A Randomized, Double-Blind, Placebo-Controlled, Parallel-Group Investigator-Initiated Clinical Trial to Evaluate the Efficacy and Safety of Fufang Xiolingdan Mixture in Patients with Influenza (Wind-Heat Invasion Syndrome)

INTERVENTION: Trial Group:Compound Xianlingdan Mixture, oral, 30ml each time, three times daily;Placebo Group:Placebo of Compound Xianlingdan Mixture, oral, 30ml each time, three times daily; CONDITION: Flu(influenza) PRIMARY OUTCOME: Symptoms of flu relief time; SECONDARY OUTCOME: TCM syndrome score;Relief time for individual flu symptoms;Proportion of subjects with fever relief;The incidence of influenza‐related complications (sinusitis, bronchitis, otitis media, and pneumonia);Incidence of complications/severe/critical illness influenza;Analgesic‐antipyretic drug usage and proportion;Virus negative conversion rate;Complete cooling time;Blood routine;Blood biochemistry;Urinalysis;12‐lead ECGs; INCLUSION CRITERIA: 1. Age >=18 and <65 years, both sexes eligible; 2. Meets TCM diagnostic criteria for Wind‐Heat Invading the Wei Level and Western medical diagnostic criteria for influenza; 3. Time from symptom onset to enrollment <=48 hours (symptom onset defined as the time of initial temperature elevation [axillary temperature >=37.3°C] or the appearance of >=1 systemic or respiratory symptom associated with influenza virus infection); 4. Positive test result for influenza virus; 5. All patients diagnosed with influenza virus infection must meet the following conditions: (1) Axillary temperature >=37.3°C and <39°C; (2) At least one influenza‐related systemic symptom (headache, fever or chills, muscle or joint pain, fatigue) or respiratory symptom (cough, sore throat, nasal congestion, etc.) present with moderate or greater severity; 6. Willing to participate in the trial and voluntarily sign the informed consent form.