Anaphylaxis: MedlinePlus Medical Encyclopedia 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 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 . Call 911. 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. 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 . 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 Shock When to Contact a Medical Professional Call 911 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. Alternative Names Anaphylactic reaction; Anaphylactic shock; Shock - anaphylactic; Allergic reaction - anaphylaxis Images Antibodies References Brown SGA, Kemp SF, Lieberman PL. Anaphylaxis. In: Adkinson NF Jr, Bochner BS, Burks AW, et al, eds.

Middleton's Allergy: Principles and Practice. 8th ed. Philadelphia, PA: Elsevier Saunders; 2014:chap 77. Lieberman P, Nicklas RA, Randolph C, et al. Anaphylaxis – a practice parameter update 2015. Ann Allergy Asthma Immunol. 2015;115(5):341-384. PMID: 26505932 . Schwartz LB. Systemic anaphylaxis, food allergy, and insect sting allergy. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine. 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 253. Tran TP, Muelleman RL. Allergy, hypersensitivity, angioedema, and anaphylaxis. In: Marx JA, Hockberger RS, Walls RM, et al, eds. Rosen's Emergency Medicine: Concepts and Clinical Practice. 8th ed. Philadelphia, PA: Elsevier Saunders; 2014:chap 119.

Read More Anaphylaxis | definition of anaphylaxis by Medical dictionary Anaphylaxis | definition of anaphylaxis by Medical dictionary Anaphylaxis is a rapidly progressing, life-threatening allergic reaction. Description Anaphylaxis is a type of allergic reaction, in which the immune system responds to otherwise harmless substances from the environment. Unlike other allergic reactions, however, anaphylaxis can kill. Reaction may begin within minutes or even seconds of exposure, and rapidly progress to cause airway constriction, skin and intestinal irritation, and altered heart rhythms. In severe cases, it can result in complete airway obstruction, shock , and death . Causes and symptoms Causes Like the majority of other allergic reactions, anaphylaxis is caused by the release of histamine and other chemicals from mast cells. Mast cells are a type of white blood cell and they are found in large numbers in the tissues that regulate exchange with the environment: the airways, digestive system, and skin. On their surfaces, mast cells display antibodies called IgE (immunoglobulin type E). These antibodies are designed to detect environmental substances to which the immune system is sensitive. Substances from a genuinely threatening source, such as bacteria or viruses, are called antigens.

A substance that most people tolerate well, but to which others have an allergic response, is called an allergen. When IgE antibodies bind with allergens, they cause the mast cell to release histamine and other chemicals, which spill out onto neighboring cells. The interaction of these chemicals with receptors on the surface of blood vessels causes the vessels to leak fluid into surrounding tissues, causing fluid accumulation, redness, and swelling. On the smooth muscle cells of the airways and digestive system, they cause constriction. On nerve endings, they increase sensitivity and cause itching . In anaphylaxis, the dramatic response is due both to extreme hypersensivity to the allergen and its usually systemic distribution. Allergens are more likely to cause anaphylaxis if they are introduced directly into the circulatory system by injection. However, exposure by ingestion, inhalation, or skin contact can also cause anaphylaxis. In some cases, anaphylaxis may develop over time from less severe allergies . Anaphylaxis is most often due to allergens in foods, drugs, and insect venom.

Specific causes include: Fish, shellfish, and mollusks Stings of bees, wasps, or hornets Papain from meat tenderizers Vaccines, including flu and measles vaccines Penicillin Latex, from exam gloves or condoms, for example. Exposure to cold or exercise can trigger anaphylaxis in some individuals. Key terms ACTH — Adrenocorticotropic hormone, a hormone normally produced by the pituitary gland, sometimes taken as a treatment for arthritis and other disorders. Antibody — An immune system protein which binds to a substance from the environment. NSAIDs — Non-steroidal antiinflammatory drugs, including aspirin and ibuprofen. Tracheostomy tube — A tube which is inserted into an incision in the trachea (tracheostomy) to relieve upper airway obstruction. Symptoms Swelling and irritation of the tongue or mouth Swelling of the sinuses Strong, very rapid heartbeat ( palpitations ) Loss of consciousness. Not all symptoms may be present. Diagnosis Anaphylaxis is diagnosed based on the rapid development of symptoms in response to a suspect allergen.

Identification of the culprit may be done with RAST testing, a blood test that identifies IgE reactions to specific allergens. Skin testing may be done for less severe anaphylactic reactions. Treatment Emergency treatment of anaphylaxis involves injection of adrenaline (epinephrine) which constricts blood vessels and counteracts the effects of histamine. Oxygen may be given, as well as intravenous replacement fluids. Antihistamines may be used for skin rash, and aminophylline for bronchial constriction. If the upper airway is obstructed, placement of a breathing tube or tracheostomy tube may be needed. Prognosis The rapidity of symptom development is an indication of the likely severity of reaction: the faster symptoms develop, the more severe the ultimate reaction. Prompt emergency medical attention and close monitoring reduces the likelihood of death. Nonetheless, death is possible from severe anaphylaxis. For most people who receive rapid treatment, recovery is complete. Prevention Avoidance of the allergic trigger is the only reliable method of preventing anaphylaxis. For insect allergies, this requires recognizing likely nest sites.

Preventing food allergies requires knowledge of the prepared foods or dishes in which the allergen is likely to occur, and careful questioning about ingredients when dining out. Use of a Medic-Alert tag detailing drug allergies is vital to prevent inadvertent administration during a medical emergency. People prone to anaphylaxis should carry an "Epi-pen" or "Ana-kit," which contain an adrenaline dose ready for injection. Resources The Meck Page. February 20, 1998. anaphylaxis [an″ah-fi-lak´sis] an unusual or exaggerated allergic reaction of an organism to foreign protein or other substances. Substances most likely to cause this include drugs such as antibiotics, local anesthetics, and codeine; drugs prepared from animals, such as insulin, adrenocorticotropic hormone, and enzymes; diagnostic agents, such as iodinated x-ray contrast media; biologicals used to provide immunity, such as vaccines, antitoxins, and gamma globulin; protein foods; the venom of bees, wasps, and hornets; and pollens, molds, and animal dander. The latex in gloves or Foley catheters may cause a reaction in sensitive individuals. Physiologic Basis.

