A Selective Seratonin Reuptake Inhibitor (SSRI) is an antidepressant medication that typically decreases anxiety as well as depression (Prozac, Zoloft, Paxil). It acts by blocking the reuptake of serotonin. It is contraindicated in patients with carcinoid syndrome. It may preciptate a carcinoid crisis or worsen symptoms of carcinoid syndrome.