BACK TOTOP Browse A-ZSearchBrowse A-ZABCDEFGHIJKLMNOPQRSTUVWXYZ0-9 E-mail FormEmail ResultsName:Email address:Recipients Name:Recipients address:Message: Print-FriendlyBookmarksbookmarks-menuAnaphylaxisAnaphylactic reaction; Anaphylactic shock; Shock - anaphylactic; Allergic reaction - anaphylaxisAnaphylaxis is a life-threatening type of allergic reaction.Allergic reactionAllergic reactions are sensitivities to substances called allergens that come into contact with the skin, nose, eyes, respiratory tract, and gastroin...ImageRead Article Now Book Mark Article Causes Anaphylaxis is a severe, whole-body allergic reaction to a chemical that has become an allergen. An allergen is a substance that can cause an allergic reaction. AllergenAn allergen is a substance that can cause an allergic reaction. In some people, the immune system recognizes allergens as foreign or dangerous. As ...ImageRead Article Now Book Mark Article After being exposed to a substance such as bee sting venom, the person's immune system becomes sensitized to it. When the person is exposed to that allergen again, an allergic reaction may occur. Anaphylaxis happens quickly after the exposure. The condition is severe and involves the whole body.Tissues in different parts of the body release histamine and other substances. This causes the airways to tighten and leads to other symptoms.Some drugs (morphine, x-ray dye, aspirin, and others) may cause an anaphylactic-like reaction (anaphylactoid reaction) when people are first exposed to them. These reactions are not the same as the immune system response that occurs with true anaphylaxis. But, the symptoms, risk of complications, and treatment are the same for both types of reactions.Anaphylaxis can occur in response to any allergen. Common causes include:Drug allergies Drug allergiesDrug allergies are a group of symptoms caused by an allergic reaction to a drug (medicine).ImageRead Article Now Book Mark Article Food allergies Food allergiesA food allergy is a type of immune response triggered by eggs, peanuts, milk, shellfish or some other specific food.ImageRead Article Now Book Mark Article Insect bites/stingsInsect bites/stingsInsect bites and stings can cause an immediate skin reaction. The bite from fire ants and the sting from bees, wasps, and hornets are most often pai...ImageRead Article Now Book Mark Article Pollen and other inhaled allergens rarely cause anaphylaxis. Some people have an anaphylactic reaction with no known cause.Anaphylaxis is life threatening and can occur at any time. Risks include a history of any type of allergic reaction. Symptoms Symptoms develop quickly, often within seconds or minutes. They may include any of the following:Abdominal pain Feeling anxious Chest discomfort or tightness Diarrhea Difficulty breathing, coughing, wheezing, or high-pitched breathing sounds Difficulty swallowing Dizziness or lightheadedness DizzinessDizziness is a term that is often used to describe 2 different symptoms: lightheadedness and vertigo. Lightheadedness is a feeling that you might fai...ImageRead Article Now Book Mark Article LightheadednessFainting is a brief loss of consciousness due to a drop in blood flow to the brain. The episode most often lasts less than a couple of minutes and y...Read Article Now Book Mark Article Hives, itchiness, redness of the skin HivesHives are raised, often itchy, red bumps (welts) on the surface of the skin. They can be an allergic reaction to food or medicine. They can also ap...ImageRead Article Now Book Mark Article Nasal congestion Nausea or vomiting Palpitations PalpitationsPalpitations are feelings or sensations that your heart is pounding or racing. They can be felt in your chest, throat, or neck. You may:Have an unpl...ImageRead Article Now Book Mark Article Slurred speech Swelling of the face, eyes, or tongue Unconsciousness Exams and Tests The health care provider will examine the person and ask about what might have caused the condition.Tests for the allergen that caused anaphylaxis (if the cause is not obvious) may be done after treatment. Treatment Anaphylaxis is an emergency condition that needs medical attention right away. Call 911 or the local emergency number immediately.Check the person's airway, breathing, and circulation, which are known as the ABC's of Basic Life Support. A warning sign of dangerous throat swelling is a very hoarse or whispered voice, or coarse sounds when the person is breathing in air. If necessary, begin rescue breathing and CPR.CPRCPR stands for cardiopulmonary resuscitation. It is an emergency life-saving procedure that is done when someone's