Fever and Acute Urticaria
Fever is not typical of acute urticaria, but when present, it signals important exceptions including autoinflammatory syndromes, urticarial vasculitis, or infectious causes that require further evaluation. 1
Typical Acute Urticaria Presentation
- Acute urticaria presents with itchy wheals lasting less than 6 weeks, with individual wheals resolving within 2-24 hours without systemic symptoms like fever. 1
- The diagnosis is primarily clinical, and ordinary urticaria does not cause fever. 2, 1
When Fever IS Present with Urticarial Lesions
Fever accompanying urticarial lesions indicates you are likely NOT dealing with simple acute urticaria. 1, 3 Consider these specific entities:
Autoinflammatory Syndromes
- Cryopyrin-associated periodic syndromes (CAPS) and Schnitzler syndrome characteristically present with spontaneous wheals, pyrexia (fever), and malaise. 1, 4
- The erythrocyte sedimentation rate is always elevated in autoinflammatory syndromes (unlike ordinary urticaria where it remains normal), providing a useful diagnostic clue. 2, 1
- These conditions show elevated inflammatory markers (CRP, serum amyloid A, leukocytosis) and do not respond to antihistamines. 4, 5
Urticarial Vasculitis
- Presents with painful lesions persisting >24 hours that resolve with bruising or hyperpigmentation, often accompanied by fever. 6, 4
- Requires histologic confirmation showing leukocytoclastic vasculitis. 6, 5
Infectious Causes
- Certain helminth infections (hookworm, Ascaris) can cause urticarial rash with fever during Loeffler's syndrome. 1
- Viral exanthems may present with urticarial-appearing lesions and fever. 6, 7
Clinical Pitfall to Avoid
Do not dismiss fever as part of urticaria. 6, 3 Fever with urticarial lesions warrants investigation for alternative diagnoses, particularly if lesions persist despite antihistamine therapy or if systemic symptoms are present. 6, 4