Protestantism also spread in Korea. In 1960 one in twenty Koreans identified as Protestant. By 2010 that number was one in four. In 2020 Korea was home to five of the world’s largest churches, the largest of which, Yoido Full Gospel Church, began in 1961 and was believed to have 800,000 members in 2018.
Based on studies, guaifenesin is the only expectorant with any evidence of effectiveness. However, trial results are not convincing and guaifenesin is probably little or no better than placebo. Given its proven safety record, absence of drug interactions, placebo properties and the public's desire to treat productive coughs with a home remedy it would seem reasonable to supply OTC cough medicines containing guaifenesin