Editing Anaphylaxis (section)

==Causes==
Anaphylaxis can occur in response to almost any foreign substance.<ref name=His11/> Common triggers include [[venom]] from [[Insect bites and stings|insect bites or stings]], foods, and [[Pharmaceutical drug|medication]].<ref name=CEA11/><ref>{{cite book|last=Worm|first=M|title=Anaphylaxis|chapter=Epidemiology of anaphylaxis|series=Chemical Immunology and Allergy|year=2010|volume=95|pages=12–21|pmid=20519879|doi=10.1159/000315935|isbn=978-3-8055-9441-7}}</ref> Foods are the most common trigger in children and young adults, while medications and insect bites and stings are more common in older adults.<ref name=World11/> Less common causes include: physical factors, biological agents such as [[semen]], [[latex]], [[Hormone|hormonal]] changes, food additives and colors, and topical medications.<ref name=Aus06/> Physical factors such as exercise (known as [[exercise-induced anaphylaxis]]) or temperature (either hot or cold) may also act as triggers through their direct effects on [[mast cell]]s.<ref name=World11/><ref name="APLS07">{{cite book |url=https://books.google.com/books?id=lLVfDC2dh54C&pg=PA69 |title=The pediatric emergency medicine resource |vauthors=Gausche-Hill M, Fuchs S, Yamamoto L |publisher=Jones & Bartlett |year=2007 |isbn=978-0-7637-4414-4 |edition=Rev. 4. |location=Sudbury, Mass. |pages=69 |archive-url=https://web.archive.org/web/20161223154615/https://books.google.com/books?id=lLVfDC2dh54C&pg=PA69 |archive-date=2016-12-23 |url-status=live}}</ref><ref>{{cite journal|last1=Feldweg|first1=AM|title=Exercise-Induced Anaphylaxis|journal=Immunology and Allergy Clinics of North America|date=May 2015|volume=35|issue=2|pages=261–75|doi=10.1016/j.iac.2015.01.005|pmid=25841550|type=Review}}</ref> Events caused by exercise are frequently associated with cofactors such as the ingestion of certain foods<ref name=Rosen2010/><ref name=Pravetton2016rev>{{cite journal|last1=Pravettoni|first1=V|last2=Incorvaia|first2=C|title=Diagnosis of exercise-induced anaphylaxis: current insights.|journal=Journal of Asthma and Allergy|date=2016|volume=9|pages=191–198|doi=10.2147/JAA.S109105|pmid=27822074|pmc=5089823|doi-access=free}}</ref> or taking an [[NSAID]].<ref name=Pravetton2016rev/> In [[aspirin-exacerbated respiratory disease]] (AERD), alcohol is a common trigger.<ref name= Stevens2015>{{cite journal |vauthors=Stevens W, Buchheit K, Cahill KN |title=Aspirin-Exacerbated Diseases: Advances in Asthma with Nasal Polyposis, Urticaria, Angioedema, and Anaphylaxis |journal=Curr Allergy Asthma Rep |volume=15 |issue=12 |pages=69 |date=December 2015 |pmid=26475526 |doi=10.1007/s11882-015-0569-2 |s2cid=2827520 }}</ref><ref name= Cardet2014/> During [[anesthesia]], [[Neuromuscular-blocking drug|neuromuscular blocking agents]], [[Antibacterial|antibiotics]], and latex are the most common causes.<ref>{{cite journal|last=Dewachter|first=P|author2=Mouton-Faivre, C |author3=Emala, CW|title=Anaphylaxis and anesthesia: controversies and new insights|journal=Anesthesiology|date=November 2009|volume=111|issue=5|pages=1141–50|pmid=19858877|doi=10.1097/ALN.0b013e3181bbd443|doi-access=free}}</ref> The cause remains unknown in 32–50% of cases, referred to as "[[idiopathic]] anaphylaxis."<ref name="editor 2010 223">{{cite book |last=Castells |first=Mariana C. |url=https://books.google.com/books?id=bEvnfm7V-LIC&pg=PA223 |title=Anaphylaxis and hypersensitivity reactions |publisher=Humana Press |year=2010 |isbn=978-1-60327-950-5 |location=New York |pages=223 |archive-url=https://web.archive.org/web/20161223161731/https://books.google.com/books?id=bEvnfm7V-LIC&pg=PA223 |archive-date=2016-12-23 |url-status=live}}</ref> Six vaccines (MMR, varicella, influenza, hepatitis B, tetanus, meningococcal) are recognized as a cause for anaphylaxis, and [[Human papillomavirus|HPV]] may cause anaphylaxis as well.<ref>{{cite book |url=https://www.ncbi.nlm.nih.gov/books/NBK190024/ |format=PDF |publisher=U.S. Institute of Medicine |title=Adverse Effects of Vaccines: Evidence and Causality |year=2011 |pmid=24624471 |access-date=2014-01-16 |url-status=live |archive-url=https://web.archive.org/web/20170908184018/https://www.ncbi.nlm.nih.gov/books/NBK190024/ |archive-date=2017-09-08 |isbn=9780309214353 |last1=Stratton |first1=K. |last2=Ford |first2=A. |last3=Rusch |first3=E. |last4=Clayton |first4=E. W. |author5=Committee to Review Adverse Effects of Vaccines |author6=Institute of Medicine }}</ref>

