The invention relates to a double-stranded ribonucleic acid (dsRNA) for inhibiting the expression of the Nav1.8 gene (Nav1.8 gene), comprising an antisense strand having a nucleotide sequence which is less that 25 nucleotides in length and which is substantially complementary to at least a part of the Nav1.8 gene. The invention also relates to a pharmaceutical composition comprising the dsRNA together with a pharmaceutically acceptable carrier; methods for treating diseases caused by the expression of the Nav1.8 gene using the pharmaceutical composition; and methods for inhibiting the expression of the Nav1.8 gene gene in a cell.