A Multicenter, Randomized, Double-blinded, Placebo-controlled, Parallel, Phase II Clinical Trial to Evaluate the Efficacy and Safety of HL301 versus Placebo in acute bronchitis patients.

Endpoint: BSS, The improvement and improvement rate of the tester for the treatment response, The satisfaction of the subject, Total usage of Acetaminophen

Inclusion Criteria:

1. Both gender, 19 years ≤ age ≤ 80 years
2. (Bronchitis Severity Score)* ≥ 5point at Visit 2 (Randomized Visit)
3. Acute bronchitis within 48hr based on Visit 2 (Randomized Visit)
4. Those who can comply with the requirements of clinical trials
5. Written consent voluntarily to participate in this clinical trial

Exclusion Criteria:

1. Patients with respiratory and systemic infections requiring systemic antibiotic therapy
2. Patients with bleeding tendency
3. Patients who investigators determines to severe respiratory disease that would interfere with study assessment
4. Patients who were treated with oral systemic adrenocortical hormone or immunosuppressive drug within 4 weeks prior to Visit 2
5. Patients who were treated with oral antihistamines, ACE suppressive. or systemic/inhalative glucocorticosteroid within 2 weeks prior to Visit 2