Anaphylaxis is an allergen-reagin reaction brought about by large quantities of IgE antibodies ( immunoglobulins ) that respond to the presence of foreign agents. Individuals who have an anaphylactoid type of immune response have a familial predisposition to overreact in the presence of an allergen because of their tendency to produce an overabundance of IgE antibodies. When an allergen enters the body reagins (IgE antibodies), which are attached to cells throughout the body, interact with the allergens. This interaction is destructive to some of the body's cells. If the interaction is severe, the outcome can be fatal. During the interaction mast cells and eosinophils release histamine, slow-reacting substance of anaphylaxis (SRS-A), bradykinin, and enzymes. Histamine brings about bronchospasm, widespread peripheral vasodilation, and increased permeability of the capillaries. SRS-A causes increased constriction of the bronchioles and bronchi. Bradykinin has effects similar to those of histamine. Together they promote collapse of the vascular network by permitting the loss of fluid from the blood vessels into the interstitial fluid compartment. Clinical Manifestations.

If the allergen comes into contact with cell-bound IgE in the respiratory tract, the tissues of the mucosa release chemical mediators that produce the symptoms of asthma and hay fever . An insect bite or sting can produce localized swelling, redness, and itching, or a more severe systemic reaction. Local anaphylactic reactions usually produce mildly irritating symptoms, which should not be ignored because the reaction can rapidly escalate into a systemic response involving cells throughout the body. The patient may then experience generalized itching, swelling, and urticaria. As the process continues, respiration is impaired because of bronchospasm and laryngeal edema. If an airway is not maintained and supplemental oxygen provided, the person will die of respiratory failure. Another life-threatening series of events is related to vascular collapse resulting from a shift in body fluid. The symptoms are hypotension, decreasing levels of consciousness, tachycardia, and diminished production of urine. Without effective treatment these symptoms progress to profound shock and death. Treatment and Patient Care. Mild anaphylaxis can be treated with antihistamines , local applications of cold to minimize swelling, and topical applications of medications to relieve itching and soothe the skin.

All anaphylactic reactions require careful assessment and monitoring, and the patient should be instructed to seek additional help if he or she experiences dizziness, heart palpitations, or prolonged or spreading edema anywhere in the body. The drug of choice in the initial treatment of severe anaphylaxis is epinephrine , administered intravenously, subcutaneously, sublingually, or by intermittent positive pressure breathing. The mode of administration is governed by the urgency of the situation and the presenting symptoms. Epinephrine causes bronchodilation, reduces laryngeal spasm, and elevates the blood pressure. Steroid therapy is initiated to counteract the effects of histamine by decreasing capillary permeability. Acting as antiinflammatory agents, steroids also stabilize mast cells and prevent further release of chemical mediators. Supportive measures include administration of intravenous fluids and plasma to restore intravascular fluid volume. Pressor agents, such as dopamine , norepinephrine , and isoproterenol , are given to increase and maintain blood pressure. The best way to control anaphylaxis is by preventing it from happening in the first place, but this is not always possible.

A person engaging in normal activities outside the clinical setting can accidentally come in contact with an allergen. An allergic individual should be prepared for such an event by understanding his or her allergy and knowing what actions to take. Those with known atopic allergies should wear a medical identification necklace or bracelet, and those who undergo systemic reactions should carry with them at all times a kit containing diphenhydramine ( Benadryl ), a syringe and needle, and vials of epinephrine . These kits require a written prescription from a primary health care provider. In the clinical setting, all health care personnel should be alert to the need for identifying patients with known allergies and communicating this information to their co-workers. Emergency equipment should be readily available in all places where drugs or diagnostic agents with a risk of provoking anaphylaxis are administered. active anaphylaxis that produced by injection of a foreign protein. antiserum anaphylaxis (passive anaphylaxis) that resulting from injection of serum of a sensitized person into a normal person.

passive cutaneous anaphylaxis PCA; localized anaphylaxis passively transferred by intradermal injection of an antibody and, after a latent period (about 24 to 72 hours), intravenous injection of the homologous antigen and Evans blue dye; blueing of the skin at the site of the intradermal injection is evidence of the permeability reaction. Used in studies of antibodies causing immediate hypersensitivity reactions. reverse anaphylaxis that following injection of antigen, succeeded by injection of antiserum. an·a·phy·lax·is (an'ă-fi-lak'sis), An induced systemic or generalized sensitivity; at times the term anaphylaxis is used for anaphylactic shock. The term is commonly used to denote the clinical reaction seen with system IgE-mediated hypersensitivity reaction. Multivalent antigen crosslinks IgE on the surface of tissues mast cells, causing degranulation with release of preformed mediators (for example, histamine). Generation of newly synthesized mediators occurs rapidly. The physiologic manifestations reflect the biologic effects of these mediators. Cutaneous symptoms include pruritus, erythema, urticaria, and angioedema.

Respiratory compromise can come from laryngeal obstruction or bronchospasm. Cardiac effects include arrhythmia, hypotension, and shock. The reaction may be fatal if asphyxiation or cardiovascular collapse occurs. [G. ana, away from, back from, + phylaxis, protection] anaphylaxis /ana·phy·lax·is/ (-fĭ-lak´sis) anaphylactic shock; a manifestation of immediate hypersensitivity in which exposure of a sensitized individual to a specific antigen or hapten results in life-threatening respiratory distress, usually followed by vascular collapse and shock and accompanied by urticaria, pruritus, and angioedema. active anaphylaxis that produced by injection of a foreign protein. (ăn′ə-fə-lăk′sĭs) n. A sudden, usually systemic allergic reaction, characterized by vasodilation resulting in decreased blood pressure, smooth muscle contraction resulting in shortness of breath, and hives, caused by hypersensitivity induced by a secondary exposure to a foreign substance, such as a drug or protein, after an initial sensitizing exposure.

an′a·phy·lac′tic (-lăk′tĭk), an′a·phy·lac′toid (-toid) adj. an′a·phy·lac′ti·cal·ly adv. anaphylaxis [an′əfilak′sis] Etymology: Gk, ana + phylaxis, protection an exaggerated, life-threatening hypersensitivity reaction to a previously encountered antigen. It is mediated by antibodies of the E or G class of immunoglobulins and results in the release of chemical mediators from mast cells. The reaction may consist of a localized wheal-and-flare reaction of generalized itching, hyperemia, angioedema, and in severe cases vascular collapse, bronchospasm, and shock. The severity of symptoms depends on the original sensitizing dose of the antigen, the number and distribution of antibodies, and the route of entry and dose of subsequently encountered antigen. Penicillin injection is the most common cause of anaphylactic shock.

