Disclosed herein is the use of an extract from an Aster species for the preparation of a medicament for the treatment of opioid-induced constipation. The extract is extracted from fresh and/or dried roots and rhizomes of a Tatarian aster (Aster tartaricus) plant, in which the extraction uses water or 40-95% (v/v) ethanol as an extractant to obtain an extraction mixture. In some embodiments, the extraction mixture is then eluted with water followed by at least one eluent.
