The investigators propose to conduct a pilot trial to assess the safety, tolerability and efficacy of carbidopa for the treatment of nausea in patients with FD. The pilot trial will recruit 25 patients with FD who complain of severe nausea that affects their quality of life. The trial will be divided into two consecutive, but independent parts. Part 1, will address the safety and tolerability of carbidopa in patients with FD using an open-label dose titration phase followed by 4-weeks of open-label treatment. Part 2, will address the efficacy of carbidopa for the treatment of nausea in patients with FD using a randomized, placebo controlled, double blind, 4-week cross over design.