breathing or heartbeat has stoppe...Read Article Now Book Mark Article Call 911 or the local emergency number. Calm and reassure the person. If the allergic reaction is from a bee sting, scrape the stinger off the skin with something firm (such as a fingernail or plastic credit card). Do not use tweezers. Squeezing the stinger will release more venom. If the person has emergency allergy medicine on hand, help the person take or inject it. Do not give medicine through the mouth if the person is having difficulty breathing. Take steps to prevent shock. Have the person lie flat, raise the person's feet about 12 inches (30 centimeters), and cover the person with a coat or blanket. Do not place the person in this position if a head, neck, back, or leg injury is suspected, or if it causes discomfort. ShockShock is a life-threatening condition that occurs when the body is not getting enough blood flow. Lack of blood flow means the cells and organs do n...ImageRead Article Now Book Mark Article DO NOT:Do not assume that any allergy shots the person has already received will provide complete protection. Do not place a pillow under the person's head if they are having trouble breathing. This can block the airways. Do not give the person anything by mouth if they are having trouble breathing. Paramedics or other providers may place a tube through the nose or mouth into the airways. Or emergency surgery will be done to place a tube directly into the trachea.Place a tube through the nose or mouthEndotracheal intubation is a medical procedure in which a tube is placed into the windpipe (trachea) through the mouth or nose. In most emergency si...Read Article Now Book Mark Article Place a tube directly into the tracheaA tracheostomy is a surgical procedure to create an opening through the neck into the trachea (windpipe). A tube is most often placed through this o...ImageRead Article Now Book Mark Article The person may receive medicines to further reduce symptoms. Outlook (Prognosis) Anaphylaxis can be life threatening without prompt treatment. Symptoms usually do get better with the right therapy, so it is important to act right away. Possible Complications Without prompt treatment, anaphylaxis may result in:Blocked airway Cardiac arrest (no effective heartbeat) Cardiac arrestCardiac arrest occurs when the heart suddenly stops beating. When this happens, blood flow to the brain and the rest of the body also stops. Cardia...Read Article Now Book Mark Article Respiratory arrest (no breathing) Respiratory arrestBreathing that stops from any cause is called apnea. Slowed breathing is called bradypnea. Labored or difficult breathing is known as dyspnea....Read Article Now Book Mark Article Shock When to Contact a Medical Professional Call 911 or the local emergency number if you or someone you know develops severe symptoms of anaphylaxis. Or, go to the nearest emergency room. Prevention To prevent allergic reactions and anaphylaxis:Avoid triggers such as foods and medicines that have caused an allergic reaction in the past. Ask detailed questions about ingredients when you are eating away from home. Also carefully examine ingredient labels. If you have a child who is allergic to certain foods, introduce one new food at a time in small amounts so you can recognize an allergic reaction. People who know that they have had serious allergic reactions should wear a medical ID tag. If you have a history of serious allergic reactions, carry emergency medicines (such as a chewable antihistamine and injectable epinephrine or a bee sting kit) according to your provider's instructions. Do not use your injectable epinephrine on anyone else. They may have a condition (such as a heart problem) that could be worsened by this drug.Open ReferencesReferencesBarksdale AN, Muelleman RL. Allergy, hypersensitivity, and anaphylaxis. In: Walls RM, Hockberger RS, Gausche-Hill M, eds. Rosen's Emergency Medicine: Concepts and Clinical Practice. 9th ed. Philadelphia, PA: Elsevier; 2018:chap 109.Dreskin SC, Stitt JM. Anaphylaxis. In: Burks AW, Holgate ST, O'Hehir RE, et al, eds. Middleton's Allergy: Principles and Practice. 9th ed. Philadelphia, PA: Elsevier; 2020:chap 75.Schwartz LB. Systemic anaphylaxis, food allergy, and insect sting allergy. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 238.Shaker MS, Wallace DV, Golden DBK, et al. Anaphylaxis-a 2020 practice parameter update, systematic review, and Grading of Recommendations, Assessment, Development and Evaluation (GRADE) analysis. J Allergy Clin Immunol. 