Use of a therapeutic molecule, for the treatment of specific pain conditions, wherein the therapeutic molecule is a single chain, polypeptide fusion protein, comprising: a non-cytotoxic protease, or a fragment thereof, which protease or protease fragment can cleave a protein of the exocytic fusion apparatus of a nociceptive sensory afferent; a Targeting Moiety that can bind to a Binding Site on the nociceptive sensory afferent, which Binding Site can undergo endocytosis to be incorporated into an endosome within the nociceptive sensory afferent; a protease cleavage site at which site the fusion protein is cleavable by a protease, wherein the protease cleavage site is located between the non-cytotoxic protease or fragment thereof and the Targeting Moiety; and a translation domain that can translocate the protease or protease fragment from within an endosome, across the endosomal membrane and into the cytosol of the nociceptive sensory afferent.