Treatment of Anaphylaxis
Publication Date: February 2, 2022
Last Updated: January 26, 2023
Summary of Recommendations
Epinephrine is the essential, primary treatment that should be given once anaphylaxis has been diagnosed. (1A)
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If possible, separating the patient from the inciting allergen is prudent, but vomiting should not be induced to eliminate a food-based allergen. (1C)
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Given its effectiveness and rapid administration, IM epinephrine is the first-line treatment for anaphylaxis. The preferred injection site is the anterior lateral thigh, followed by the deltoid. (1B)
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Over-the-counter, metered-dose inhalers of epinephrine have not been found to be a practical or effective treatment for anaphylaxis. (1B)
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An organization’s choice of an epinephrine delivery device depends on considerations of cost, operator training, and safety for both patient and first responder. (1C)
Autoinjectors may be less prone to dosage error, but they require periodic training to use correctly and avoid injury. With regular training, the ampule or vial and syringe method has been safely used for decades in field conditions by NOLS and OB. A third option involves prefilled or fixed-dose syringes with epinephrine.
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Standard IM doses of epinephrine may be repeated every 5 to 15 min for an inadequate response to initial anaphylaxis treatment or hours later for a biphasic reaction. (1B)
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In general, an EAI with a 16 mm needle delivers an effective dose of medication in adult patients (1B), although obese patients may benefit from a longer needle. (2B)
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For manual syringes, a 16 mm needle delivers an effective IM dose in fit adolescents and young adults, though a 25 mm or longer needle should be considered in large adults or obese patients. (1C)
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During manufacturing shortages, US government agencies have approved the use of epinephrine for up to 9 mo past the expiration date. This extension provides a potential rationale, but not regulatory approval, for the use of recently expired epinephrine in shortages associated with austere or disaster conditions. (2C)
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In addition, uncontaminated epinephrine may retain its potency despite short excursions to high or low temperatures as may occur in the field. (2B)
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Absolute contraindications to epinephrine in anaphylaxis are lacking; however, IV administration carries additional risks and generally requires advanced medical expertise and monitoring. (1C)
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Proper limb immobilization and injection technique may decrease the risk of EAI-associated injuries, especially in children. For inadvertent digital injection of epinephrine, treatment options include warm compresses, topical nitroglycerin, and, in severe cases, local phentolamine injection. (1C)
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Antihistamines may help blunt the overall severity of anaphylaxis when given early with epinephrine. (1C)
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Non-sedating antihistamines may be preferred in the field to help keep the patient alert and potentially able to walk. (2B)
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The addition of an H2 antihistamine to an H1 antihistamine has improved outcomes in allergic reactions and may be beneficial in anaphylaxis, but the exact incremental benefit is unknown. (2B)
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Inhaled β-agonists may be administered as adjunctive treatment for wheezing, especially in a person with a history of asthma. (1C)
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Evidence of benefit for corticosteroids in anaphylaxis is inconsistent; however, pending conclusive evidence, continued empiric use is reasonable given the potential for benefit paired with a low side-effect profile. (1C)
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In particular, corticosteroids should be given for anaphylaxis with a respiratory component in asthmatic patients. (1C)
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In the field, medical evacuation is generally recommended after treatment of anaphylaxis. (2C)
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The actual decision to evacuate, however, may be influenced by case-specific factors, such as geography, weather, field capabilities, and patient characteristics and response to treatment. These factors also may influence the timing and method of evacuation. For austere or disaster conditions, off-label techniques for disassembling an EAI after IM administration to obtain another epinephrine dose are available and should be considered an inherently risky but potentially life saving measure when no other source is available. (2C)
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Epinephrine may be given every 5 to 15 min IM to treat refractory anaphylaxis, along with the secondary treatments of antihistamines and corticosteroids, as well as inhaled β agonists for patients with bronchospasm . (1C)
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For hypotension after epinephrine administration, IV crystalloids may be given with additional doses of IM epinephrine. (1C)
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For persistent hypotension, IV epinephrine or an alternative vasopressor may be considered, in addition to standard critical-care measures. (1C)
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For patients on long-term β blocker medication with refractory hypotension, glucagon is an option. (2C)
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The length of observation after treatment of anaphylaxis depends on the severity of the initial reaction and risk factors for a biphasic reaction. (1C)
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In patients with nonsevere reactions, a prompt response to treatment, and low risk for a biphasic reaction, observation for 1 h may be sufficient. (2B)
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Patients with more severe presentations, significant comorbidities, or requiring multiple doses of epinephrine may benefit from a minimum observation period of 6 h, or 12 to 24 h for presentations that involve cardiovascular compromise and hypotension. (2B)
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Before discharge from a medical center, patients should receive an epinephrine prescription and be advised to follow up for allergy testing and consideration of immunotherapy. (1C)
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Desensitization protocols to Hymenoptera venom and peanuts are available and should be considered in patients with prior anaphylactic reactions to these antigens. (1B)
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Hypersensitivity Reactions
Having trouble viewing table?
| Reaction type | Type I | Type II | Type III | Type IV |
| Name | IgE-mediated hypersensitivity | IgG-mediated cytotoxic hypersensitivity | Immune complex–mediated hypersensitivity | Cell-mediated hypersensitivity |
| Mechanism | IgE antibodies activate mast cells | IgG antibodies activate T cells and complement | Antigen–antibody complexes activate complement and neutrophils | Antigens activate T cells and macrophages |
| Onset | Immediate (within minutes) | Intermediate (minutes to hours) | Intermediate (hours) | Delayed (48–72 h) |
| Clinical example | Anaphylaxis | Blood transfusion reaction | Serum sickness | Contact dermatitis, poison ivy |
Recommendation Grading
Overview
Title
Treatment of Anaphylaxis
Authoring Organization
Wilderness Medical Society
Publication Month/Year
February 2, 2022
Last Updated Month/Year
February 12, 2024
Document Type
Guideline
Country of Publication
US
Inclusion Criteria
Male, Female, Adolescent, Adult, Child, Infant, Older adult
Health Care Settings
Emergency care
Intended Users
Paramedic emt, nurse, nurse practitioner, physician, physician assistant
Scope
Management, Prevention
Diseases/Conditions (MeSH)
D000707 - Anaphylaxis
Keywords
anaphylaxis, wilderness medicine
Source Citation
Gaudio FG, Johnson DE, DiLorenzo K, Anderson A, Musi M, Schimelpfenig T, Leemon D, Blair-Smith C, Lemery J. Wilderness Medical Society Clinical Practice Guidelines on Anaphylaxis. Wilderness Environ Med. 2022 Mar;33(1):75-91. doi: 10.1016/j.wem.2021.11.009. Epub 2022 Feb 2. PMID: 35120856.