Acute functional dyspepsia, also known as heartburn, is a condition of the upper esophageal tract becomes irritated and inflamed, causing considerable discomfort. Among other things, the condition can be caused by eating too many spicy or acidic foods. Symptoms include: burning sensation in the throat or chest, nausea or a foul taste in the mouth.
In 2374, several of the crewmembers of the USS Voyager developed acute functional dyspepsia after eating Neelix's version of Rodeo Red's Red-Hot, Rootin'-Tootin' Chili in the mess hall. Lieutenant Tom Paris diagnosed it after several crewmembers complained of chest pain, and he replicated antacid to relieve their pain. (VOY: "Message in a Bottle")