May occur together or separately. Urticaria involves only the superficial dermis and presents as pruritic, circumscribed wheals with raised serpiginous borders and blanched centers. Angioedema involves deeper layers of skin and may include subcutaneous tissue; it is marked by dramatic swelling with more pain than pruritus. Recurrent episodes of urticaria and/or angioedema of <6 weeks duration are considered acute, whereas attacks persisting beyond this period are chronic.

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