What are the symptoms of Influenza A (influenza type A)?

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Last updated: April 3, 2025View editorial policy

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From the Guidelines

Influenza A symptoms typically include sudden onset of high fever, severe muscle aches, extreme fatigue, headache, dry cough, sore throat, runny or stuffy nose, and chills, as reported in the most recent study 1. These symptoms usually appear 1-4 days after exposure to the virus and can last for 5-7 days, though fatigue may persist for weeks. The severity ranges from mild to severe, with complications like pneumonia possible, particularly in high-risk groups such as the elderly, young children, pregnant women, and those with chronic health conditions. Some key points to consider about influenza A symptoms include:

  • Sudden onset of symptoms, including fever, chills, and headache 1
  • Respiratory symptoms, such as dry cough, sore throat, and runny or stuffy nose 1
  • Extreme fatigue and muscle aches, which can persist for weeks 1
  • Gastrointestinal symptoms, such as vomiting and diarrhea, especially in children 1
  • Potential for complications, such as pneumonia, particularly in high-risk groups 1 It is essential to note that influenza A is highly contagious, spreading through respiratory droplets when infected people cough, sneeze, or talk. If you experience these symptoms, especially during flu season, rest, stay hydrated, and consider over-the-counter medications like acetaminophen or ibuprofen for fever and pain. Antiviral medications such as oseltamivir (Tamiflu) may be prescribed if started within 48 hours of symptom onset, typically at 75mg twice daily for 5 days for adults. Seek medical attention if symptoms are severe or if you're in a high-risk group.

From the Research

Symptoms of Influenza A

The symptoms of influenza A are not explicitly stated in the provided studies. However, the studies discuss the treatment and prevention of influenza A, which implies that the symptoms are similar to those of the common flu, such as fever, cough, and sore throat.

Treatment and Prevention

  • The studies discuss the use of oseltamivir and zanamivir in the treatment and prevention of influenza A 2, 3, 4, 5, 6.
  • Oseltamivir and zanamivir are neuraminidase inhibitors that can help reduce the severity and duration of influenza A symptoms 3, 4.
  • The studies also discuss the potential for resistance to oseltamivir and zanamivir, which can make treatment more difficult 5, 6.

Resistance to Oseltamivir and Zanamivir

  • The studies discuss the potential for influenza A viruses to develop resistance to oseltamivir and zanamivir 5, 6.
  • Resistance can occur through mutations in the neuraminidase gene, such as the H275Y mutation 6.
  • Cross-decreased susceptibility to oseltamivir and zanamivir can also occur, making treatment more challenging 6.

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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