Introduction
These reactions resemble immediate hypersensitivity reactions but are not mediated by allergen-IgE interaction. Instead, direct mast cell activation occurs. Examples of pseudoallergic or “anaphylactoid” reactions include the now rare “red man syndrome”…

Introduction

Essentials of Diagnosis

• Fever, pruritus, and arthropathy.
• Reaction is delayed in onset, usually 7-10 days, when specific IgG antibodies are generated against the allergen.
• Immune complexes…

Clinical Findings

A. Symptoms and Signs
The development of symptoms and the nature of the reaction can suggest whether an immunologic process is responsible for symptoms. In previously sensitized individuals, immediate hypersensitivity…

Introduction

Essentials of Diagnosis

• Anaphylaxis is a systemic reaction with cutaneous symptoms, associated with dyspnea, visceral edema, and hypotension.
• Urticaria is characterized by large, irregularly shaped, pruritic, erythematous wheals.…

Introduction

Essentials of Diagnosis

• Seasonal or perennial occurrence of nasal pruritus, congestion, rhinorrhea, or paroxysms of sneezing, which may be associated with lower respiratory symptoms, eye erythema, pruritus, irritation, tearing, or eczematous…