What is viral myositis (inflammation of muscles caused by a virus)?

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Last updated: February 24, 2025View editorial policy

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From the Guidelines

Viral myositis is a condition where viral infections cause inflammation of the muscles, and its diagnosis and management should prioritize reducing morbidity, mortality, and improving quality of life. The management of viral myositis should focus on supportive care, symptom relief, and reducing inflammation.

  • Rest is crucial to avoid exacerbating the condition, and patients should avoid strenuous activities until symptoms improve.
  • For pain and inflammation, over-the-counter NSAIDs like ibuprofen (400-600mg every 6-8 hours) or naproxen (220-440mg every 12 hours) can be effective, as seen in various clinical guidelines 1.
  • Applying heat or cold packs to affected muscles can provide additional relief, and gentle stretching and range-of-motion exercises can help prevent stiffness without causing pain.
  • Adequate hydration is essential to prevent dehydration and support the body's recovery process. Most cases of viral myositis resolve within 2-4 weeks, but it is crucial to seek medical attention if symptoms worsen or if there are signs of severe muscle weakness, difficulty breathing, or dehydration. While antiviral medications are not typically used, a healthcare provider may recommend them in severe cases or for certain underlying conditions, as the primary goal is to support the body's immune system in fighting the viral infection while managing discomfort and preventing complications 1.

From the Research

Definition and Causes of Viral Myositis

  • Viral myositis is an uncommon condition associated with influenza virus infection, more common in children 2.
  • It is characterized by muscle pain and weakness with an isolated laboratory finding of elevated serum creatine kinase (CK) 3.
  • Infectious myositis can be caused by bacteria, viruses, parasites, or fungi, with viral causes presenting with diffuse muscle pain and flu-like symptoms 4.

Symptoms and Diagnosis

  • Symptoms of viral myositis include muscle pain or weakness, fever, and poor general state 4.
  • Diagnosis is made on clinical presentation, with imaging (computed tomography or magnetic resonance imaging) useful to detect which muscle is affected 4.
  • Elevated creatine kinase (CK) levels and myoglobinuria are useful in diagnosis and can indicate muscle damage 2, 5.
  • In some cases, no investigation is needed except in severe cases for which screening bloodwork and a urine myoglobin test can confirm the diagnosis and rule out complications 5.

Management and Treatment

  • Supportive measures, including rehydration and mitigation of fever, are often sufficient for managing viral myositis 2.
  • Antiviral therapy is not always required, and the prognosis is excellent with rest and analgesia 2, 5.
  • Treatment depends on the causative organism, and open surgical or imaging-guided drainage may be necessary in bacterial myositis 4.
  • Management of myositis should consider both the systemic complications and the comorbidities, which together determine the prognosis 6.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

[Infectious myositis].

La Revue de medecine interne, 2020

Research

Viral myositis in children.

Canadian family physician Medecin de famille canadien, 2017

Research

Strategy for suspected myositis.

Joint bone spine, 2019

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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