Insect stings, radiopaque contrast media containing iodide, aspirin, antitoxins prepared with animal sera, and allergens used in testing and desensitizing patients who are hypersensitive also produce anaphylaxis in some individuals. Kinds of anaphylaxis are aggregate anaphylaxis , antiserum anaphylaxis , cutaneous anaphylaxis , cytotoxic anaphylaxis , indirect anaphylaxis , and inverse anaphylaxis. anaphylactic, adj. observations Manifestations can range from mild to severe. Mild symptoms include queasiness, anxiety, urticaria, itching, flushing, sneezing, nasal congestion, runny nose, cough, conjunctivitis, abdominal cramps, and tachycardia. Moderate reactions include a range of symptoms, including malaise; urticaria; pulmonary congestion, dyspnea, wheezing, and bronchospasm; hoarseness; edema of the periorbital tissue and/or tongue, larynx, and pharynx; dysphagia; nausea; vomiting; diarrhea; hypotension; syncope; and confusion.

Severe anaphylaxis presents with pallor and cyanosis, stridor, airway obstruction, and hypoxia. If not treated immediately, respiratory arrest, cardiac arrhythmia, circulatory collapse, seizures, coma, and death rapidly ensue. interventions Treatment centers on immediate and aggressive management of emerging symptoms. Maintaining the airway and blood pressure is critical. EpINEPHrine and other drugs are used to counteract effects of mediator release and to block further mediator release. Vasoconstrictors are used to maintain blood pressure. Intubation or tracheostomy may be necessary to maintain an airway. nursing considerations The patient suffering an allergic reaction needs careful monitoring for signs of respiratory distress, hypotension, and decreased circulatory volume. Nursing interventions for anaphylactic shock center on the promotion of adequate ventilation and tissue perfusion. Airway needs are maintained, vital signs are monitored for hypotension, blood gases are monitored for acidosis, ECG is monitored for dysrhythmias, and fluid volume is replaced with IV solutions.

Education about prevention of future attacks should include instruction in prophylaxis, such as avoiding known allergens, wearing a Medic Alert bracelet or necklace that identifies allergies, and ensuring that all medical records have allergies highlighted in a prominent place. Those with severe allergic reactions should consider carrying an anaphylaxis kit with preloaded epINEPHrine syringes. EpiPen used for anaphylaxis anaphylaxis A brisk immune response resulting from the binding of IgE antibodies to high-affinity IgE receptors on mast cells or basophils, with the release of histamine and tryptase and secretion of leukotrienes and prostaglandins; laryngeal oedema may cause death by asphyxia. The postmortem examination is often negative; the diagnosis requires history of the terminal events. Autopsy findings Cutaneous urticaria and angioedema, pharyngeal or laryngeal spasm, upper airway oedema, lower airways obstruction due to bronchospasm and mucus plugging, hyperinflation of lungs, petechial haemorrhage.

Anaphylactic death is quickest with drugs (5 minutes), slower with stings (12 minutes) and slowest with food (30 minutes). Lab workup Tissue eosinophilia, serum mast cell tryptase, allergen-specific IgE antibodies. Management Adrenaline (with the caveat that too much adrenaline can also kill the patient by causing massive pulmonary oedema). Fatal anaphylaxis—causative agents • Peanuts, as well as pecans and other nuts; • Prawns and other shellfish; • Milk and other dairy products. Drugs • Antibiotics—classically penicillin, but increasingly cephalosporins, amoxycillin, ampicillin; • Anaesthetics—e.g., suxamethonium (succinylcholine), thiopental, acetazolamide, protamine; • Radiocontrast media—especially ionic media, technitium. Venoms Typically cause death by shock, as well as laryngeal oedema and complete upper airway obstruction, usually accompanied by petechial haemorrhage on mucosal and serosal surfaces (a typical finding in asphyxia).

Miscellaneous Chymopapain, platinum compounds, phenylenediamine (used as a hair dye); even skin prick tests can be fatal.

transfusion reaction Blood transfusion reaction, incompatibility reaction Transfusion medicine Any untoward response to the transfusion of non-self blood products, in particular RBCs, which evokes febrile reactions that are either minor–occurring in 1:40 transfusions and attributed to nonspecific leukocyte-derived pyrogens, or major–occurring in 1:3000 transfusions and caused by a true immune reaction, which is graded according to the presence of urticaria, itching, chills, fever and, if the reaction is intense, collapse, cyanosis, chest and/or back pain and diffuse hemorrhage Note: If any of above signs appear in a transfusion reaction, or if the temperature rises 1ºC, the transfusion must be stopped; most Pts survive if < 200 ml has been transfused in cases of red cell incompatibility-induced transfusion reaction; over 50% die when 500 ml or more has been transfused; TF mortality is ± 1.13/105 transfusions Clinical Flank pain, fever, chills, bloody urine, rash, hypotension, vertigo, fainting Transfusion reactions Immune, non

