This is a nonblinded Case-only study that evaluates the effects of Agmatine Sulfate on small fiber peripheral neuropathy. Patients will be started on Agmatine sulfate (a metabolite of Arginine) and monitored for two months. Improvement will be noted on their response to the Neuropathic Pain Questionnaire. Additionally the investigators will note improvement by performing autonomic function testing at the beginning and end of the study.