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ULY CLINIC

20 Septemba 2025, 01:27:25

Urticaria (hives)

Urticaria is a vascular skin reaction characterized by transient, pruritic wheals — smooth, slightly raised lesions with sharply demarcated erythematous borders and pale centers. Wheals vary in size and shape and result from the local release of histamine and other vasoactive mediators, typically in a hypersensitivity reaction.

Acute urticaria: develops rapidly, usually from an identifiable trigger (foods, drugs, insect stings, contactants, inhalants, infections, environmental stimuli, or emotional stress). Lesions often resolve within 12–24 h but may recur in crops for several days.
Chronic urticaria: symptoms persist for >6 weeks, often idiopathic but sometimes autoimmune, infectious, or psychogenic.
Angioedema (“giant urticaria”): deeper swelling of subcutaneous tissue or mucosa, commonly involving lips, tongue, eyelids, extremities, or genitals; may threaten the airway.

Pathophysiology

Histamine release from mast cells/basophils → vasodilation, increased capillary permeability, and sensory nerve activation.
Other mediators: leukotrienes, prostaglandins, bradykinin (esp. in hereditary angioedema).
Chronic forms may involve autoantibodies against IgE or its receptor.
Physical urticarias (pressure, cold, heat, vibration, cholinergic) arise from non-IgE triggers of mast cell degranulation.

History and Physical Examination

History

Onset, duration, and evolution of wheals
Known allergies; relation to foods, medications, insect bites, latex, or occupational exposures
Temporal pattern: seasonal, diurnal, after exertion, or after bathing
Associated symptoms: pruritus, angioedema, respiratory or GI symptoms, syncope
Past medical history: atopy, autoimmune disease, chronic infections, thyroid disease, GI disorders
Drug and vaccine exposure (prescription, OTC, herbal)
Family history of angioedema or allergic disease

Physical Examination

Inspect skin for number, size, and distribution of wheals; look for angioedema of lips, tongue, eyelids, hands, or feet
Assess airway patency, voice changes, and swallowing difficulty
Auscultate lungs for wheeze or stridor
Take vital signs (BP, HR, RR, O₂ saturation)
Examine for systemic signs: fever, arthralgia, abdominal pain, hypotension

Medical causes of urticaria

Cause	Onset	Key Features	Associated Findings	Pathophysiology	Management
Anaphylaxis	Minutes–hours after exposure	Diffuse itchy wheals, flushing, angioedema	Dyspnea, wheeze, hypotension, abdominal cramps, vomiting	IgE-mediated mast cell degranulation → systemic histamine release	IM epinephrine, airway management, oxygen, IV fluids, H1/H2 blockers, corticosteroids
Hereditary angioedema	Recurrent, hours–days	Nonpruritic edema of face, extremities, bowel, or larynx	Abdominal pain, airway obstruction	C1-esterase inhibitor deficiency or dysfunction → bradykinin excess	C1 inhibitor concentrate, icatibant, airway protection
Allergic drug reaction	Variable	Wheals ± angioedema after penicillin, sulfonamides, aspirin, NSAIDs, opioids, vaccines, etc.	May include bronchospasm, fever, eosinophilia	Drug-induced histamine release or IgE hypersensitivity	Stop agent; give antihistamines ± corticosteroids
Food allergy	Acute (minutes–hours)	Hives after ingestion (nuts, shellfish, eggs, milk, soy, wheat)	Nausea, vomiting, angioedema, anaphylaxis	IgE reaction to food proteins	Eliminate food; epinephrine for severe reaction
Physical urticarias	Immediate after trigger	Lesions after cold, heat, exercise, vibration, sun, or pressure	Localized or generalized wheals	Non-IgE mast cell activation	Avoid trigger, antihistamines
Autoimmune / idiopathic	Chronic (>6 wk)	Daily/near-daily wheals ± angioedema	Often no systemic symptoms	Autoantibodies to IgE or its receptor	2nd-gen antihistamines, omalizumab, immunomodulators
Infections (e.g., viral, parasitic, Lyme)	Acute or recurrent	Wheals with fever, malaise, arthralgia	Depends on pathogen	Immune complex or cytokine release	Treat infection, symptomatic therapy

Other causes

IV radiographic contrast agents
Serum sickness or immune complex disease
Parasitic infestations (e.g., giardiasis, helminths)
Endocrine disorders (thyroid disease, rarely)
Malignancy (rare; e.g., urticarial vasculitis or paraneoplastic urticaria)

Emergency interventions

Rapidly assess airway, breathing, and circulation if there is angioedema or systemic reaction.
Administer IM epinephrine (0.3–0.5 mg) promptly for anaphylaxis.
Give high-flow oxygen, establish IV access, monitor cardiac rhythm.
Be prepared for intubation or cricothyrotomy if laryngeal edema develops.
Adjunctive therapy: H1 antihistamines, H2 blockers, corticosteroids, beta-agonists for bronchospasm.

Special considerations

Apply bland emollients or menthol/phenol lotions to soothe itching.
Prescribe non-sedating H1 antihistamines as first line; up-titrate dose if needed.
Short course of systemic corticosteroids for severe acute episodes (not for long-term use).
Consider leukotriene antagonists or omalizumab for refractory chronic urticaria.
Address psychological stressors if relevant.

Patient counseling

Educate about avoidance of known triggers (foods, drugs, insect stings, temperature extremes).
Recommend medical alert identification for patients at risk of anaphylaxis.
Demonstrate proper use of an epinephrine auto-injector and advise carrying it at all times if appropriate.
Encourage early medical attention for breathing or swallowing difficulty, or recurrent swelling.

Pediatric pointers

Acute papular urticaria: common after insect bites.
Urticaria pigmentosa (mastocytosis): rare, causes persistent brownish macules with whealing on rubbing (Darier sign).
Hereditary angioedema may present in older children or adolescents.
Evaluate for food allergies or viral infections in recurrent cases.

Geriatric pointers

Elderly may present atypically or with drug-related hives.
Polypharmacy increases risk of urticarial drug eruptions.
Monitor for antihistamine side effects (sedation, falls, confusion).

References

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Wolff K, Johnson RA. Fitzpatrick’s Color Atlas & Synopsis of Clinical Dermatology. 6th ed. New York (NY): McGraw Hill Medical; 2009.
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