Internal liquid agent

An internal liquid agent containing ambroxol hydrochloride, a pigment, polyethylene glycol, and an optional gallic acid or a derivative thereof, such that change in color of the ambroxol hydhrochloride due to irradiation of light is suppressed, precipitate is not formed, discoloration of the pigment due to heat is suppressed, and bitterness of the ambroxol hydrochloride is suppressed.