2020;145(4):1082-1123. PMID: 32001253 pubmed.ncbi.nlm.nih.gov/32001253/.AllVideoImagesTogShock - illustration Shock is a severe condition that occurs when not enough blood flows through the body, causing very low blood pressure, a lack of urine, and cell and tissue damage.ShockillustrationAllergic reactions - illustration Allergic reaction can be provoked by skin contact with poison plants, chemicals and animal scratches, as well as by insect stings. Ingesting or inhaling substances like pollen, animal dander, molds and mildew, dust, nuts and shellfish, may also cause allergic reaction. Medications such as penicillin and other antibiotics are also to be taken with care, to assure an allergic reflex is not triggered.Allergic reactionsillustrationAnaphylaxis - illustration Anaphylaxis is an acute systemic (whole body) type of allergic reaction which occurs when a person has become sensitized to a certain substance or allergen and is again exposed to the allergen. Some drugs, such as those used for pain relief or for x-rays, may cause an anaphylactoid reaction on first exposure. Histamines and other substances released into the bloodstream cause blood vessels to dilate and tissues to swell. Anaphylaxis may be life threatening if obstruction of the airway occurs, if blood pressure drops, or if heart arrhythmias occur.AnaphylaxisillustrationHives - illustration Hives are raised red welts of various size on the surface of the skin, often itchy, which come and go. Also called uticaria, hives is usually part of an allergic reaction to drugs or food. The term dermatitis describes an inflammatory response of the skin, caused by contact with allergens or irritants, exposure to sunlight, or by poor circulation, even stress. AVOID SCRATCHING. Scratching the rash may spread the inflammation, lead to infection and even leave scars.HivesillustrationFood allergies - illustration The body's immune system normally reacts to the presence of toxins, bacteria or viruses by producing a chemical reaction to fight these invaders. However, sometimes the immune system reacts to ordinarily benign substances such as food or pollen, to which it has become sensitive. This overreaction can cause symptoms from the mild (hives) to the severe (anaphylactic shock) upon subsequent exposure to the substance. An actual food allergy, as opposed to simple intolerance due to the lack of digesting enzymes, is indicated by the production of antibodies to the food allergen, and by the release of histamines and other chemicals into the blood.Food allergiesillustrationInsect stings and allergy - illustration Allergic reaction to bee stings occurs when a person becomes sensitized to the venom from a previous sting. This reaction is different from the reaction to the poison in the bite of a black widow spider, which injects a potent toxin into the blood. Ordinarily, bee venom is not toxic and will only cause local pain and swelling. The allergic reaction comes when the immune system is oversensitized to the venom and produces antibodies to it. Histamines and other substances are released into the bloodstream, causing blood vessels to dilate and tissues to swell. Severe reactions can lead to anaphylactic shock, a life-threatening series of symptoms including swelling of the throat and difficulty breathing. Persons who develop an allergy to bee stings should carry prescription bee sting kits to counteract the reaction to bee venom.Insect stings and allergyillustrationAllergic reactions to medication - illustration A true allergy to a medication is different than a simple adverse reaction to the drug. The allergic reaction occurs when the immune system, having been exposed to the drug before, creates antibodies to it. On subsequent exposure to the drug these antibodies cause release of histamines. If severe, this reaction can result in a life-threatening situation known as anaphylactic shock. Allergic reactions to medicationillustrationAntibodies - illustration Antigens are large molecules (usually proteins) on the surface of cells, viruses, fungi, bacteria, and some non-living substances such as toxins, chemicals, drugs, and foreign particles. The immune system recognizes antigens and produces antibodies that destroy substances containing antigens. AntibodiesillustrationShock - illustration Shock is a severe condition that occurs when not enough blood flows through the body, causing very low blood pressure, a lack of urine, and cell and tissue damage.ShockillustrationAllergic reactions - illustration Allergic reaction can be provoked by skin contact with poison plants, chemicals and animal scratches, as well as by insect stings. Ingesting or inhaling substances like pollen, animal dander, molds