 March 2016}}</ref><ref name=Bah2012>{{cite journal | vauthors = Bahna SL | title = Cow's milk allergy versus cow milk intolerance | journal = Annals of Allergy, Asthma & Immunology | volume = 89 | issue = 6 Suppl 1 | pages = 56–60 | date = December 2002 | pmid = 12487206 | doi = 10.1016/S1081-1206(10)62124-2 }}</ref>

<!-- Causes and diagnosis-->
Common [[allergen]]s include [[pollen]] and certain foods.<ref name=Con2007/> Metals and other substances may also cause such problems.<ref name=Con2007/> Food, [[insect sting]]s, and medications are common causes of severe reactions.<ref name=Kay2000/> Their development is due to both genetic and environmental factors.<ref name=Kay2000>{{cite journal | vauthors = Kay AB | title = Overview of 'allergy and allergic diseases: with a view to the future' | journal = British Medical Bulletin | volume = 56 | issue = 4 | pages = 843–64 | year = 2000 | pmid = 11359624 | doi = 10.1258/0007142001903481 | doi-access = free }}</ref> The underlying mechanism involves [[immunoglobulin E antibodies]] (IgE), part of the body's immune system, binding to an allergen and then to [[FcεRI|a receptor]] on [[mast cell]]s or [[basophil]]s where it triggers the release of inflammatory chemicals such as [[histamine]].<ref>{{cite web|title=How Does an Allergic Response Work? |url=https://www.niaid.nih.gov/topics/allergicdiseases/Pages/allergic-Response.aspx |website=NIAID |access-date=20 June 2015 |date=21 April 2015 |archive-url=https://web.archive.org/web/20150618023413/http://www.niaid.nih.gov/topics/allergicdiseases/Pages/allergic-Response.aspx |archive-date=18 June 2015 }}</ref> Diagnosis is typically based on a person's [[medical history]].<ref name=NIH2012pdf/> Further testing of the [[skin prick test|skin]] or blood may be useful in certain cases.<ref name=NIH2012pdf/> Positive tests, however, may not necessarily mean there is a significant allergy to the substance in question.<ref name=Cox2008>{{cite journal | vauthors = Cox L, Williams B, Sicherer S, Oppenheimer J, Sher L, Hamilton R, Golden D | title = Pearls and pitfalls of allergy diagnostic testing: report from the American College of Allergy, Asthma and Immunology/American Academy of Allergy, Asthma and Immunology Specific IgE Test Task Force | journal = Annals of Allergy, Asthma & Immunology | volume = 101 | issue = 6 | pages = 580–92 | date = December 2008 | pmid = 19119701 | doi = 10.1016/S1081-1206(10)60220-7 }}</ref>

<!-- Prevention and treatment -->
Early exposure of children to potential allergens may be protective.<ref name=Sic2014>{{cite journal | vauthors = Sicherer SH, Sampson HA | title = Food allergy: Epidemiology, pathogenesis, diagnosis, and treatment | journal = The Journal of Allergy and Clinical Immunology | volume = 133 | issue = 2 | pages = 291–307; quiz 308 | date = February 2014 | pmid = 24388012 | doi = 10.1016/j.jaci.2013.11.020 }}</ref> Treatments for allergies include avoidance of known allergens and the use of medications such as [[Corticosteroid|steroids]] and [[Histamine antagonist|antihistamines]].<ref name=NIH2015Imm/> In severe reactions, injectable [[adrenaline]] (epinephrine) is recommended.<ref name=Review09/> [[Allergen immunotherapy]], which gradually exposes people to larger and larger amounts of allergen, is useful for some types of allergies such as hay fever and reactions to insect bites.<ref name=NIH2015Imm/> Its use in food allergies is unclear.<ref name=NIH2015Imm>{{cite web|title=Allergen Immunotherapy |url=https://www.niaid.nih.gov/topics/allergicdiseases/Pages/allergen-immunotherapy.aspx |access-date=15 June 2015 |date=22 April 2015 |archive-url=https://web.archive.org/web/20150617122922/http://www.niaid.nih.gov/topics/allergicdiseases/Pages/allergen-immunotherapy.aspx |archive-date=17 June 2015 }}</ref>

