What are the symptoms of an allergic reaction to the varicella vaccine?

Individuals who experience an allergic reaction to the varicella vaccine may develop symptoms ranging from mild to severe. Common manifestations include localized reactions such as redness, swelling, or tenderness at the injection site. Systemic allergic responses can involve urticaria (hives), pruritus (itching), angioedema (swelling of deeper skin layers, particularly around the eyes or lips), and respiratory symptoms such as wheezing, shortness of breath, or stridor. In rare but serious cases, anaphylaxis—a life-threatening, multisystem allergic reaction—may occur within minutes to hours after vaccination. Signs of anaphylaxis include hypotension, tachycardia, gastrointestinal distress (e.g., nausea, vomiting, abdominal cramps), and altered mental status. It is important to note that true IgE-mediated allergy to the varicella vaccine is exceedingly rare; most reported “allergic” reactions are non-allergic adverse events (e.g., fever, rash, or mild constitutional symptoms). A thorough evaluation—including detailed history, skin testing, and, when indicated, graded challenge or consultation with an allergist—is essential before concluding vaccine allergy and determining future immunization options.