A Study to Explore if Long-term Use of Mucinex Can Help With Symptoms in Patients With Stable Chronic Bronchitis.

Inclusion Criteria: * Adult patients with a diagnosis of SCB at recruitment, male and female, over 40 years of age * A Pulmonary Function Test with FEV1/FVC less than 0.7 (70%) at the time of enrollment or at least a 10 year history of cigarette abuse. * Patients who have chronic sputum production 3 months out of the year for 2 consecutive years and a productive cough as part of their symptoms. * Patients who understand and are able to fill out a questionnaire and ePRO weekly * Patients who have not used guaifenesin containing products within one month of the time of study enrollment * Patients with 6 to 12 (ideally 12)-month historical data - retrieved from either electronic medical records (EMR), electronic health records (EHRs), or provided by the patient via interview. Rescue medicine: • No rescue medicine will be provided. Information regarding concurrent rescue medications, either OTC or via prescription, will be collected. Exclusion Criteria: * Patients who are pregnant or breastfeeding * Participation in another study involving an investigational product within 30 days of the baseline visit * Pulmonary diagnosis other than CB, (such as cystic fibrosis, alpha-1 antitrypsin deficiency, bronchiectasis, or pulmonary fibrosis) * Active lung cancer or history of lung cancer if it has been less than 2 years since lung resection or other treatment including chemotherapy or radiation. If the patient has a history of lung cancer, they must be in remission * Psychiatric disorder that precludes participation in the study * History of alcohol and/or drug abuse within one year of study start * Patients taking intermittent antibiotics and patients taking oral and systemic corticosteroids (e.g., prednisone at a dose of \> 10 mg/day). * Patients on a chronic stable dose of macrolide antibiotics at the start of the study may be included at the discretion of the Principal Investigator. * Patients who had an acute exacerbation of chronic bronchitis within a period of one month of starting the study that required systematic steroids or antibiotics * Hypersensitivity to guaifenesin, or any other excipient listed in the product.