Definition
Hives, medically known as urticaria, are raised, itchy welts on the skin, often with surrounding redness, resulting from transient leakage of plasma from small blood vessels into the skin. Lesions typically last less than 24 hours in the same spot but may recur in different areas.
Classification
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Acute urticaria
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Lasts less than 6 weeks
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Often due to allergic reactions, infections, medications, or foods
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Chronic urticaria
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Persists for 6 weeks or longer
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Often idiopathic or autoimmune in nature
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Physical urticaria
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Triggered by physical stimuli such as cold, heat, pressure, vibration, or sunlight
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Etiology and Triggers
Allergic triggers
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Foods: nuts, shellfish, eggs, milk
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Medications: penicillins, NSAIDs, aspirin, sulfonamides
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Insect stings and bites
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Latex
Non-allergic triggers
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Viral or bacterial infections
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Physical factors: temperature extremes, pressure, exercise
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Emotional stress
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Autoimmune conditions (autoantibodies activating mast cells)
Pathophysiology
Hives result from the activation of mast cells in the skin, leading to the release of histamine and other mediators. This causes:
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Vasodilation → redness
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Increased vascular permeability → swelling (wheal formation)
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Stimulation of sensory nerves → itching
Clinical Features
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Raised, well-circumscribed, edematous plaques (wheals)
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Often pale in the center with surrounding erythema
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Itching is intense and may be accompanied by burning sensation
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Lesions change shape, move around, and resolve without scarring
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Angioedema may occur in deeper tissues, leading to swelling of lips, eyelids, tongue, or airway
Diagnosis
Diagnosis is clinical, based on history and examination.
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Assess for possible triggers and recent exposures
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Rule out anaphylaxis if associated with systemic symptoms (e.g., difficulty breathing, hypotension)
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Laboratory tests are not routinely required unless chronic or atypical presentation
Management
General Measures
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Identify and avoid triggers
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Wear loose, light clothing
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Avoid excessive heat and alcohol, which can worsen symptoms
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Use gentle, fragrance-free skin care products
Pharmacological Treatment
1. Non-sedating H1 antihistamines – First-line therapy
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Cetirizine: Adults 10 mg orally once daily; children 6–12 years 5–10 mg once daily
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Loratadine: Adults 10 mg orally once daily; children 2–12 years 5–10 mg once daily
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Fexofenadine: Adults 120–180 mg orally once daily; children 6–12 years 30 mg twice daily
If symptoms persist, doses can be increased (up to 4 times the standard dose in chronic urticaria under medical supervision).
2. Sedating antihistamines – For nighttime relief if itching disrupts sleep
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Chlorphenamine: Adults 4 mg orally every 4–6 hours (max 24 mg/day)
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Diphenhydramine: Adults 25–50 mg orally every 4–6 hours
3. H2 receptor antagonists – May be added in refractory cases
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Famotidine: 20 mg orally twice daily
4. Leukotriene receptor antagonists – Useful in aspirin-sensitive or physical urticaria
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Montelukast: Adults 10 mg orally once daily in the evening
5. Corticosteroids – For severe acute urticaria with significant discomfort (short course only)
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Prednisolone: Adults 20–40 mg orally once daily for 3–5 days
6. Advanced therapy for chronic refractory urticaria
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Omalizumab (anti-IgE monoclonal antibody)
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Cyclosporine in selected severe autoimmune cases
Special Considerations – Anaphylaxis Risk
If hives are associated with:
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Swelling of tongue/lips
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Difficulty breathing
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Wheezing
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Dizziness or collapse
Treat as anaphylaxis:
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Adrenaline (epinephrine) IM into mid-outer thigh
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Adults: 0.3–0.5 mg (0.3–0.5 mL of 1:1000 solution)
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Children: 0.01 mg/kg (max 0.3 mg per dose)
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Call emergency services immediately
Prognosis
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Acute urticaria usually resolves within days to weeks once the trigger is removed
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Chronic urticaria can persist for months to years but is non-life-threatening in most cases
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Symptom control is achievable in the majority with antihistamines and trigger avoidance
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