Management of Hives and Erythematous Exanthems in Influenza
For patients presenting with hives (urticaria) and erythematous exanthems associated with influenza, treatment should focus on symptomatic relief with antihistamines while continuing appropriate antiviral therapy for the underlying influenza infection.
Initial Assessment
When evaluating a patient with influenza who develops hives or erythematous exanthems, consider:
- Timing of rash in relation to symptom onset
- Whether the patient has received influenza vaccination recently
- Any new medications started (including over-the-counter)
- History of allergic reactions
- Severity of symptoms (presence of angioedema, respiratory distress)
Treatment Algorithm
1. Management of Urticaria/Hives
First-line treatment: H1 antihistamines 1
- Non-sedating second-generation antihistamines (preferred for daytime)
- Diphenhydramine may be used, particularly at night
For persistent symptoms: Consider adding H2 antihistamines (e.g., ranitidine) 1
For severe or widespread urticaria: Consider short-course systemic corticosteroids
- Prednisone 0.5-1mg/kg orally for 3-5 days 1
- Note: Corticosteroids should be avoided for simple urticaria due to potential morbidity without significant benefit
2. Antiviral Therapy for Influenza
Continue or initiate oseltamivir if within 48 hours of symptom onset 2
- Adults: 75 mg twice daily for 5 days
- Children dosing based on weight:
- <15 kg: 30 mg every 12 hours
- 15-23 kg: 45 mg every 12 hours
24 kg: 75 mg every 12 hours
For severely ill patients, consider antiviral treatment even if >48 hours from symptom onset 2
3. Antibiotics
- Not routinely indicated for uncomplicated influenza with skin manifestations
- Consider antibiotics only if evidence of bacterial superinfection 2
- If antibiotics are needed, preferred options include:
- Co-amoxiclav or a tetracycline (for adults)
- For children, co-amoxiclav is the drug of choice 2
Special Considerations
Egg Allergy Concerns
If the patient has received influenza vaccination and develops urticaria, consider possible egg allergy:
- For patients with history of only hives after egg exposure, future influenza vaccines can still be administered with appropriate precautions 2
- For patients with more severe reactions (angioedema, respiratory distress, lightheadedness), future vaccinations should be administered in a medical setting with supervision 2
Observation Guidelines
- Patients with isolated urticaria should be observed for 2 hours after resolution of symptoms 1
- Those with angioedema or signs of anaphylaxis require 4-6 hours of observation 1
- Monitor vital signs every 15-30 minutes in cases of severe reactions 1
Follow-up Recommendations
- Provide antihistamines for continuation during 3-5 days 1
- Advise patients to avoid alcohol and NSAIDs during recovery 1
- Consider referral to an allergist/immunologist for recurrent urticaria 1
When to Escalate Care
Immediate escalation to emergency care is required for:
- Signs of anaphylaxis (hypotension, respiratory distress)
- Extensive or rapidly progressing skin involvement
- Development of mucosal lesions or blistering (possible Stevens-Johnson syndrome)
- Signs of severe respiratory distress or hemodynamic instability
Prevention of Recurrence
- Document the reaction in the patient's medical record
- If reaction was related to influenza vaccination, consider alternative vaccine formulations for future seasons:
Remember that most cases of urticaria and exanthems associated with influenza are self-limiting once appropriate treatment is initiated, but careful monitoring for progression to more severe manifestations is essential.