From the Guidelines
Allergic reactions, particularly anaphylaxis, require immediate administration of epinephrine via an auto-injector, such as EpiPen, into the outer thigh, followed by calling emergency services, as emphasized by the 2020 practice parameter update on anaphylaxis 1.
Key Considerations for Allergic Reactions
- For mild allergic reactions, over-the-counter antihistamines like loratadine (Claritin) 10mg, cetirizine (Zyrtec) 10mg, or diphenhydramine (Benadryl) 25-50mg can be used, along with 1% hydrocortisone cream for skin reactions, as these are common first-line treatments for such symptoms.
- Severe allergic reactions, or anaphylaxis, are life-threatening and can be triggered by various exposures including foods, drugs, and insect venom, necessitating prompt recognition and treatment, as highlighted in the 2024 American Heart Association and American Red Cross guidelines for first aid 1.
- The mainstay of immediate treatment for anaphylaxis is intramuscular epinephrine, typically administered with an epinephrine autoinjector, which should be prescribed to individuals with a history of anaphylaxis for self-administration at the first sign of an anaphylactic reaction.
Prevention and Management Strategies
- Identifying and avoiding personal allergen triggers is the most effective prevention strategy, though complete avoidance isn't always possible, making access to proper medication essential, as noted in the context of anaphylaxis management 1.
- Individuals with known severe allergies should carry prescribed epinephrine auto-injectors at all times and wear medical alert identification to ensure prompt and appropriate treatment in case of an emergency.
- Allergic reactions occur because allergen exposure triggers mast cells and basophils to release histamine and other inflammatory chemicals, causing symptoms like swelling, itching, and breathing difficulties, underscoring the importance of rapid intervention in anaphylactic reactions, as discussed in the 2020 practice parameter update on anaphylaxis 1.
From the FDA Drug Label
Emergency treatment of allergic reactions (Type I), including anaphylaxis, which may result from allergic reactions to insect stings, biting insects, foods, drugs, sera, diagnostic testing substances and other allergens, as well as idiopathic anaphylaxis or exercise-induced anaphylaxis. Immediate hypersensitivity reactions may occur after administration of albuterol as demonstrated by rare cases of urticaria, angioedema, rash, bronchospasm, and oropharyngeal edema.
Allergic reactions can be treated with epinephrine (IM), which is used for emergency treatment of allergic reactions (Type I), including anaphylaxis.
- Signs and symptoms of anaphylaxis include:
- Flushing
- Apprehension
- Syncope
- Tachycardia
- Thready or unobtainable pulse associated with hypotension
- Convulsions
- Vomiting
- Diarrhea and abdominal cramps
- Involuntary voiding
- Airway swelling
- Laryngospasm
- Bronchospasm
- Pruritus
- Urticaria or angioedema
- Swelling of the eyelids, lips, and tongue Albuterol (INH) can cause immediate hypersensitivity reactions, including urticaria, angioedema, rash, bronchospasm, and oropharyngeal edema 2 3
From the Research
Definition and Symptoms of Allergic Reactions
- Allergic reactions are characterized by the sudden onset of acute allergic symptoms involving two or more organ systems 4
- Anaphylaxis is a potentially life-threatening, multisystem allergic reaction that can cause airway, breathing, or circulatory compromise 5
- Symptoms of anaphylaxis can range from mild urticaria and swelling to abdominal cramping, to respiratory collapse 6
- Urticaria, difficulty breathing, and mucosal swelling are the most common symptoms of anaphylaxis 7
Triggers of Allergic Reactions
- Most frequent elicitors of mast cell and primarily histamine dependent anaphylactic reactions are food, insect venom or drugs 4
- The most common triggers are medications, stinging insect venoms, and foods; however, unidentified triggers occur in up to one-fifth of cases 7
- Coexisting asthma, mast cell disorders, older age, underlying cardiovascular disease, peanut and tree nut allergy, and drug-induced reactions are associated with severe or fatal anaphylactic reactions 7
Treatment of Allergic Reactions
- Intramuscular epinephrine is the immediate treatment of all patients with anaphylaxis 5, 8
- Intravenous epinephrine should be used in patients in shock, either as a bolus or infusion, along with fluid resuscitation 5
- Airway obstruction must be recognized, and early intubation may be necessary 5
- Adjunct medications such as histamine H1 and H2 antagonists, corticosteroids, beta2 agonists, and glucagon may be considered after epinephrine administration 7
- Patients should be monitored for a biphasic reaction (i.e., recurrence of anaphylaxis without reexposure to the allergen) for four to 12 hours, depending on risk factors for severe anaphylaxis 7