Epinephrine First and Early: Pathophysiology, Outcomes, and Emergency Department Disposition

A detailed understanding of epinephrine’s pharmacologic actions can help primary care clinicians prioritize its use and counsel patients more effectively. During anaphylaxis, widespread mast cell and basophil degranulation leads to vasodilation, capillary leak, bronchoconstriction, and mucosal edema, culminating in hypotension, respiratory compromise, and potential cardiovascular collapse. Epinephrine, via stimulation of α₁‑, β₁‑, and β₂‑adrenergic receptors, reverses peripheral vasodilation, improves blood pressure, relaxes bronchial smooth muscle, and attenuates cutaneous and systemic manifestations. Importantly, low concentrations of epinephrine reach mast cells early after administration, inhibiting further mediator release and effectively “turning off” the reaction at its source.

Clinically, this translates into rapid symptom improvement in most patients when epinephrine is given promptly, although a minority will require a second dose. Observational experience and cohort data both indicate that prompt epinephrine administration is associated with reduced risk of progression to severe anaphylaxis, fewer biphasic reactions, and lower rates of hospitalization. A critical implication for primary care is that delayed epinephrine—whether due to diagnostic uncertainty, overreliance on antihistamines, or fear of adverse effects—remains a major modifiable contributor to poor outcomes. Patient and caregiver education should explicitly address these barriers and frame epinephrine as a safe, first‑line, time‑sensitive intervention.

In this video segment, Schroer prompts Golden to review the mechanisms by which epinephrine counteracts anaphylaxis, followed by Lieberman’s description of the typically dramatic and rapid clinical response after intramuscular injection in office‑based allergy practice. The discussion then turns to the 2024 practice parameter’s more flexible stance on post‑epinephrine emergency department referral. Golden explains that, when epinephrine is administered early, the reaction is not severe, the patient improves and remains stable, and a second dose is available, it may be reasonable—after shared decision‑making—to observe at home rather than mandate an emergency department visit in all cases. Lieberman emphasizes delinking epinephrine use from an automatic emergency department requirement, advocating that patients be instructed to administer epinephrine whenever they are concerned and to base further care on their subsequent clinical status and comfort level.

Disclosures include Novartis Pharmaceuticals, Regeneron Pharmaceuticals, BioCryst, GlaxoSmithKline, Amgen, GENZYME Corporation, AstraZeneca Pharmaceuticals, and LEO Pharma for Schroer; Novartis Pharmaceuticals, ABBVIE, Genentech, Aquestive Therapeutics for Lieberman; and Phadia US and Genentech USA for Golden.

References:

1. Golden DBK, Wang J, Waserman S, et al. Anaphylaxis: A 2023 practice parameter update. Ann Allergy Asthma Immunol. 2024;132(2):124-176. doi:10.1016/j.anai.2023.09.015

2. ARS Pharma. ARS Pharmaceuticals Announces FDA Approval of neffy® 1 mg (epinephrine nasal spray) for Type I Allergic Reactions, Including Anaphylaxis, in Pediatric Patients Weighing 15 to < 30 Kilograms - ARS Pharmaceuticals. ARS Pharmaceuticals. Published March 5, 2025. Accessed February 20, 2026. https://ir.ars-pharma.com/news-releases/news-release-details/ars-pharmaceuticals-announces-fda-approval-neffyr-1-mg

3. Aquestive Therapeutics. Aquestive Therapeutics Announces FDA Issuance of Complete Response Letter for Anaphylm^TM - Aquestive Therapeutics. Aquestive Therapeutics. Published February 6, 2026. Accessed February 20, 2026. https://investors.aquestive.com/news-releases/news-release-details/aquestive-therapeutics-announces-fda-issuance-complete-response