From the Guidelines
Anaphylaxis exists on a spectrum from mild/moderate to life-threatening, with key differences in presentation and urgency, and the critical distinction lies in the involvement of respiratory and/or cardiovascular systems, which signals a medical emergency requiring immediate epinephrine administration. Mild to moderate anaphylaxis typically presents with localized symptoms such as skin reactions (hives, itching, flushing), mild swelling of lips or face, abdominal discomfort, nasal congestion, or sneezing, as noted in the 2020 practice parameter update 1. These symptoms, while uncomfortable, generally don't compromise vital functions. Life-threatening anaphylaxis, however, involves severe systemic manifestations including respiratory distress (stridor, wheezing, shortness of breath), significant drop in blood pressure, rapid or weak pulse, dizziness or confusion, and potentially loss of consciousness.
The key factors that differentiate mild to moderate signs and symptoms of anaphylaxis from life-threatening anaphylaxis include:
- Involvement of respiratory and/or cardiovascular systems
- Severity of symptoms, such as respiratory distress or significant drop in blood pressure
- Presence of systemic manifestations, such as dizziness or confusion
- Rapid progression of symptoms, which can quickly cascade to affect multiple organ systems
For life-threatening reactions, epinephrine (0.01 mg/kg of a 1:1000 solution, up to 0.5 mg in adults and 0.3 mg in children) should be injected intramuscularly into the anterolateral thigh without delay, followed by calling emergency services, as recommended in the 2020 practice parameter update 1 and further supported by the 2024 clinical practice guideline 1. Even mild symptoms should be monitored closely as they can rapidly progress to severe anaphylaxis. This progression occurs because anaphylaxis involves massive immune mediator release that can quickly cascade to affect multiple organ systems, with respiratory and cardiovascular compromise being particularly dangerous.
It is essential to note that antihistamines and glucocorticoids are often used as adjunctive therapy for anaphylaxis, but they should not be administered before, or in place of, epinephrine, as emphasized in the 2024 clinical practice guideline 1. Additionally, biphasic anaphylaxis, which is a recurrence of anaphylaxis after appropriate treatment, can occur, and patients at risk should be closely monitored, as suggested in the 2020 practice parameter update 1.
From the Research
Differentiation of Mild to Moderate and Life-Threatening Anaphylaxis
The differentiation between mild to moderate signs and symptoms of anaphylaxis and life-threatening anaphylaxis can be understood through the analysis of various symptoms and treatment approaches.
- Symptoms of anaphylaxis can manifest in different systems of the body, including cutaneous, respiratory, cardiovascular, and gastrointestinal systems 2.
- Life-threatening anaphylaxis is characterized by severe symptoms such as airway obstruction, breathing difficulties, and circulatory compromise, which can lead to death if not treated promptly 3, 4.
- The treatment approach for anaphylaxis involves the administration of epinephrine, which is the drug of choice, followed by supportive care and adjunct medications such as antihistamines and corticosteroids 2, 3, 4.
- The severity of anaphylaxis can be assessed based on the presence of certain risk factors, such as coexisting asthma, mast cell disorders, older age, underlying cardiovascular disease, and peanut and tree nut allergy 3.
- Patients with life-threatening anaphylaxis may require more aggressive treatment, including intravenous epinephrine, fluid resuscitation, and vasopressors, as well as close monitoring for potential biphasic reactions 4.
Factors Influencing Anaphylaxis Severity
Several factors can influence the severity of anaphylaxis, including:
- Delayed administration of epinephrine, which can increase the risk of fatal anaphylaxis 5.
- The use of antihistamines and corticosteroids, which may have a beneficial effect in some cases, but their role in anaphylaxis management is not well established 5.
- The presence of underlying medical conditions, such as asthma or cardiovascular disease, which can increase the risk of severe anaphylaxis 3.
- The severity of symptoms, such as airway obstruction or circulatory compromise, which can indicate life-threatening anaphylaxis 4.