What is the initial approach to managing urticaria associated with a viral illness?

Management of Urticaria Associated with Viral Illness

The initial approach to managing urticaria associated with a viral illness should focus on non-sedating H1 antihistamines as first-line therapy, which can be increased up to four times the standard dose if necessary for symptom control. 1, 2

Initial Assessment and Treatment

First-Line Treatment

• Non-sedating second-generation H1 antihistamines:
  • Options include cetirizine, desloratadine, fexofenadine, levocetirizine, loratadine, or mizolastine 1
  • Start with standard dosing once daily (except acrivastine which is taken three times daily)
  • If inadequate response, dose can be increased up to four times the standard dose 1, 2
  • Example: Cetirizine 10 mg daily, can be increased to 40 mg daily if needed

Supportive Measures

• Cooling antipruritic lotions such as calamine or 1% menthol in aqueous cream for symptomatic relief 1
• Avoid aggravating factors:
  • NSAIDs (can worsen urticaria, especially in aspirin-sensitive patients)
  • Alcohol
  • Overheating
  • Stress 1, 3

Treatment Algorithm for Persistent Symptoms

If Initial Treatment Is Insufficient:

1. Increase dose of non-sedating H1 antihistamine up to four times the standard dose 1, 2
2. Add combination therapy:
   • H2 antihistamines (e.g., famotidine) in addition to H1 antihistamines 1
   • Consider adding a sedating antihistamine at night for sleep disturbance 1
   • Leukotriene receptor antagonists (e.g., montelukast) may be beneficial in some cases 1, 4

For Severe Acute Urticaria:

• Short course of oral corticosteroids may be considered for severe acute urticaria or angioedema affecting the mouth 1, 2
• However, two out of three RCTs showed that adding corticosteroids to antihistamines did not improve symptoms compared to antihistamines alone 5

Special Considerations for Viral-Associated Urticaria

• Viral-associated urticaria is often self-limiting and typically resolves as the viral infection clears 4
• Post-infectious urticaria is one of the most common causes of new-onset urticaria in children and adults 3
• 50% of patients with acute urticaria will have resolution within 6 months 1

Management of Urticarial Reactions

For Mild Reactions (Pruritus, Flushing, Urticaria):

• Monitor for at least 15 minutes
• Consider second-generation antihistamines (loratadine 10 mg or cetirizine 10 mg) 1

For Moderate to Severe Reactions:

• If angioedema develops, especially affecting the airway, immediate medical attention is required
• For severe reactions with hypotension or respiratory compromise, emergency services should be called 1

Common Pitfalls to Avoid

1. Overuse of systemic corticosteroids - These should be restricted to short courses for severe cases only, as they may cause morbidity without providing significant benefit in most cases 1, 3

2. Misdiagnosis as allergic reaction - Viral-associated urticaria is often mistakenly treated as an allergic reaction; IgE-mediated allergy is rarely the cause of new-onset urticaria 3

3. Unnecessary extensive testing - For acute urticaria, no investigations are required except where suggested by history 1, 2

4. Prescribing epinephrine unnecessarily - Epinephrine is not indicated for acute urticaria or angioedema unless there is strong suspicion of anaphylaxis 3

5. Overlooking potential drug triggers - Carefully evaluate if the patient is taking medications that could worsen urticaria, such as NSAIDs or codeine 1, 2

Most patients with viral-associated urticaria will respond well to antihistamines and supportive care, with symptoms resolving as the viral infection clears. The prognosis is generally good, with most cases being self-limited.