-infectious transfusion reactions • Allergic Urticaria with immediate hypersensitivity • Anaphylaxis Spontaneous anti-IgA antibody formation, occurs in ± 1:30 of Pts with immunoglobulin A deficiency, which affects 1:600 of the general population–total frequency: 1/30 X 1/600 = 1/18,000 • Antibodies to red cell antigens, eg antibodies to ABH, Ii, MNSs, P1, HLA • Serum sickness Antibodies to donor's immunoglobulins and proteins Non-immune, non-infectious transfusion reactions • Air embolism A problem of historic interest that occurred when air vents were included in transfusion sets • Anticoagulant Citrate anticoagulant may cause tremors and EKG changes • Coagulation defects Depletion of factors VIII and V; this 'dilutional' effect requires massive transfusion of 10 + units before becoming significant • Cold blood In ultra-emergent situations, blood stored at 4º C may be tranfused prior to reaching body temperature at 37º C; warming a unit of blood from 4

 to 37º C requires 30 kcal/L of energy, consumed as glucose; cold blood slows metabolism, exacerbates lactic acidosis, ↓ available calcium, ↑ hemoglobin's affinity for O2 and causes K+ leakage, a major concern in cold hemoglobinuria • Hemolysis A phenomenon due to blood collection trauma, a clinically insignificant problem • Hyperammonemia and lactic acid Both molecules accumulate during packed red cell storage and when transfused, require hepatorenal clearance, of concern in Pts with hepatic or renal dysfunction, who should receive the freshest units possible • Hyperkalemia Hemolysis causes an ↑ of 1 mmol/L/day of potassium in a unit of stored blood, of concern in Pts with poor renal function, potentially causing arrhythmia • Iron overload Each unit of packed RBCs has 250 mg iron, potentially causing hemosiderosis in multi-transfused Pts Microaggregates Sludged debris in the pulmonary vasculature causing ARDS may be removed with micropore filters Pseudoreaction Transfusion reaction mimics, eg anxiety, anaphylaxis related to a drug being administered at the same time as the transfusion Infections transmitted by blood transfusion

 • Viruses B19, CMV, EBV, HAV, HBV, HCV, HDV, HEV, Creutzfeldt-Jakob disease, Colorado tick fever, tropical viruses–eg Rift Valley fever, Ebola, Lassa, dengue, HHV 6, HIV-1, HIV-2, HTLV-I, HTLV-II • Bacteria Transmission of bacterial infections from an infected donor is uncommon and includes brucellosis and syphilis in older reports; more recent reports include Lyme disease and Yersinia enterocolitica Note: Although virtually any bacteria could in theory be transmitted in blood, the usual cause is contamination during processing rather than transmission from an infected donor • Parasites Babesiosis, Leishmania donovani, L tropica, malaria, microfilariasis–Brugia malayi, Loa loa, Mansonella perstans, Mansonella ozzardi, Toxoplasma gondii, Trypanosoma cruzi an·a·phy·lax·is (an'ă-fi-lak'sis) The immediate, transient Type 1 immunologic (allergic) reaction characterized by contraction of smooth muscle and dilation of cap

illaries due to release of pharmacologically active substances (histamine, bradykinin, serotonin, and slow-reacting substance), classically initiated by the combination of antigen (allergen) with mast-cell-fixed, cytophilic antibody (chiefly IgE); the reaction can be initiated, also, by relatively large quantities of serum aggregates (antigen-antibody complexes, and others) that seemingly activate complement leading to production of anaphylatoxin, a reaction sometimes termed "aggregate anaphylaxis." [G.

ana, away from, back from, + phylaxis, protection] anaphylaxis A severe, often fatal, form of hypersensitivity allergic reaction most commonly provoked by drugs such as penicillin, intravenous iron or procainamide, but also brought on by allergy to foods, vaccines, insect bites or snake bites and contact with latex rubber. There is always a history of a previous reaction to the ALLERGEN . The effects are a drop in blood pressure (hypotension), local swelling of the skin (angio-oedema) and mucous membranes, narrowing of the air tubes (bronchi), itching, vomiting and abdominal pain. The sooner the onset after exposure to the allergen, the more severe the reaction. Anaphylactic shock is a serious, widespread allergic attack which may cause death by AIRWAY obstruction from swelling of the lining of the LARYNX . anaphylaxis a hypersensitive reaction that can occur after a second exposure to an ANTIGEN . Such anaphylactic ‘shock’ responses are varied, ranging from reddening and itching of the skin through to respiratory failure and death.

anaphylaxis a dramatic and dangerous reaction by the immune system, caused by release of inflammatory mediators (such as histamine) from mast cells on exposure to an allergen. Characterized by urticaria ('hives'), pruritus (itching), angio-oedema ('welts'), respiratory distress, vascular collapse and shock. anaphylaxis ; anaphylactic shock immediate, sudden, potentially life-threatening, immune-based reaction induced by exposure (contact, ingestion, inhalation, injection) to allergenic material (e.g.

latex, drugs [antibiotics, aspirin, local anaesthetics], certain foods [nuts, shellfish, dairy]) leading to release of histamine, bradykinin and serotonin, especially in atopic individuals; characterized by marked smooth-muscle contraction, capillary dilatation and tissue oedema, severe fall in blood pressure, urticaria, laryngeal stridor and breathing difficulties; leads to loss of consciousness, coma and even death; immediate treatment includes intramuscular administration of adrenaline (see epinephrine ), high-flow oxygen and intravenous administration of antihistamine, and intravenous fluid supplementation; patients who take beta-blockers may not respond to adrenaline when in anaphylaxis; those taking tricyclic antidepressants overreact to adrenaline and thus require lower doses of adrenaline an·a·phy·lax·is (an'ă-fi-lak'sis) An induced systemic or generalized sensitivity; at times the term anaphylaxis is used for anaphylactic shock. The physiologic manifestations reflect the biologic effects of these mediators. Cutaneous symptoms include pruritus, erythema, urticaria, and angioedema.