and mildew, dust, nuts and shellfish, may also cause allergic reaction. Medications such as penicillin and other antibiotics are also to be taken with care, to assure an allergic reflex is not triggered.Allergic reactionsillustrationAnaphylaxis - illustration Anaphylaxis is an acute systemic (whole body) type of allergic reaction which occurs when a person has become sensitized to a certain substance or allergen and is again exposed to the allergen. Some drugs, such as those used for pain relief or for x-rays, may cause an anaphylactoid reaction on first exposure. Histamines and other substances released into the bloodstream cause blood vessels to dilate and tissues to swell. Anaphylaxis may be life threatening if obstruction of the airway occurs, if blood pressure drops, or if heart arrhythmias occur.AnaphylaxisillustrationHives - illustration Hives are raised red welts of various size on the surface of the skin, often itchy, which come and go. Also called uticaria, hives is usually part of an allergic reaction to drugs or food. The term dermatitis describes an inflammatory response of the skin, caused by contact with allergens or irritants, exposure to sunlight, or by poor circulation, even stress. AVOID SCRATCHING. Scratching the rash may spread the inflammation, lead to infection and even leave scars.HivesillustrationFood allergies - illustration The body's immune system normally reacts to the presence of toxins, bacteria or viruses by producing a chemical reaction to fight these invaders. However, sometimes the immune system reacts to ordinarily benign substances such as food or pollen, to which it has become sensitive. This overreaction can cause symptoms from the mild (hives) to the severe (anaphylactic shock) upon subsequent exposure to the substance. An actual food allergy, as opposed to simple intolerance due to the lack of digesting enzymes, is indicated by the production of antibodies to the food allergen, and by the release of histamines and other chemicals into the blood.Food allergiesillustrationInsect stings and allergy - illustration Allergic reaction to bee stings occurs when a person becomes sensitized to the venom from a previous sting. This reaction is different from the reaction to the poison in the bite of a black widow spider, which injects a potent toxin into the blood. Ordinarily, bee venom is not toxic and will only cause local pain and swelling. The allergic reaction comes when the immune system is oversensitized to the venom and produces antibodies to it. Histamines and other substances are released into the bloodstream, causing blood vessels to dilate and tissues to swell. Severe reactions can lead to anaphylactic shock, a life-threatening series of symptoms including swelling of the throat and difficulty breathing. Persons who develop an allergy to bee stings should carry prescription bee sting kits to counteract the reaction to bee venom.Insect stings and allergyillustrationAllergic reactions to medication - illustration A true allergy to a medication is different than a simple adverse reaction to the drug. The allergic reaction occurs when the immune system, having been exposed to the drug before, creates antibodies to it. On subsequent exposure to the drug these antibodies cause release of histamines. If severe, this reaction can result in a life-threatening situation known as anaphylactic shock. Allergic reactions to medicationillustrationAntibodies - illustration Antigens are large molecules (usually proteins) on the surface of cells, viruses, fungi, bacteria, and some non-living substances such as toxins, chemicals, drugs, and foreign particles. The immune system recognizes antigens and produces antibodies that destroy substances containing antigens. AntibodiesillustrationRelated Information Allergic reactions(Injury)Wheezing(Symptoms)Breathing difficulty(Symptoms)Shock(Injury)Pulmonary edema(Condition)Hives(Condition)Angioedema(Condition)Arrhythmias(Condition)Insect bites and stings(Injury)Food allergy(Condition) Review Date: 1/23/2022 Reviewed By: Stuart I. Henochowicz, MD, FACP, Clinical Professor of Medicine, Division of Allergy, Immunology, and Rheumatology, Georgetown University Medical School, Washington, DC. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. No warranty of any kind, either expressed or implied, is made as to the accuracy, reliability, timeliness, or correctness of any translations made by a third-party service of the information provided herein into any other language. © 1997- A.D.A.M., a business unit of Ebix, Inc. Any duplication or distribution of the information contained herein is strictly prohibited. © 1997- All rights reserved. A.D.A.M. content is best viewed in IE9 or above, Firefox and Google Chrome browser.Content is best viewed in IE9 or above, Firefox and Google Chrome browser.
