The activated Factor XI is provided as an antitussive for cough caused by the stimulation at the tracheal bifurcation such as chronic cough. A pharmaceutical composition for prevention, treatment and/or symptom amelioration of cough, comprising a polypeptide chain as an active ingredient and a pharmaceutically acceptable carrier, wherein the polypeptide chain consists of a full length amino acid sequence constituting activated Factor XI (hereinafter also referred to as "FXIa"), the amino acid sequence with one or several amino acids therein being deleted, substituted or added, or a partial sequence of either of the above amino acid sequences, or an amino acid sequence comprising as a part any of the above amino acid sequences.
