'''Anaphylaxis''' (Greek: ana- ‘again’‘against’ + phulaxisphylaxis ‘guarding’) is a serious, potentially fatal [[Allergy|allergic reaction]] and [[medical emergency]] that is rapid in onset and requires immediate medical attention regardless of the use of emergency medication on site.<ref name="Samp2006">{{cite journal |vauthors=Sampson HA, Muñoz-Furlong A, Campbell RL |title= Second symposium on the definition and management of anaphylaxis: summary report—Second National Institute of Allergy and Infectious Disease/Food Allergy and Anaphylaxis Network symposium |journal= The Journal of Allergy and Clinical Immunology |volume= 117 |issue= 2 |pages= 391–7 |date= February 2006 |pmid= 16461139|doi= 10.1016/j.jaci.2005.12.1303|display-authors= etal|doi-access= free |url=https://www.jacionline.org/article/S0091-6749%2805%2902723-5/fulltext }}</ref><ref name=Tint10>{{cite book |author= Tintinalli, Judith E. |title= Emergency Medicine: A Comprehensive Study Guide (Emergency Medicine (Tintinalli))|publisher= McGraw-Hill Companies |location= New York |year= 2010 |pages= 177–182 |isbn= 978-0-07-148480-0 }}</ref> It typically causes more than one of the following: an itchy rash, throat closing due to swelling that can obstruct or stop breathing; severe tongue swelling that can also interfere with or stop breathing; [[shortness of breath]], [[vomiting]], lightheadedness, loss of consciousness, [[Hypotension|low blood pressure]], and [[Shock (circulatory)|medical shock]].<ref name="Overview - Anaphylaxis">{{cite web |author1=NHS |title=Overview – Anaphylaxis |url=https://www.nhs.uk/conditions/anaphylaxis/ |website=NHS (National Health Service) |publisher=British government |access-date=4 March 2022 |location=United Kingdom |language=English |date=29 November 2019}}</ref><ref name=NIH2015/> These symptoms typically start in minutes to hours and then increase very rapidly to life-threatening levels.<ref name=NIH2015/> Urgent medical treatment is required to prevent serious harm and death, even if the patient has used an [[epipen]] or has taken other medications in response, and even if symptoms appear to be improving.<ref name="Overview - Anaphylaxis"/>
