What are the symptoms of H1N1 flu?

Feb 14, 2025 Source: Cainiu Health

Dr. Ren Yi

Introduction

In general, "A flu" refers to influenza A, whose symptoms include high fever, cough with phlegm, muscle and joint pain, headache, fatigue, and weakness. However, please note that the severity of influenza A symptoms varies, depending on the patient's age, immune status, and whether timely treatment is received. If symptoms are severe or persist, prompt medical attention should be sought, and treatment should follow the doctor's recommendations.

Generally speaking, "Avian Flu" refers to Influenza A. Symptoms of Influenza A include high fever, cough with phlegm, muscle and joint pain, headache, fatigue, and weakness. A detailed analysis is as follows:

1. High Fever

After the Influenza A virus invades the human body, it activates the immune system to fight the virus. The release of cytokines affects the body's temperature regulation center, rapidly increasing the patient's body temperature to above 39°C, accompanied by chills and shivering.

2. Cough with Phlegm

The Influenza A virus primarily attacks the respiratory mucosa, causing inflammatory reactions such as mucosal congestion, swelling, and increased secretions, thereby triggering symptoms like coughing and phlegm production. In severe cases, the cough may become intense, affecting sleep and rest.

3. Muscle and Joint Pain

Infection with the Influenza A virus causes systemic inflammatory reactions in muscles and joints, leading to lactic acid production, which stimulates nerve endings and causes pain. It may also trigger congestion and edema of the joint synovium, compressing surrounding nerves and causing pain.

4. Headache

Inflammatory reactions caused by Influenza A virus infection, fever, blood vessel dilation, and nerve stimulation collectively contribute to headaches. Inflammatory mediators stimulate surrounding nerves, leading to abnormal nerve conduction and headaches.

5. Fatigue and Weakness

After Influenza A virus infection, the body consumes significant energy to combat the virus, reducing energy reserves. Additionally, symptoms such as fever and muscle pain cause discomfort and difficulty in movement, further exacerbating the feeling of fatigue.

However, it should be noted that the severity of Influenza A symptoms varies, depending on the patient's age, immune status, and whether timely treatment is received. If symptoms are severe or persist without improvement, prompt medical attention should be sought, and treatment should follow the doctor's recommendations.

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