Respiratory compromise can come from laryngeal obstruction or bronchospasm. Cardiac effects include arrhythmia, hypotension, and shock. The reaction may be fatal if asphyxiation or cardiovascular collapse occurs. [G. ana, away from, back from, + phylaxis, protection] anaphylaxis (an´əfilak´sis), n a violent allergic reaction characterized by sudden collapse, shock, or respiratory and circulatory failure after injection of an allergen. anaphylaxis an unusual or exaggerated allergic reaction of an animal to foreign protein or other substances. Anaphylaxis is an immediate or antibody-mediated hypersensitivity reaction (type I) produced by the release of vasoactive agents such as histamine and serotonin. Release is a consequence of the binding of IgE antibodies to Fc receptors on the surface of particularly mast cells and basophils. Antigen binding to two adjacent IgE molecules causes perturbation of the cell membrane leading to the release of vasoactive substances. Anaphylaxis may be localized, usually cutaneous, or generalized. Called also anaphylactic shock.

Substances most likely to produce anaphylaxis include drugs, particularly antibiotics and local anesthetics; drugs prepared from animals, such as insulin, adrenocorticotropic hormone and enzymes; diagnostic agents, such as iodinated x-ray contrast media; biologicals used to provide immunity, such as vaccines, antitoxins and gamma globulin; protein foods; the venom of bees, wasps and hornets; and pollens and molds. See also hypersensitivity , anaphylactic . acquired anaphylaxis Allergic Reaction Glossary of Terms with Medical Definitions See the entire definition of Anaphylaxis Anesthesia: Loss of feeling or awareness, as when an anesthetic is administered before sur... See the entire definition of Anesthesia Antibody: An immunoglobulin, a specialized immune protein, produced because of the introdu... See the entire definition of Antibody Antigen: A substance that the immune system perceives as being foreign or dangerous. The b... See the entire definition of Antigen Antihistamines: Drugs that combat the histamine released during an allergic reaction by bl...

See the entire definition of Antihistamines Aspirin: Once the Bayer trademark for acetylsalicylic acid, now the common name for this a... See the entire definition of Aspirin Asthma: A common lung disorder in which inflammation causes the bronchi to swell and narro... See the entire definition of Asthma Atopic: A predisposition toward developing certain allergic hypersensitivity reactions. At... See the entire definition of Atopic Atopic dermatitis: A skin disease characterized by areas of severe itching, redness, scali... See the entire definition of Breathing Bumps: The raised area of a bump or bruise results from blood leaking from these injured b... See the entire definition of Bumps Cardiac: Having to do with the heart. Cell: The basic structural and functional unit of any living thing. Each cell is a small c... See the entire definition of Cell Chest: The area of the body located between the neck and the abdomen. The chest contains t... See the entire definition of Chest Chronic: In medicine, lasting a long time. A chronic condition is one that lasts 3 months ... See the entire definition of Chronic Chronic disease: A disease that persists for a long time. A chronic disease is one lasting...

See the entire definition of Congestion COPD: Chronic obstructive pulmonary disease. Any disorder that persistently obstructs bron... See the entire definition of COPD Corticosteroid: Any of the steroid hormones made by the outer portion (cortex) of the adre... See the entire definition of Corticosteroid Cough: A rapid expulsion of air from the lungs, typically in order to clear the lung airwa... See the entire definition of Cough Dander: Tiny scales shed from human or animal skin or hair. Dander floats in the air, sett... See the entire definition of Dander Decongestant: A drug that shrinks the swollen membranes in the nose, making it easier for ... See the entire definition of Decongestant Dermatitis: Inflammation of the skin, either due to an inherent skin defect, direct contac... See the entire definition of Dermatitis Dermatologist: A physician who specializes in the diagnosis and treatment of skin problems... See the entire definition of Dermatologist Diagnosis: 1 The nature of a disease; the identification of an illness. 2 A ... See the entire definition of Diagnosis Diarrhea: A common condition that involves unusually frequent and liquid bowel movements. ...

See the entire definition of Diarrhea Digestive system: The system of organs responsible for getting food into and out of the bo... See the entire definition of Dilation Discharge: 1.The flow of fluid from part of the body, such as from the nose or vag... See the entire definition of Discharge Dizziness: Painless head discomfort with many possible causes including disturbances of ... See the entire definition of Dizziness Drip: Short for intravenous drip, a device for administering a fluid drop-by-drop into a v... See the entire definition of Drip Ear: The hearing organ. There are three sections of the ear, according to the anatomy tex... See the entire definition of Ear Eczema (dermatitis): A particular type of inflammatory reaction of the skin in which there... See the entire definition of Eczema Emergency department: The department of a hospital responsible for the provision of medica... See the entire definition of ENT Epinephrine: Also known as adrenaline. A substance produced by the medulla inside of the a... See the entire definition of Epinephrine Epipen®: a brand name for an epinephrine auto-injector device used to manage potential...

See the entire definition of EpiPen Fatigue: A condition characterized by a lessened capacity for work and reduced efficiency ... See the entire definition of Fatigue Fever: Although a fever technically is any body temperature above the normal of 98.6 F (37... See the entire definition of Fever Fungi: Plural of fungus. See the entire definition of Gastrointestinal Gluten: A protein found in wheat or related grains and many foods that we eat. Gluten can ... See the entire definition of Gluten Hay fever: A seasonal allergy to airborne particles characterized by itchy eyes, runny nos... See the entire definition of Immunology Immunotherapy: Treatment to stimulate or restore the ability of the immune (defense) syst... See the entire definition of Immunotherapy Inflammation: A localized reaction that produces redness, warmth, swelling, and pain as a ... See the entire definition of Inflammation Iodine: An element in the diet that is essential for the manufacture of hormones by the th... See the entire definition of Iodine Itching: An uncomfortable sensation in the skin that feels as if something is crawling on ...

See the entire definition of Itching Lightheadedness: A feeling you are "going to faint." Lightheadedness is medically distinct... See the entire definition of Lightheadedness Lips: Aside from the lips of the mouth, there are two pairs of lips at the entrance to the... See the entire definition of Lips Low blood pressure: Any blood pressure that is below the normal expected for an individua... See the entire definition of Poisoning Pollen: Small, light, dry protein particles from trees, grasses, flowers, and weeds that m... See the entire definition of Pollen Potassium: The major positive ion (cation) found inside cells. The chemical notation for p... See the entire definition of Potassium Prescription: A physician's order for the preparation and administration of a drug or dev... See the entire definition of Prescription Probiotics: live microorganisms (usually bacteria) that are similar to beneficial microor... See the entire definition of Probiotics Prognosis: The forecast of the probable outcome or course of a disease; the patient's chan... See the entire definition of Prognosis Protein: One of the three nutrients used as energy sources (calories) by the body. Protein...

