Abstract: The invention provides short interfering nucleic acids, either single-stranded or double-stranded, that cause RNAi-induced degradation of mRNA from the Nav1.8 sodium channel gene; to pharmaceutical compositions comprising such short interfering nucleic acids; recombinant vectors comprising such short interfering nucleic acids; a method for inhibiting translation of an mRNA; a method for inhibiting expression of a polypeptide; a method for blocking the membrane potential in a cell; a method for blocking the sodium current in a cell; and a method for inhibiting chronic pain.