In this study, Ssm6a was produced by recombinant expression in the periplasm of E. coli due its multiple disulfide bonds. Previously spider venom peptides were considered to be the best candidates for Nav1.7 inhibitors. However, Ssm6a was shown to have significantly higher specificity for Nav1.7 than spider venom peptides, exhibiting a more than 150-fold selectivity for Nav1.7 over other human Nav subtypes. In chemical pain tests using noxious chemical formalin, it was observed that the administration of Ssma6a was significantly more effective than morphine in reducing pain behaviors in rodent models. Ssma6a and morphine were similarly effective in reducing thermal and acid-induced pain.