Are hives and erythematous (redness of the skin) exanthems common symptoms of influenza?

Hives and Erythematous Exanthems in Influenza

Hives and erythematous exanthems are not common manifestations of influenza infection, with cutaneous eruptions being rare complications rather than typical symptoms of the disease. 1, 2

Clinical Presentation of Influenza

Influenza is characterized by:

• Sudden onset of fever (38°C-40°C)
• Respiratory symptoms (cough in ~85% of cases)
• Systemic symptoms:
  • Myalgias (53%)
  • Headache (65%)
  • General malaise (80%)
  • Chills (70%)
  • Sore throat (50%)
  • Nasal congestion (60%)

The typical duration of illness is 3-7 days, although cough and malaise can persist for more than 2 weeks 2.

Cutaneous Manifestations in Influenza

Prevalence and Characteristics

• Skin manifestations are not listed among the typical symptoms of influenza in major clinical guidelines 1, 2
• When skin eruptions do occur with influenza, they typically present as:
  • Sparse superficial perivascular infiltrates
  • Mild spongiosis
  • Mild interface changes 3

Case Reports

Isolated case reports have documented:

• Erythematous rash appearing days after respiratory symptoms 4
• Diffuse exanthematous rash, most pronounced over the trunk 4
• Subconjunctival hemorrhage (related to coughing, not direct viral effect) 4

Allergic Reactions vs. Direct Viral Effects

It's important to distinguish between:

1. Direct viral effects: True influenza-associated exanthems are rare
2. Allergic reactions to influenza vaccine: These are well-documented but distinct from the disease itself

Vaccine-Related Reactions

• Immediate hypersensitivity reactions (including hives/urticaria) rarely occur after influenza vaccination 1
• When they do occur, they typically result from hypersensitivity to vaccine components, particularly residual egg protein 1
• VAERS data shows that rash is among the most frequently reported adverse events following influenza vaccination in children, but causality is difficult to establish 1

Diagnostic Considerations

When evaluating a patient with influenza-like illness and skin manifestations:

• Consider alternative diagnoses, including other viral exanthems or drug reactions 5
• Remember that the predictive value of clinical symptoms varies according to:
  • Circulation of other respiratory pathogens
  • Level of influenza activity in the community
  • Patient's age 2

Clinical Implications

• The presence of hives or erythematous exanthems in a patient with respiratory symptoms should prompt consideration of:

  • Drug reactions to medications taken for symptom relief
  • Co-infection with other pathogens
  • Rare cutaneous manifestation of influenza itself

• Documentation of influenza-associated skin eruptions may be useful for surveillance purposes, particularly during pandemic periods 3

In summary, while influenza primarily manifests as a respiratory illness with systemic symptoms, clinicians should be aware that rare cutaneous manifestations can occur, though they are not part of the typical clinical presentation.