===Food and alcohol===
Many foods can trigger anaphylaxis; this may occur upon the first known ingestion.<ref name=CEA11/>  Common triggering foods vary around the world due to cultural cuisine.  In Western cultures, ingestion of or exposure to [[peanut]]s, [[wheat]], [[Nut (fruit)|nuts]], certain types of [[seafood]] like [[shellfish]], [[milk]], [[fruit]] and [[Egg (food)|eggs]] are the most prevalent causes.<ref name=World11/><ref name=Review09/> [[Sesame]] is common in the Middle East, while rice and [[chickpea]]s are frequently encountered as sources of anaphylaxis in Asia.<ref name=World11/> Severe cases are usually caused by ingesting the allergen,<ref name=CEA11/> but some people experience a severe reaction upon contact. Children can outgrow their allergies.  By age 16, 80% of children with anaphylaxis to milk or eggs and 20% who experience isolated anaphylaxis to peanuts can tolerate these foods.<ref name=His11/> Any type of alcohol, even in small amounts, can trigger anaphylaxis in people with AERD.<ref name= Stevens2015/><ref name= Cardet2014>{{cite journal |vauthors=Cardet JC, White AA, Barrett NA, Feldweg AM, Wickner PG, Savage J, Bhattacharyya N, Laidlaw TM |title=Alcohol-induced respiratory symptoms are common in patients with aspirin exacerbated respiratory disease |journal=J Allergy Clin Immunol Pract |volume=2 |issue=2 |pages=208–213 |date=2014 |pmid=24607050 |pmc=4018190 |doi=10.1016/j.jaip.2013.12.003 }}</ref>

===Medication===
Any medication may potentially trigger anaphylaxis. The most common are [[β-lactam antibiotic]]s (such as [[penicillin]]) followed by [[aspirin]] and [[Non-steroidal anti-inflammatory drug|NSAIDs]].<ref name=Review09/><ref name=WHO2015>{{cite journal|vauthors = Simons FE, Ebisawa M, Sanchez-Borges M, Thong BY, Worm M, Tanno LK, Lockey RF, El-Gamal YM, Brown SG, Park HS, Sheikh A |title=2015 update of the evidence base: World Allergy Organization anaphylaxis guidelines.|journal=The World Allergy Organization Journal|date=2015|volume=8|issue=1|pages=32|pmid=26525001|pmc=4625730|doi=10.1186/s40413-015-0080-1 |doi-access=free }}</ref> Other [[Antibacterial|antibiotics]] are implicated less frequently.<ref name=WHO2015/> Anaphylactic reactions to NSAIDs are either agent specific or occur among those that are structurally similar meaning that those who are allergic to one NSAID can typically tolerate a different one or different group of NSAIDs.<ref>{{cite journal|last1=Modena|first1=B|last2=White|first2=AA|last3=Woessner|first3=KM|title=Aspirin and Nonsteroidal Antiinflammatory Drugs Hypersensitivity and Management.|journal=Immunology and Allergy Clinics of North America|date=November 2017|volume=37|issue=4|pages=727–749|doi=10.1016/j.iac.2017.07.008|pmid=28965637}}</ref> Other relatively common causes include [[chemotherapy]], [[vaccine]]s, [[protamine]] and [[Herbalism|herbal]] preparations.<ref name=World11/> Some medications ([[vancomycin]], [[morphine]], [[Radiocontrast agent|x-ray contrast]] among others) cause anaphylaxis by directly triggering mast cell [[degranulation]].<ref name=CEA11/>

