Urticaria (hives)

Treatment of anaphylaxis

assess ABCs! call 911! first-line: epinephrine, IV fluids and oxygen

Angioedema

cause by same pathogenic mechanisms of urticaria, but pathology is in the deep dermis with subcutaneous swelling - commonly affects face or extremity (tongue, pharnyx, larynx, bowels -> hoarseness, dyspnea and GI symptoms) - may be painful or burning but NOT pruritic - may last several days

Diagnosis of urticaria

clinical dx IgE receptor Ab testin gis possible in chronic disease, but often does not change management most resolve in 1-3 years

Most common form of physical urticaria

dermatographism - sharply localized edema or wheal within seconds to minutes after skin has been rubbed

Treatment of urticaria

first line: 1st-gen. oral H1 antihistamines (ex. hydroxyzine or diphenhydramine) = sedating 2nd gen. H1 antihistamines (ex. loratidine, cetirizine or fexofenadine) = less sedating

Causes of chronic urticaria

idiopathic (>50%), physical causes (pressure, cold, heat, water, sunlight, vibration, exercise), autoimmune (IgE receptor Ab), infection, ingestion, medication cholinergic urticaria = triggered by heat or emotion

Causes of acute urticaria

idiopathic, post-infectious, food reaction, drug or infusion reaction note: detergents and common contact allergens are not triggers of urticaria (latex is an exception)

Pathophysiology or urticaria

mast cell degranulation -> histamine release -> binds H1 & H2 receptors -> arteriolar dilation, venous constriction, inc capillary permeability immunologic (antigen binds IgE on mast cell surface) or non-immunologic (via pharmacologic or physical mechanism)

Typical time course

most cases are acute (<6 weeks), but some are chronic (>6 weeks) ***indviduals papules last <12 hrs

Cardinal symptom of urticaria

pruritus

Anaphylaxis

serious allergic reaction that is rapid in onset and may cause death may have no skin lesions or may have angioedema and/or urticaria ask about: chest tightness, difficult breathing, hoarse voice, throat tightness, nausea, vomiting, abd pain, lightheadedness

Wheals

transient, circumscribed, elevated papules or plaques, often with erythematous borders and pale centers

What is urticaria (aka hives)?

vascular reaction of skin characterized by wheals surrounded by blanchable red halo or flare (erythema) indviduals papules last <12 hrs