Inclusion Criteria: 

• Male or female subjects age 40 through 89 years, inclusive.
• Confirmed diagnosis of IPF with clinical features consistent with the current clinical practice guidelines for IPF.
• Presence of persistent cough for at least 8 weeks that is primarily due to IPF and not responsive to antitussive therapy.
• Daytime cough severity score of > 40 mm on a 100-mm VAS at the Screening Visit.
• 24-hour average cough count of at least 10 coughs per hour using an objective cough-count monitor during Screening.
• Forced Vital Capacity (FVC) > 45% predicted value within 4 weeks of the Screening Visit.
• Life expectancy of at least 12 months.
• Willing and able to follow the study required visits and assessments.
• Willing and able to use the cough monitor for 24-hour periods at select study visits.
• Willing and able to provide written informed consent prior to study-related procedures.

Exclusion Criteria: 

• Current or recent history of clinically significant medical condition, laboratory abnormality, or illness that could place the subject at risk or compromise the quality of the study data as determined by the investigator.
• Significant coronary artery disease (i.e., myocardial infarction within 6 months or unstable angina within 1 month of the Screening Visit).
• An upper or lower respiratory tract infection within 4 weeks of the Screening Visit.
• Acute exacerbation of IPF within 6 months of the Screening Visit (Collard et al., 2016).
• Lung transplantation expected within 12 months.
• Requiring supplemental O2 > 4 litres/min to maintain peripheral arterial O2 saturation (SpO2) > 88% at rest.
• History of malignancy likely to result in significant disability or likely to require significant medical or surgical intervention within the next 2 years. This does not include minor surgical procedures for localized cancer (e.g., basal cell carcinoma, squamous cell, prostate carcinoma or cervical carcinoma in situ).
• Current smoker (i.e., use of tobacco products within the last 3 months).
• Current or recent history of drug or alcohol abuse within 12 months of the Screening Visit.
• Participation in any other investigational drug study within 4 weeks of the Screening Visit or within 5 times the elimination half-life of an investigational drug.
• Use of the following drugs for cough management within 4 weeks of the Screening Visit:
  • prednisone, opiates, baclofen, gabapentin, pregabalin, thalidomide, amitriptyline, inhaled corticosteroids, or inhaled bronchodilators.
• Use of ACE inhibitors or cromolyn sodium within 4 weeks of the Screening Visit.
• Females who are pregnant or breastfeeding, or if of child-bearing potential unwilling to practice acceptable means of birth control during the study (e.g., abstinence, combination barrier and spermicide, hormonal, or male partner sterilization).
• History of hypersensitivity or intolerance to cromolyn sodium or its inactive ingredients.