What are the symptoms of influenza?

Dec 03, 2025 Source: Cainiu Health

Dr. Ren Yi

Introduction

Influenza usually refers to the flu, an acute respiratory infectious disease caused by the influenza virus. Common symptoms include sudden high fever, headache, fatigue, respiratory discomfort, muscle aches, and sore throat. After experiencing these symptoms, patients should promptly rest at home and avoid going to crowded places to prevent spreading the virus to others.

Influenza usually refers to the flu, an acute respiratory infectious disease caused by the influenza virus. Common symptoms typically include sudden high fever, headache and fatigue, respiratory discomfort, muscle aches, sore throat, and others. A detailed analysis is as follows:

1. Sudden high fever: Influenza has a rapid onset, often presenting with sudden high fever, with body temperature commonly rising to between 39°C and 40°C. The fever typically lasts for 3 to 5 days. Some patients may experience chills or cold sensitivity, and significant fluctuations in body temperature can easily lead to physical discomfort.

2. Headache and fatigue: Patients frequently suffer from severe headaches, particularly noticeable on both sides of the head or at the back of the skull. This is accompanied by general weakness, manifesting as lethargy and weak limbs. Even mild physical activity can result in exhaustion, significantly affecting daily work and life.

3. Respiratory discomfort: Respiratory symptoms are prominent, commonly including cough and phlegm production. Initially, the sputum is mostly white and mucous-like. Some patients may also develop nasal congestion, runny nose, and sneezing. In severe cases, symptoms such as chest tightness and shortness of breath may occur.

4. Muscle aches: Body-wide muscle and joint pain is one of the typical symptoms. Pain is particularly evident in the neck, back, and limbs. The discomfort intensifies upon pressing, and a dull ache may occur during joint movement, leading to reduced flexibility and mobility.

5. Sore and swollen throat: Congestion and swelling in the throat cause noticeable pain and swelling, which worsens when swallowing food or saliva. Some patients may feel dryness or a foreign body sensation in the throat, severely affecting normal eating and voice production.

When the above symptoms appear, patients should promptly rest at home and avoid crowded places to prevent spreading the infection. It's important to stay hydrated and maintain adequate nutrition, keep indoor areas well-ventilated, and use antiviral and symptomatic treatment medications under medical guidance to promote recovery.

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Does Lianhua Qingwen treat allergic asthma?

The core effects of Lianhua Qingwen are clearing away epidemic toxins, detoxification, promoting lung function, and relieving heat. It is primarily used to treat influenza due to heat-toxin attacking the lungs, and is not intended for the treatment of allergic asthma. Allergic asthma results from an abnormal immune response to allergens and requires targeted anti-inflammatory and anti-allergy treatments. Patients with allergic asthma should seek timely evaluation and standardized treatment at a respiratory medicine department.

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Can a cold be transmitted to people nearby?

If a cold is caused by a virus (such as influenza virus or rhinovirus) and is in the early stage of illness (1–3 days when symptoms are apparent), it can easily spread to others through respiratory droplets or direct contact. When patients cough or sneeze, they release virus-containing droplets; others may become infected by inhaling these droplets or touching contaminated objects. The risk is particularly higher in enclosed environments.

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Is a person still contagious after fever subsides due to a cold?

If a cold is caused by the influenza virus, or if symptoms such as persistent cough, sore throat, and runny nose remain after fever subsides—even if the fever has only been gone for less than 24 hours—there may still be infectivity. Influenza viruses are highly contagious and can persist for a long duration; even after the fever resolves, residual virus may remain in the body and spread via respiratory droplets. The persistence of symptoms also indicates that the virus has not been completely eliminated, meaning there remains a risk of transmission.

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Can patients with viral influenza eat rice noodles?

In general, patients with viral flu can eat rice noodles, as long as they consume them in moderation. When eating rice noodles, avoid spicy broths and excessive stimulating seasonings; opt instead for clear broth or mushroom-based soup, which are more suitable. Drink plenty of warm water daily to promote viral metabolism, and ensure adequate sleep to support body recovery. Regularly open windows indoors to ventilate and maintain fresh air, and avoid crowded places to prevent cross-infection.