[Myositis and rhabdomyolysis with influenza infection]

Myositis and rhabdomyolysis with influenza are rare, but sometimes serious complications. Patients with myositis more commonly have influenza B infection than influenza A. On the other hand, rhabdomyolysis are more frequently recognized in patients with influenza A infection than those with influenza B. Upper respiratory symptoms usually precede myositis, while rhabdomyolysis occurs simultaneously or shortly after the respiratory symptoms. Creatine kinase levels are elevated in myositis mildly and in rhabdomyolysis markedly. Influenza myositis improve spontaneously within 6 weeks, but influenza rhabdomyolysis sometimes induce renal failure with fatal outcome. Although the true incidence of myositis and rhabdomyolysis in the influenza infection remains unknown, careful medical care is necessary when patients have muscle pain and weakness.