They should bring relief within minutes. If you're taking antacids and there's no relief, then something else may be going on, something that requires a physician's evaluation. Igor Cerny, a pharmacist with FDA's Center for Drug Evaluation and Research, agreed. Two weeks is the general rule of thumb. Beyond that, taking antacids can actually mask a more serious medical problem.
Serious symptoms require professional evaluation and treatment.
A Quick Look Inside Your entire digestive system is called the alimentary canal, or GI tract. Antacids do most of their work in the stomach. But the stomach does more than just hold food. It helps with digestion, too. It secretes pepsin and hydrochloric acid, which work together to break down proteins into simpler compounds.