Antacids are over-the-counter medications that help relieve heartburn and indigestion by neutralizing stomach acid. They typically contain ingredients like magnesium hydroxide, aluminum hydroxide, or calcium carbonate. These compounds work quickly to reduce acidity in the stomach, providing relief from discomfort caused by excess acid. People often use antacids for occasional symptoms, but they are not intended for long-term treatment of conditions like gastroesophageal reflux disease (GERD). While generally safe, excessive use can lead to side effects such as constipation or diarrhea, depending on the active ingredients. Always follow the recommended dosage and consult a healthcare professional if symptoms persist.