Anaphylaxis & Unexpected Adverse Reactions to Therapies

Anaphylaxis is a rapid-onset, potentially fatal, systemic allergic reaction — common triggers include medications (particularly antibiotics like penicillin), certain foods, insect stings, latex, and contrast dye — presenting with a combination of skin findings (hives, flushing, itching), respiratory symptoms (throat tightness, wheezing, stridor from airway swelling), cardiovascular symptoms (hypotension, tachycardia progressing to shock), and gastrointestinal symptoms (nausea, vomiting, cramping), though not every system needs to be involved for the reaction to be anaphylaxis. Epinephrine (intramuscular, typically into the anterolateral thigh) is the first-line, priority treatment and should be given immediately once anaphylaxis is suspected — delaying epinephrine to first give an antihistamine or corticosteroid is a critical, frequently tested error, since those medications work too slowly to address the immediate, life-threatening airway and cardiovascular effects.