What is the best approach to manage a patient with a symmetrical rash following urticaria (hives)?

Management of Symmetrical Rash Following Upper Respiratory Tract Infection

Start with second-generation non-sedating H1 antihistamines (cetirizine, fexofenadine, loratadine, or desloratadine) at standard doses as first-line therapy for this post-viral urticarial eruption. 1

Initial Clinical Assessment

The symmetrical distribution following an upper respiratory tract infection (URTI) strongly suggests post-viral urticaria, which is the most common presentation in both children and adults. 2 Key diagnostic features to confirm:

• Individual lesion duration: Ordinary urticaria wheals typically last 2-24 hours, while physical urticaria resolves in less than 1 hour (except delayed pressure urticaria). 3 If individual lesions persist beyond 24 hours, consider urticarial vasculitis and obtain a skin biopsy. 3
• Presence of angioedema: Patients with both wheals and angioedema have a poorer prognosis, with over 50% still having active disease after 5 years compared to 50% clearance by 6 months for wheals alone. 3
• Rule out urticaria multiforme: This benign post-viral hypersensitivity reaction presents with large polycyclic annular erythematous wheals and is commonly misdiagnosed as erythema multiforme. 4

First-Line Treatment Algorithm

Begin with a single second-generation H1 antihistamine at standard dosing for 2-4 weeks. 5 Options include:

• Cetirizine (preferred for rapid onset due to shortest time to maximum concentration) 5
• Fexofenadine
• Loratadine
• Desloratadine
• Levocetirizine 1

Trial at least two different non-sedating antihistamines if the first is ineffective, as individual responses and tolerance vary significantly. 1

Dose Escalation for Inadequate Response

If standard dosing provides inadequate control after 2-4 weeks, increase the antihistamine dose up to 4 times the standard dose when potential benefits outweigh risks. 1, 5 This is now common practice and well within safety parameters. 3

Add a first-generation antihistamine (hydroxyzine) at night for additional symptom control and to help with sleep if daytime antihistamines are insufficient. 3, 1

Adjunctive Therapies for Resistant Cases

If symptoms persist despite high-dose antihistamines:

• Add H2-antihistamines (ranitidine or famotidine) for resistant cases. 5
• Add leukotriene receptor antagonists (montelukast), particularly beneficial for aspirin-sensitive and autoimmune urticaria. 5

Role of Corticosteroids

Restrict oral corticosteroids to short courses (3-10 days maximum) only for severe acute urticaria or life-threatening angioedema (e.g., prednisolone 50 mg daily for 3 days in adults). 5 Avoid long-term corticosteroid use due to cumulative toxicity including hypertension, hyperglycemia, osteoporosis, and gastric complications. 3, 5

General Measures and Trigger Avoidance

Identify and minimize aggravating factors including:

• Overheating, stress, and alcohol 3, 1
• Avoid aspirin and NSAIDs, as they inhibit cyclooxygenase and can exacerbate urticaria. 3, 5
• Avoid ACE inhibitors if angioedema is present without wheals, and use cautiously when angioedema accompanies urticaria. 3, 5
• Avoid codeine and other drugs that can worsen urticaria. 3

Apply cooling antipruritic lotions (calamine or 1% menthol in aqueous cream) for symptomatic relief. 3, 5

Advanced Therapies for Refractory Cases

If symptoms remain uncontrolled despite optimized antihistamine therapy:

• Omalizumab 300 mg subcutaneously every 4 weeks is recommended for chronic spontaneous urticaria unresponsive to high-dose antihistamines, with up to 6 months allowed for response. 1
• Cyclosporine 4 mg/kg daily for up to 2 months is effective in approximately 65-70% of patients with severe autoimmune urticaria who fail omalizumab. 1, 5

Emergency Management

Administer intramuscular epinephrine 0.5 mL of 1:1000 (500 µg) immediately for severe urticaria with anaphylaxis or angioedema affecting the airway. 1, 5 Prescribe fixed-dose epinephrine pens (300 µg for adults) for patients at risk of life-threatening attacks. 1

Critical Pitfalls to Avoid

• Do not delay effective therapy while continuing ineffective high-dose antihistamines beyond 4-fold standard dosing. 1
• Do not perform extensive laboratory workups for acute post-viral urticaria unless clinical features suggest systemic disease (vasculitis, autoimmune conditions). 3, 2
• Do not use long-term corticosteroids for chronic urticaria management, as this leads to significant morbidity without addressing underlying disease. 3, 5

Prognosis

About 50% of patients with chronic urticaria presenting with wheals alone will be clear by 6 months, though acute post-viral urticaria typically resolves much sooner with appropriate antihistamine therapy. 3, 4