<!-- Epidemiology and history -->
Allergies are common.<ref name=NIH2015Epi>{{cite web|title=Allergic Diseases |url=https://www.niaid.nih.gov/topics/allergicdiseases/Pages/default.aspx |website=NIAID |access-date=20 June 2015 |date=21 May 2015 |archive-url=https://web.archive.org/web/20150618023404/http://www.niaid.nih.gov/topics/allergicdiseases/pages/default.aspx |archive-date=18 June 2015 }}</ref> In the developed world, about 20% of people are affected by allergic rhinitis,<ref name=NEJM2015>{{cite journal | vauthors = Wheatley LM, Togias A | title = Clinical practice. Allergic rhinitis | journal = The New England Journal of Medicine | volume = 372 | issue = 5 | pages = 456–63 | date = January 2015 | pmid = 25629743 | pmc = 4324099 | doi = 10.1056/NEJMcp1412282 }}</ref> food allergy affects 10% of adults and 8% of children,<ref>{{Cite journal |last1=Bartha |first1=Irene |last2=Almulhem |first2=Noorah |last3=Santos |first3=Alexandra F. |date=2024-03-01 |title=Feast for thought: A comprehensive review of food allergy 2021-2023 |journal=Journal of Allergy and Clinical Immunology |volume=153 |issue=3 |pages=576–594 |doi=10.1016/j.jaci.2023.11.918 |pmid=38101757 |issn=0091-6749|pmc=11096837 }}</ref> and about 20% have or have had atopic dermatitis at some point in time.<ref>{{cite journal | vauthors = Thomsen SF | title = Atopic dermatitis: natural history, diagnosis, and treatment | journal = ISRN Allergy | volume = 2014 | pages = 354250 | date = 2014 | pmid = 25006501 | pmc = 4004110 | doi = 10.1155/2014/354250 | doi-access = free }}</ref> Depending on the country, about 1–18% of people have asthma.<ref name=GINA2015p2>{{cite web|url=http://www.ginasthma.org/local/uploads/files/GINA_Report_2015_Aug11.pdf |title=Global Strategy for Asthma Management and Prevention: Updated 2015 |publisher=Global Initiative for Asthma |year=2015 |page=2 |archive-url=https://web.archive.org/web/20151017163339/http://www.ginasthma.org/local/uploads/files/GINA_Report_2015_Aug11.pdf |archive-date=2015-10-17}}</ref><ref name=GINA2011p2>{{cite web |url=http://www.ginasthma.org/uploads/users/files/GINA_Report2011_May4.pdf |title=Global Strategy for Asthma Management and Prevention |publisher=Global Initiative for Asthma |year=2011|pages=2–5|archive-url=https://web.archive.org/web/20121120205023/http://www.ginasthma.org/uploads/users/files/GINA_Report2011_May4.pdf |archive-date=2012-11-20}}</ref> Anaphylaxis occurs in between 0.05–2% of people.<ref>{{cite book|first=Leslie C.|last=Grammer|title=Patterson's Allergic Diseases|date=2012|publisher=Lippincott Williams & Wilkins |isbn=978-1-4511-4863-3|edition=7|url=https://books.google.com/books?id=MWdT7W4_N8sC&pg=PA199}}</ref> Rates of many allergic diseases appear to be increasing.<ref name=Review09>{{cite journal | vauthors = Simons FE | title = Anaphylaxis: Recent advances in assessment and treatment | journal = The Journal of Allergy and Clinical Immunology | volume = 124 | issue = 4 | pages = 625–36; quiz 637–38 | date = October 2009 | pmid = 19815109 | doi = 10.1016/j.jaci.2009.08.025 | url = https://secure.muhealth.org/~ed/students/articles/JAClinImmun_124_p0625.pdf | archive-url = https://web.archive.org/web/20130627084618/https://secure.muhealth.org/~ed/students/articles/JAClinImmun_124_p0625.pdf | archive-date = 27 June 2013 }}</ref><ref>{{cite journal | vauthors = Anandan C, Nurmatov U, van Schayck OC, Sheikh A | title = Is the prevalence of asthma declining? Systematic review of epidemiological studies | journal = Allergy | volume = 65 | issue = 2 | pages = 152–67 | date = February 2010 | pmid = 19912154 | doi = 10.1111/j.1398-9995.2009.02244.x | s2cid = 19525219 | doi-access = free }}</ref><ref>{{Cite web|url=https://www.aaaai.org/conditions-and-treatments/library/allergy-library/prevalence-of-allergies-and-asthma|title=Increasing Rates of Allergies and Asthma| vauthors = Pongdee T |website=American Academy of Allergy, Asthma & Immunology}}</ref> The word "allergy" was first used by [[Clemens von Pirquet]] in 1906.<ref name="Kay2000" />