How to cure a long coughing? an old folk said, "bird nest + pao sam + ice sugar" can cure it... yet to verify the effectiveness of this traditional chinese herbal. But no harm to try also, if it really can help.

Quoted from http://chinesefood.about.com/library/bltrivia33.htm

"Authentic bird's nest soup is made using the nests of the swiftlet, a tiny bird found throughout southeast Asia. The swiftlet lives in dark caves, using a method of echolocation similar to the bat to get around. Instead of twigs and straw, the swiftlet makes its nest from strands of its own gummy saliva, which hardens when exposed to air. Humans who harvest the swiftlet nests often come from families that have made their living this way for generations. Prying the nests from the cave walls is extremely dangerous, and many harvesters die each year."