See the entire definition of Protein Pulmonary: Having to do with the lungs. Pulse: The rhythmic dilation of an artery that results from beating of the heart. Pulse is... See the entire definition of Pulse Radioallergosorbent test: An allergy test done on a sample of blood. The test is used to ... See the entire definition of Sweating Syndrome: A combination of symptoms and signs that together represent a disease process. Therapy: The treatment of disease. Therapy is synonymous with treatment. Throat: The throat is the anterior (front) portion of the neck beginning at the back of th... See the entire definition of Throat Tired: A feeling of a lessened capacity for work and reduced efficiency of accomplishment,... See the entire definition of Tired Tongue: A strong muscle that is anchored to the floor of the mouth. The tongue is covered ... See the entire definition of Tongue Trigger: Something that either sets off a disease in people who are genetically predispose... See the entire definition of Trigger Trimox: See: Amoxicillin. See the entire definition of Tubes Unconscious: 1. Interruption of awareness of oneself and one's surroundings, lack ...

See the entire definition of Unconscious Urticaria: Another name for hives. Raised, itchy areas of skin that are usually a sign of ... See the entire definition of Urticaria Vaccines: Microbial preparations of killed or modified microorganisms that can stimulate a... See the entire definition of Vaccines Viruses: Small living particles that can infect cells and change how the cells function. I... See the entire definition of Viruses Wheezing: A whistling noise in the chest during breathing. Wheezing occurs when the airway... See the entire definition of Wheezing White blood cell: One of the cells the body makes to help fight infections. There are seve... Anaphylaxis Guide: Causes, Symptoms and Treatment Options Q & A What Is It? Anaphylaxis is a severe, sometimes life-threatening, allergic reaction that occurs within minutes to several hours of exposure an allergy-causing substance (allergen). Anaphylaxis also is called anaphylactic shock. In an allergic reaction, the body's immune system responds to the presence of an allergen by releasing histamine and other body chemicals.

These chemicals cause the symptoms of allergies, which are usually mild but annoying, such as the runny nose of hay fever (allergic rhinitis) or the itchy rash of poison ivy. However, in some cases, the symptoms can be much worse and involve the entire body. Anaphylaxis is the most severe allergic reaction. In anaphylaxis, these immune chemicals cause serious skin symptoms, such as hives and swelling, as well as severe breathing problems, such as swelling in the throat, narrowing of the lower airways and wheezing). The chemicals also cause blood vessels to widen dramatically, which leads to a rapid, severe drop in blood pressure (shock). Anaphylaxis is a life-threatening medical emergency. Although the specific allergen that triggers anaphylaxis may be different for each patient, it often can be traced to one of the following sources: Foods — Especially eggs, seafood, tree nuts, grains, milk and peanuts Drugs — Especially an antibiotic from the penicillin or cephalosporin group, a "sulfa" antibiotic, or ibuprofen and other non-steroidal anti-inflammatory pain medicines (NSAIDs).

Insect stings — From bees, yellow jackets, paper wasps, hornets or fire ants Injected anesthetics — Procaine, lidocaine Dyes — Used in diagnostic X-rays and scans Industrial chemicals — Latex and rubber products used by health care workers Allergy shots (immunotherapy) Symptoms Symptoms of anaphylaxis usually occur within seconds to minutes of exposure to the allergen, but symptoms can be delayed for several hours. For some people, symptoms do not always show up after an exposure, but are triggered if an exposure is followed by vigorous exercise. Symptoms range from mild to very severe.

These symptoms can include: Rapid pulse, sweating, dizziness, fainting, unconsciousness Wheezing, chest tightness, difficulty breathing, coughing Itchy hives, which may blend together to form larger areas of skin swelling Swelling of the lips, tongue or eyes Nausea, vomiting, abdominal cramps, diarrhea Paleness, bluish skin color Throat swelling, with a feeling of throat tightness, a lump in the throat, hoarseness or obstructed air flow Diagnosis The doctor will ask about the patient's allergy history and about his or her exposure to any of the common allergens that trigger anaphylaxis. It is very important for the doctor to know if the patient's symptoms started soon after exposure to an allergen, for instance after eating nuts, after a bee sting or after taking an antibiotic. Because the patient may be too sick to provide this information, a family member, friend, co-worker or school nurse will need to help. People with a history of severe allergic reactions should consider wearing a medical alert identification necklace or bracelet to save valuable time in identifying the problem. The doctor usually can diagnose anaphylaxis based on the patient's history and the results of a physical examination.

Expected Duration With early and appropriate treatment, cases of anaphylaxis can improve quickly within a few hours. If a person has already developed the more serious symptoms and dangerous conditions, it may take a few days to fully recover after treatment. If untreated, anaphylaxis can cause death within minutes to hours. Prevention You can prevent anaphylaxis by avoiding the allergens that trigger your symptoms. For example, people with food allergies should always check the list of ingredients on food labels, and they should always ask the waiter or waitress to check with the chef about food ingredients before eating at a restaurant. If you are allergic to bee stings, you should limit gardening and lawn mowing, and you should not wear perfumes, hair sprays or bright clothing that attracts insects. People with a history of anaphylaxis should wear a medical identification bracelet or necklace to alert others in the event of another reaction. In addition, ask your doctor if you should carry a pre-loaded syringe of epinephrine (adrenaline), a medicine used to treat anaphylaxis.

