In today's Washington Post Health section:

"While persistent coughing is not necessarily harmful it can have a
major impact on quality of life, and this discovery could be a huge
step forward in treating this problem."

Peter Barnes of Imperial College of London, discussing results of a
small study showing that theobromine, a chemical found in chocolate,
to be nearly a third more effective than codeine at controlling
coughs. The researchers said theobromine worked by suppressing
activity of the vagus nerve, which is responsible for causing
coughing. Unlike other cough treatments, the chemical did not cause
drowsiness.