According to the study, cough is often distressing for patients with pneumonia, and as a result they often use over-the-counter cough medications (mucolytics or cough suppressants). These might provide relief in reducing the severity of cough, but conversely, suppression of the cough mechanism might impede airway clearance and cause harm.
The research found that over the counter cough medications are not necessarily beneficial for patients who are suffering from acute pneumonia. Mucolytics may be, but there is insufficient evidence to recommend them as an adjunctive treatment of acute pneumonia. The paper concluded that this leaves only theoretical recommendations that over the counter medications containing codeine and antihistamines should not be used in young children.