Alka-Seltzer is an over-the-counter medication that is used for the temporary relief of various symptoms caused by too much stomach acid, such as heartburn, upset stomach, or indigestion. It is an effervescent antacid and pain reliever that contains three active ingredients: aspirin, sodium bicarbonate, and anhydrous citric acid. The aspirin is a pain reliever and anti-inflammatory, the sodium bicarbonate is an antacid, and the citric acid reacts with the sodium bicarbonate and water to form effervescence. Alka-Seltzer is also marketed for relief of minor aches, pains, inflammation, fever, headache, stomachache, indigestion, acid reflux, and hangovers, while neutralizing excess stomach acid. It is available in many different flavors and sold in foil packets, each containing two tablets. Alka-Seltzer is not considered an antiemetic (nausea medication), but it can help relieve nausea from heartburn or an upset stomach after eating or drinking too much.