Influenza is an acute respiratory infectious disease caused by the influenza virus, with symptoms that typically onset suddenly and progress rapidly. Patients may exhibit noticeable symptoms within 1 to 4 days after exposure to the virus, with severity varying from person to person. Understanding the characteristics of symptoms aids in early diagnosis and treatment, reducing the risk of complications.
The manifestation of symptoms varies by age, immune system strength, and differences in viral strains. Children may primarily present with fever and muscle pain, while the elderly or those with chronic illnesses may experience more severe respiratory issues. Early recognition of symptom changes and monitoring the severity of symptoms are crucial for determining the need for medical attention.
The early symptoms of influenza typically include systemic discomfort and localized respiratory symptoms. Patients often experience a sudden feeling of fatigue, which may present as a "prodromal sign" 12 to 24 hours before fever onset. Additionally, symptoms such as a dry throat, mild nasal congestion, or sneezing are clear signs that the virus has begun to infect the respiratory mucosa.
It is noteworthy that some patients may initially misjudge their condition as a common cold, but influenza symptoms typically worsen rapidly within 24 hours, which is a clear contrast to the gradual development of a common cold.
Typical symptoms peak around the 2nd to 3rd day after onset, primarily categorized into systemic and localized respiratory symptoms. Systemic symptoms such as high fever (often exceeding 38.5°C) can last for several days and are accompanied by severe muscle aches, particularly noticeable in the lower limbs and back muscles. Respiratory symptoms include dry cough, chest tightness, and difficulty breathing, which can severely impact daily activities.
Some patients may experience gastrointestinal symptoms, such as loss of appetite, diarrhea, or nausea, which are more common in pediatric patients. This combination of systemic and localized symptoms contrasts sharply with the localized upper respiratory symptoms of a common cold.
Symptoms typically peak within 3 to 7 days after onset and then gradually alleviate. However, if symptoms do not improve after day 5 or if a secondary fever occurs, it may indicate a bacterial infection or viral pneumonia. Coughing may persist for more than two weeks, related to viral remnants or the repair process of the respiratory tract.
On days 3 to 4 after onset, patients may exhibit critical symptoms such as persistent high fever, altered consciousness, or rapid breathing. At this time, close monitoring of blood oxygen saturation and urine output is necessary to assess dehydration and organ load status. Some patients may present with metabolic symptoms such as nausea and vomiting due to metabolic disturbances.
The process of symptom relief is usually accompanied by a decrease in body temperature and coughing frequency, but some patients may experience recurrent low-grade fever during recovery, which may relate to the immune system's process of clearing the virus.
Medical attention should be sought immediately if any of the following conditions are met: high fever exceeding 39°C lasting more than 48 hours, altered consciousness or disorientation, or difficulty breathing leading to cyanosis of the lips. These symptoms may indicate severe complications such as pneumonia, encephalitis, or metabolic acidosis.
For individuals over 65 years old, pregnant women, and patients with chronic illnesses, any worsening of mild symptoms, such as abnormal blood sugar elevation in well-controlled diabetes patients or exacerbated chest pain in heart disease patients, should be treated as an emergency. In children, symptoms such as seizures, inability to eat, or skin mottling (marbled skin) may indicate severe dehydration or metabolic crisis.
Even if symptoms appear mild, if there has been contact with confirmed cases and flu-like symptoms develop, proactive rapid testing or PCR testing should be conducted to interrupt the transmission chain. Antiviral medications provided by healthcare institutions, if used within 48 hours of symptom onset, can significantly shorten the duration of illness and reduce the risk of complications.
Influenza symptoms typically onset more suddenly and severely, including high fever (above 39°C), widespread muscle aches, and extreme fatigue, while common cold symptoms are mainly nasal congestion, runny nose, and mild throat discomfort. If accompanied by severe headache or persistent cough, it is advisable to seek medical attention promptly to confirm whether it is influenza.
Why might one still contract the virus after receiving the influenza vaccine?The effectiveness of the vaccine is related to the match between the vaccine strains and the circulating virus strains, as well as individual immune responses. The strains covered by the vaccine each year are predicted based on the previous year's trends, and if the circulating strains mutate, the protective effect may be reduced. Even if infected, vaccination can still lessen the severity of symptoms and lower the risk of complications.
Why is it not advisable to excessively use antipyretics during fever?Excessive use of antipyretics may increase the burden on the liver and kidneys and may mask the true progression of the illness. It is recommended to follow medical advice on dosage control and prioritize physical cooling methods (such as tepid sponge baths). Fever is a natural response of the body to fight the virus and should not be forcibly suppressed in the short term.
Is it normal to have a persistent cough during the recovery phase of influenza? How should one respond?A dry cough or productive cough during the recovery phase is common, as the virus may damage the respiratory mucosa, requiring 1 to 2 weeks for recovery. It is advisable to consume warm fluids (such as pear soup or honey water) to soothe the throat and avoid irritants such as smoke. If coughing up blood or high fever recurs, immediate medical attention is necessary.
Can traditional Chinese medicine and Western medicine be taken simultaneously during influenza treatment?It is advisable to consult a physician before combining treatments, as some components of traditional Chinese medicine may interact with antiviral medications (such as oseltamivir), affecting efficacy or enhancing side effects. Self-combining medications may increase the burden on the liver and should be adjusted based on professional medical advice.
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