My brother 30 year old has some allergy problems since last 2-3 years. But this time he had dry cough and cold on 9th Nov, which turns to Phelgm cough now and since one week with running or stuffy nose. He throws out phelgm many times a day, its thin or bit thick with white , yellowish transparent color. He is taking ASCORIL expectorant only twice a day ,since a week. How much time will this take to cure itself?