This is an open-label, multicenter, single-group study designed to determine the effectiveness of Mucinex® when used by patients to treat SCB over a 12-week period, following a 2-week run-in period of no treatment (to establish a baseline).

Data will be collected via the Vitaccess Real[TM] platform from adult patients with SCB and HCPs based in the US. During the 12-week period of receiving treatment, patient participants will take Mucinex® 12h, 2 x 600 mg (1200 mg total) twice daily and complete weekly bespoke surveys and the CASA-Q instrument. Patient-reported data will include prior usage of Mucinex®, treatment compliance, treatment satisfaction, and symptoms.

During this same period of time, HCPs will report treatment satisfaction via electronic case report forms (eCRFs), and will also have the ability to spontaneously report any treatment-emergent adverse events.

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.

There is not a plan to make IPD available.