AnaphylaxisAnaphylactic reaction; Anaphylactic shock; Shock - anaphylactic; Allergic reaction - anaphylaxisAnaphylaxis is a life-threatening type of allergic reaction.Allergic reactionAllergic reactions are sensitivities to substances called allergens that come into contact with the skin, nose, eyes, respiratory tract, and gastroin...ImageRead Article Now Book Mark Article Causes Anaphylaxis is a severe, whole-body allergic reaction to a chemical that has become an allergen. An allergen is a substance that can cause an allergic reaction. AllergenAn allergen is a substance that can cause an allergic reaction. In some people, the immune system recognizes allergens as foreign or dangerous. As ...ImageRead Article Now Book Mark Article After being exposed to a substance such as bee sting venom, the person's immune system becomes sensitized to it. When the person is exposed to that allergen again, an allergic reaction may occur. Anaphylaxis happens quickly after the exposure. The condition is severe and involves the whole body.Tissues in different parts of the body release histamine and other substances. This causes the airways to tighten and leads to other symptoms.Some drugs (morphine, x-ray dye, aspirin, and others) may cause an anaphylactic-like reaction (anaphylactoid reaction) when people are first exposed to them. These reactions are not the same as the immune system response that occurs with true anaphylaxis. But, the symptoms, risk of complications, and treatment are the same for both types of reactions.Anaphylaxis can occur in response to any allergen. Common causes include:Drug allergies Drug allergiesDrug allergies are a group of symptoms caused by an allergic reaction to a drug (medicine).ImageRead Article Now Book Mark Article Food allergies Food allergiesA food allergy is a type of immune response triggered by eggs, peanuts, milk, shellfish or some other specific food.ImageRead Article Now Book Mark Article Insect bites/stingsInsect bites/stingsInsect bites and stings can cause an immediate skin reaction. The bite from fire ants and the sting from bees, wasps, and hornets are most often pai...ImageRead Article Now Book Mark Article Pollen and other inhaled allergens rarely cause anaphylaxis. Some people have an anaphylactic reaction with no known cause.Anaphylaxis is life threatening and can occur at any time. Risks include a history of any type of allergic reaction. Symptoms Symptoms develop quickly, often within seconds or minutes. They may include any of the following:Abdominal pain Feeling anxious Chest discomfort or tightness Diarrhea Difficulty breathing, coughing, wheezing, or high-pitched breathing sounds Difficulty swallowing Dizziness or lightheadedness DizzinessDizziness is a term that is often used to describe 2 different symptoms: lightheadedness and vertigo. Lightheadedness is a feeling that you might fai...ImageRead Article Now Book Mark Article LightheadednessFainting is a brief loss of consciousness due to a drop in blood flow to the brain. The episode most often lasts less than a couple of minutes and y...Read Article Now Book Mark Article Hives, itchiness, redness of the skin HivesHives are raised, often itchy, red bumps (welts) on the surface of the skin. They can be an allergic reaction to food or medicine. They can also ap...ImageRead Article Now Book Mark Article Nasal congestion Nausea or vomiting Palpitations PalpitationsPalpitations are feelings or sensations that your heart is pounding or racing. They can be felt in your chest, throat, or neck. You may:Have an unpl...ImageRead Article Now Book Mark Article Slurred speech Swelling of the face, eyes, or tongue Unconsciousness Exams and Tests The health care provider will examine the person and ask about what might have caused the condition.Tests for the allergen that caused anaphylaxis (if the cause is not obvious) may be done after treatment. Treatment Anaphylaxis is an emergency condition that needs medical attention right away. Call 911 or the local emergency number immediately.Check the person's airway, breathing, and circulation, which are known as the ABC's of Basic Life Support. A warning sign of dangerous throat swelling is a very hoarse or whispered voice, or coarse sounds when the person is breathing in air. If necessary, begin rescue breathing and CPR.CPRCPR stands for cardiopulmonary resuscitation. It is an emergency life-saving procedure that is done