What are the symptoms of H1N1 flu?

Feb 14, 2025 Source: Cainiu Health

Dr. Ren Yi

Introduction

Under normal circumstances, "Jia Liu" refers to Influenza A. Influenza A virus typically presents with symptoms such as fever, cough, headache, sore throat, weakness, and fatigue. If discomfort occurs, seek medical attention at a hospital immediately. The Influenza A virus is highly contagious and mainly spreads through droplets. During the illness, close contact with others should be avoided as much as possible, and self-isolation at home is recommended.

Generally speaking, "Avian Flu" refers to Influenza A. Influenza A typically presents with related symptoms such as fever, cough, headache, sore throat, weakness, and fatigue. If discomfort occurs, seek medical attention at a hospital immediately. A detailed explanation is as follows:

1. Fever

Fever is one of the most common symptoms. After the Influenza A virus invades the human body, it activates the immune system, leading to increased heat production and reduced heat dissipation. Fever generally lasts for 3–5 days, although the exact duration varies depending on individual differences, the viral strain, and whether treatment is administered promptly.

2. Cough

Cough is a common respiratory symptom of avian flu. Initially, it may present as a dry cough with no phlegm or only a small amount of white sticky sputum. After the virus infects the respiratory tract, it stimulates the nerve endings of the respiratory mucosa, triggering a cough reflex. As the condition progresses, the cough may worsen, and the sputum may turn yellow or greenish, indicating purulent discharge.

3. Headache

Patients often experience headaches, with varying intensity and location. The inflammatory response triggered by the viral infection releases substances such as cytokines, which can affect the nervous system and cause headaches. The pain may be localized in the forehead, both temples, or feel like a pressure sensation throughout the entire head, and it can worsen during fever.

4. Sore Throat

Patients typically experience throat pain that may intensify during swallowing. The Influenza A virus attacks the mucous membranes of the throat, causing congestion, swelling, and stimulation of pain-sensitive nerve endings. Severe sore throat may affect eating and speaking, and even swallowing saliva may cause pain.

5. Weakness and Fatigue

Patients often feel a significant lack of energy and fatigue easily. The body consumes large amounts of energy while fighting the Influenza A virus, and the inflammatory response also disrupts normal physiological functions such as energy metabolism and nervous system regulation. The feeling of fatigue is difficult to fully resolve in a short period, and patients may experience symptoms such as low spirits or excessive sleepiness.

The Influenza A virus is highly contagious and primarily spreads through droplets. Patients should avoid close contact with others during illness and ideally self-isolate at home.

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