An increasing body of evidence suggests that Nav1.7 encoded by SCN9A gene may play a key role in various pain states, including acute, inflammatory and/or neuropathic pain.The inventors now report an efficient treatment for severe cases of primary erythromelagia linked to a specific SCN9A mutation. In particular the inventors demonstrated that the inhibition of JAK2 produces a rightward shift in the voltage dependent activation of mutantNav1.7 channels, thereby normalizing the function of mutant Nav1.7 channels. On this basis, the inventors treated a patient suffering from PE with very severe refractory pain with a JAK2 inhibitor (ruxolitinib) and showed the therapy leads to considerable reduction of pain. Accordingly, the present invention relates to the use of JAK inhibitors for the treatment of painful conditions involving Nav1.7 channels.