At the first sign of symptoms, you or a helper (family member, co-worker, school nurse) would inject the pre-loaded epinephrine to treat your allergic reaction until you reach medical attention. Allergy shots, also called immunotherapy, are used to gradually change the type of reaction that a person has after an insect sting. Allergy shots cause the immune system to react by producing varieties of antibodies and cells that do not cause dangerous symptoms, instead of producing antibodies and chemicals that result in allergy symptoms. On rare occasions, allergy shots also can be used to prevent certain medication allergies. Allergy shots are not used to treat food allergies, because the shots themselves are too likely to cause anaphylaxis. However, oral (swallowed) immunotherapy using extraordinarily diluted samples of peanut is a new treatment for peanut allergy. The results of treatment so far suggest this therapy will be effective and appears to be relatively safe. Treatment Symptoms of anaphylaxis usually require treatment with epinephrine , by injection. People who have had anaphylaxis can carry a pre-loaded syringe containing epinephrine .

This is the most important treatment for anaphylaxis symptoms, because it can help to prevent a blocked airway from throat swelling, which can otherwise result in suffocation. Symptoms can also be improved with antihistamines, anti-acid medicines known as "H2 blockers," and corticosteroids such as prednisone . It is important for a doctor to see you right away for allergy reactions that are severe, and for all reactions that are treated with epinephrine. Low blood pressure may need treatment with intravenous fluids or with medication to support blood pressure. When To Call A Professional Call for emergency assistance immediately whenever you have or a person you are assisting has symptoms of anaphylaxis. If you have a history of severe allergic reaction and have not mentioned this to your doctor, schedule an appointment soon. He or she can review your history and help you take the necessary precautions to avoid future problems. Prognosis With prompt, appropriate treatment, most patients who have had a severe allergic reaction can recover completely. Unfortunately, even with treatment, some people die from anaphylaxis. A person who has had anaphylaxis is at risk of future severe reactions if he or she is exposed again to the same allergen.

Learn more about Anaphylaxis Overview of Allergic Reactions - Immune Disorders - Merck Manuals Consumer Version Overview of Allergic Reactions Allergic Reactions and Other Hypersensitivity Disorders Overview of Allergic Reactions Year-Round Allergies Allergic reactions (hypersensitivity reactions) are inappropriate responses of the immune system to a normally harmless substance. Usually, allergies make the eyes water and itch, the nose run, the skin itch, rashes develop, and people sneeze. Some symptoms, called anaphylactic reactions, are life threatening. Symptoms suggest the diagnosis, and skin tests can help identify the substance that triggers the allergy. People who have had severe reactions should always carry a self-injecting syringe of epinephrine and antihistamine pills. Avoiding the trigger is best, but if it is impossible, allergy shots can sometimes desensitize the person. Severe reactions require emergency treatment in the hospital. Normally, the immune system —which includes antibodies, white blood cells, mast cells, complement proteins, and other substances—defends the body against foreign substances (called antigens).

However, in susceptible people, the immune system can overreact when exposed to certain substances (allergens) in the environment, foods, or drugs, which are harmless in most people. The result is an allergic reaction. Some people are allergic to only one substance. Others are allergic to many. About one third of the people in the United States have an allergy. Allergens may cause an allergic reaction when they land on the skin or in the eye or are inhaled, eaten, or injected. An allergic reaction can occur in several ways: As part of a seasonal allergy (such as hay fever), caused by exposure to such substances as tree, grass, or ragweed pollens Triggered by taking a drug ( drug allergy ) Triggered by eating certain foods ( food allergy ) Triggered by breathing in dust, animal dander, or molds ( year-round allergy ) Triggered by touching certain substances (such as latex) Triggered by insect bites or stings (as occurs in anaphylactic reactions and angioedema ) In many allergic reactions, the immune system, when first exposed to an allergen, produces a type of antibody called immunoglobulin E (IgE) .

IgE binds to a type of white blood cell called basophils in the bloodstream and to a similar type of cell called mast cells in the tissues. The first exposure may make people sensitive to the allergen but does not cause symptoms. When sensitized people subsequently encounter the allergen, the basophils and mast cells with IgE on their surface release substances (such as histamine, prostaglandins, and leukotrienes) that cause swelling or inflammation in the surrounding tissues. Such substances begin a cascade of reactions that continue to irritate and harm tissues. These reactions range from mild to severe. What Is Latex Sensitivity? Latex is a fluid that comes from the rubber tree. It is used to make rubber products, including some rubber gloves, condoms, and medical equipment such as catheters, breathing tubes, enema tips, and dental dams. Latex can trigger allergic reactions, including hives, rashes, and even severe and potentially life-threatening allergic reactions called anaphylactic reactions. However, the dry, irritated skin that many people develop after wearing latex gloves is usually the result of irritation and not an allergic reaction to latex.

In the 1980s, health care workers were encouraged to use latex gloves whenever touching patients to prevent the spread of infections. Since then, latex sensitivity has become more and more common among health care workers. Also, people may be at risk of becoming sensitive to latex if they Have had several surgical procedures Must use a catheter to help with urination Work in plants that manufacture or distribute latex products For unknown reasons, people who are sensitive to latex are often allergic to bananas and sometimes other foods such as kiwi, papaya, avocados, chestnuts, potatoes, tomatoes, and apricots. Doctors may suspect latex sensitivity based on symptoms and the person's description of when symptoms occur, especially if the person is a health care worker. Blood or skin tests are sometimes done to confirm the diagnosis. People who are sensitive to latex should avoid it. For example, health care workers can use gloves and other products that are latex-free. Most health care institutions provide them. Causes Genetic and environmental factors work together to contribute to the development of allergies. Genes are thought to be involved because specific mutations are common among people with allergies and because allergies tend to run in families. Environmental factors also increase the risk of developing allergies.

