An ingredient in chocolate called theobromine seems to reduce the activity of the vagus nerve, the part of the brain that triggers the strong cough. Scientists have been actively investigating the creation of a drug containing theobromine to replace cough syrups with codeine, which may have dangerous side effects.
http://www.contextotucuman.com/nota/100962/16_exquisitas_razones_para_comer_chocolate.html