when someone's breathing or heartbeat has stoppe...Read Article Now Book Mark Article Call 911 or the local emergency number. Calm and reassure the person. If the allergic reaction is from a bee sting, scrape the stinger off the skin with something firm (such as a fingernail or plastic credit card). Do not use tweezers. Squeezing the stinger will release more venom. If the person has emergency allergy medicine on hand, help the person take or inject it. Do not give medicine through the mouth if the person is having difficulty breathing. Take steps to prevent shock. Have the person lie flat, raise the person's feet about 12 inches (30 centimeters), and cover the person with a coat or blanket. Do not place the person in this position if a head, neck, back, or leg injury is suspected, or if it causes discomfort. ShockShock is a life-threatening condition that occurs when the body is not getting enough blood flow. Lack of blood flow means the cells and organs do n...ImageRead Article Now Book Mark Article DO NOT:Do not assume that any allergy shots the person has already received will provide complete protection. Do not place a pillow under the person's head if they are having trouble breathing. This can block the airways. Do not give the person anything by mouth if they are having trouble breathing. Paramedics or other providers may place a tube through the nose or mouth into the airways. Or emergency surgery will be done to place a tube directly into the trachea.Place a tube through the nose or mouthEndotracheal intubation is a medical procedure in which a tube is placed into the windpipe (trachea) through the mouth or nose. In most emergency si...Read Article Now Book Mark Article Place a tube directly into the tracheaA tracheostomy is a surgical procedure to create an opening through the neck into the trachea (windpipe). A tube is most often placed through this o...ImageRead Article Now Book Mark Article The person may receive medicines to further reduce symptoms. Outlook (Prognosis) Anaphylaxis can be life threatening without prompt treatment. Symptoms usually do get better with the right therapy, so it is important to act right away. Possible Complications Without prompt treatment, anaphylaxis may result in:Blocked airway Cardiac arrest (no effective heartbeat) Cardiac arrestCardiac arrest occurs when the heart suddenly stops beating. When this happens, blood flow to the brain and the rest of the body also stops. Cardia...Read Article Now Book Mark Article Respiratory arrest (no breathing) Respiratory arrestBreathing that stops from any cause is called apnea. Slowed breathing is called bradypnea. Labored or difficult breathing is known as dyspnea....Read Article Now Book Mark Article Shock When to Contact a Medical Professional Call 911 or the local emergency number if you or someone you know develops severe symptoms of anaphylaxis. Or, go to the nearest emergency room. Prevention To prevent allergic reactions and anaphylaxis:Avoid triggers such as foods and medicines that have caused an allergic reaction in the past. Ask detailed questions about ingredients when you are eating away from home. Also carefully examine ingredient labels. If you have a child who is allergic to certain foods, introduce one new food at a time in small amounts so you can recognize an allergic reaction. People who know that they have had serious allergic reactions should wear a medical ID tag. If you have a history of serious allergic reactions, carry emergency medicines (such as a chewable antihistamine and injectable epinephrine or a bee sting kit) according to your provider's instructions. Do not use your injectable epinephrine on anyone else. They may have a condition (such as a heart problem) that could be worsened by this drug.Open ReferencesReferencesBarksdale AN, Muelleman RL. Allergy, hypersensitivity, and anaphylaxis. In: Walls RM, Hockberger RS, Gausche-Hill M, eds. Rosen's Emergency Medicine: Concepts and Clinical Practice. 9th ed. Philadelphia, PA: Elsevier; 2018:chap 109.Dreskin SC, Stitt JM. Anaphylaxis. In: Burks AW, Holgate ST, O'Hehir RE, et al, eds. Middleton's Allergy: Principles and Practice. 9th ed. Philadelphia, PA: Elsevier; 2020:chap 75.Schwartz LB. Systemic anaphylaxis, food allergy, and insect sting allergy. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 238.Shaker MS, Wallace DV, Golden DBK, et al. Anaphylaxis-a 2020 practice parameter update, systematic review, and Grading of Recommendations, Assessment, Development and Evaluation (GRADE) analysis. J Allergy Clin Immunol. 2020;145(4):1082-1123. PMID: 32001253 pubmed.ncbi.nlm.nih.gov/32001253/.