These factors include the following: Repeated exposure to foreign substances (allergens) Diet Pollutants (such as tobacco smoke and exhaust fumes) On the other hand, exposure to various bacteria and viruses during childhood may strengthen the immune system, help the immune system learn how to respond to allergens, and thus help prevent allergies from developing. An environment that limits a child's exposure to bacteria and viruses—commonly thought of as a good thing—may make allergies more likely to develop. Exposure to microorganisms is limited in families with fewer children and cleaner indoor environments and by the early use of antibiotics. Allergens that most commonly trigger allergic reactions include House dust mite droppings Anaphylaxis Symptoms Anaphylaxis Symptoms Home What is Anaphylaxis? Anaphylaxis Symptoms Be the first to know! Sign up now to stay in the know with the latest news and exclusive offers delivered right to your inbox! Sign up now Intended for US residents only. For more information, please review our Privacy Policy. Do you know the signs and symptoms of anaphylaxis? Anaphylaxis (an-a-fi-lax-is) is the medical term for a potentially life-threatening allergic reaction.

It can occur within minutes after exposure to an allergen. That’s why it’s important to know what symptoms to look for: Mouth Swelling of lips and/or tongue Lungs Cramps Why is it important to know these signs and symptoms? Anaphylaxis is unpredictable—a mild allergic reaction one time can be life-threatening or severe the next. For example, someone who has a peanut allergy may accidentally eat a peanut and feel tingling lips and watery eyes that eventually go away. However, if the same person is accidentally exposed to a peanut on a different occasion, it could cause difficulty breathing, weak pulse, shortness of breath, fainting and hives that may quickly become life-threatening. Both are instances of anaphylaxis, but the severity, progression, symptoms and duration of the symptoms are inconsistent and unpredictable. Is shock (sometimes called anaphylactic shock) a symptom of anaphylaxis? Shock is just one of the many possible symptoms of anaphylaxis. It occurs when there is inadequate blood flow to critical organs of the body during anaphylaxis. However, shock may not be one of the symptoms a person experiences during anaphylaxis.

More than half of all patients in a 10-year study showed no signs of shock during anaphylaxis. That’s why the term anaphylaxis is not interchangeable with the term anaphylactic shock—the first term encompasses all possible symptoms of a life-threatening allergic reaction. Think you might be at increased risk for a life-threatening allergic reaction? Use our Self-Assessment Tool to help start the conversation with your healthcare professional. Vigilance is essential Because of this unpredictability, it’s crucial for parents and caregivers of children living with potentially life-threatening, or severe, allergies—as well as adults with severe allergies—to be vigilant about any type of allergic reaction ranging from mild to severe. Talk to a healthcare professional about how to identify the signs and symptoms of a life-threatening allergic reaction (anaphylaxis). When to use EpiPen® (epinephrine injection, USP) or EpiPen Jr® (epinephrine injection, USP) Auto-Injector? The drug in EpiPen® and EpiPen Jr® Auto-Injectors is epinephrine. It’s important to administer epinephrine at the first signs of anaphylaxis.

According to National Food Allergy Guidelines, epinephrine is the first-line treatment for life-threatening allergic reactions. A delay in administering epinephrine can be life-threatening. If you, your child or someone you're caring for shows signs or symptoms of a life-threatening allergic reaction, administer EpiPen® or EpiPen Jr® Auto-Injector immediately as prescribed and seek emergency medical care. For a more comprehensive look at anaphylaxis, check out our Signs and Symptoms Guide. Serious Allergic Reactions (Anaphylaxis) Serious Allergic Reactions (Anaphylaxis) Reacción alérgica grave (anafilaxia) Someone with certain types of allergies (like food allergies) can be at risk for a sudden, potentially life-threatening allergic reaction called anaphylaxis. If it happens to you, it can seem scary: You may start out feeling as if you are having a mild allergic reaction, then faint, have trouble breathing, or feel like your throat is closing, for example. But, with the right action, anaphylaxis can be treated. Anaphylaxis isn't common. But some people with allergies are more at risk than others.

People with allergies to insect bites and stings, foods, or certain medications are most at risk for anaphylaxis. So if you have allergies (or a friend or family member does), it's good to know about anaphylaxis and be prepared. Signs of Anaphylaxis How can people tell if an allergic reaction is an emergency? One clue is if it happens in two or more of these body systems: skin respiratory system cardiovascular system For example, someone may feel tightness or closing in the throat (respiratory system) together with a fast heartbeat (cardiovascular system). Here are the most common signs that a person who has been exposed to an allergen (anything that can cause an allergic reaction) might have anaphylaxis: difficulty breathing continue What to Do Anaphylaxis requires immediate treatment. It can get worse very quickly. If you have a known allergy and start to have a reaction, use your epinephrine injector (if you have one) and call 911, or immediately go to the nearest emergency room. Let friends know about your allergy so they can help you, if necessary. What Is Epinephrine?

When someone has anaphylaxis, the body releases allergic chemicals into the blood. These chemicals cause the types of problems mentioned earlier — like a fast heartbeat and trouble speaking. To work against this reaction, doctors usually want people with life-threatening allergies to carry a medication called epinephrine. Epinephrine works by relieving the symptoms of anaphylaxis. For example, it decreases swelling and raises blood pressure. Epinephrine has to get into the bloodstream as fast as possible in an emergency. So it needs to be given as an injection. This isn't as scary as it sounds. There's no big needle and plunger involved. Instead, scientists have developed an auto injector about the size of a large pen that's easy to carry and use. If you need to carry an epinephrine auto injector, your doctor will write you a prescription and show you how to use it. When to Use Epinephrine If your doctor prescribes an epinephrine auto injector, carry it with you at all times. With anaphylaxis, seconds count. Epinephrine can be a lifesaver.

If you start to have difficulty breathing, tightness in your throat, feel faint, or if you have allergic symptoms in more than one of the body systems mentioned earlier, give yourself epinephrine right away. Don't try to use your inhaler and wait to see what happens. Go straight for the epinephrine injector! That's especially true if you have food allergies and also have asthma. After using an epinephrine auto injector, go to a hospital emergency room right away. Sometimes a person has a second wave of symptoms (called a biphasic reaction). The hospital will observe you for at least 4 hours to be sure you are OK and give you additional treatment, if needed. Serious allergies can sound scary, but they are treatable. So if you have an auto injector, carry it with you always. That tiny pinprick can mean the difference between life and death!

Question: What medical term is used for an extreme life-threatening allergic reaction?
Answer: Anaphylaxis