I've been having Flu since last week. Today is day 7. The cough started off dry and then day 4 it became a little productive. Pattern of cough was both dry and productive. The phlegm was light yellow for two days and then normal. Yesterday took NAC 300 mg and then started having coughing fits needing to cough heavily to remove phlegm stuck behind throat. The phlegm after excessive coughing started having blood tinged mucus.