The frequency of a reaction to an agent partly depends on the frequency of its use and partly on its intrinsic properties.<ref name=Drug01>{{cite journal|last=Drain|first=KL|author2=Volcheck, GW|title=Preventing and managing drug-induced anaphylaxis|journal=Drug Safety |year=2001|volume=24|issue=11|pages=843–53|pmid=11665871|doi=10.2165/00002018-200124110-00005|s2cid=24840296}}</ref> Anaphylaxis to penicillin or [[cephalosporin]]s occurs only after it binds to proteins inside the body with some agents binding more easily than others.<ref name=Rosen2010/> Anaphylaxis to penicillin occurs once in every 2,000 to 10,000 courses of treatment, with death occurring in fewer than one in every 50,000 courses of treatment.<ref name=Rosen2010/> Anaphylaxis to aspirin and NSAIDs occurs in about one in every 50,000 persons.<ref name=Rosen2010/> If someone has a reaction to penicillin, his or her risk of a reaction to cephalosporins is greater but still less than one in 1,000.<ref name=Rosen2010/> The old radiocontrast agents caused reactions in 1% of cases, while the newer lower osmolar agents cause reactions in 0.04% of cases.<ref name=Drug01/>

===Venom===
[[Venom]] from stinging or biting insects such as [[Hymenoptera]] (ants, bees, and wasps) or [[Triatominae]] (kissing bugs) may cause anaphylaxis in susceptible people.<ref name=EAACI2014/><ref name="Klotz">{{cite journal|last=Klotz|first=JH|author2=Dorn, PL |author3=Logan, JL |author4=Stevens, L |author5=Pinnas, JL |author6=Schmidt, JO |author7=Klotz, SA |title="Kissing bugs": potential disease vectors and cause of anaphylaxis|journal=Clinical Infectious Diseases |date=Jun 15, 2010|volume=50|issue=12|pages=1629–34|pmid=20462351|doi=10.1086/652769|doi-access=free}}</ref><ref name=2001simonga>{{cite journal |first1=Simon G. A. |last1=Brown |first2=Qi-Xuan |last2=Wu |first3=G. Robert H. |last3=Kelsall |first4=Robert J. |last4=Heddle |first5=Brian A. |last5=Baldo |title=Fatal anaphylaxis following jack jumper ant sting in southern Tasmania |journal=Medical Journal of Australia |year=2001 |volume=175 |issue=11 |pages=644–647 |pmid=11837875 |url=http://www.mja.com.au/public/issues/175_12_171201/brown/brown.html |url-status=live |archive-url=https://web.archive.org/web/20120114054159/http://mja.com.au/public/issues/175_12_171201/brown/brown.html |archive-date=2012-01-14 |doi=10.5694/j.1326-5377.2001.tb143761.x |s2cid=2495334 |url-access=subscription }}</ref> Previous reactions that are anything more than a local reaction around the site of the sting, are a risk factor for future anaphylaxis;<ref>{{cite journal|last=Bilò|first=MB|title=Anaphylaxis caused by Hymenoptera stings: from epidemiology to treatment|journal=Allergy|date=July 2011|volume=66|issue=Suppl 95 |pages=35–7|pmid=21668850|doi=10.1111/j.1398-9995.2011.02630.x|s2cid=31238581}}</ref><ref>{{cite journal|last=Cox|first=L|author2=Larenas-Linnemann, D|author3=Lockey, RF |author4=Passalacqua, G|title=Speaking the same language: The World Allergy Organization Subcutaneous Immunotherapy Systemic Reaction Grading System|journal=The Journal of Allergy and Clinical Immunology|date=March 2010|volume=125|issue=3|pages=569–74, 574.e1–574.e7|pmid=20144472|doi=10.1016/j.jaci.2009.10.060|doi-access=free}}</ref> however, half of fatalities have had no previous systemic reaction.<ref>{{cite journal|last=Bilò|first=BM|author2=Bonifazi, F|title=Epidemiology of insect-venom anaphylaxis|journal=Current Opinion in Allergy and Clinical Immunology|date=August 2008|volume=8|issue=4|pages=330–7|pmid=18596590|doi=10.1097/ACI.0b013e32830638c5|s2cid=28384693}}</ref>

===Risk factors===
People with [[Atopy|atopic]] diseases such as [[asthma]], [[eczema]], or [[allergic rhinitis]] are at high risk of anaphylaxis from food, [[latex]], and [[radiocontrast agent]]s but not from injectable medications or stings.<ref name=World11/><ref name=CEA11/> One study in children found that 60% had a history of previous atopic diseases, and of children who die from anaphylaxis, more than 90% have asthma.<ref name=CEA11/> Those with [[mastocytosis]] or of a higher [[socioeconomic status]] are at increased risk.<ref name=World11/><ref name=CEA11/>