Antacids are agents that neutralize hydrochloric acid already secreted by the stomach and quickly relieve heartburn, acid reflux and discomfort in reflux and dyspepsia. Unlike H2-receptor blockers and proton-pump inhibitors (PPIs), antacids do not suppress the production of acid but only reduce its acidity for a short time.
The main active ingredients are aluminum and magnesium salts, calcium carbonate and sodium bicarbonate (baking soda). These are symptomatic remedies: they do not treat the cause and do not replace a workup for persistent complaints.
Types and side effects
Different salts behave differently: magnesium preparations loosen the stool, while aluminum and calcium salts are constipating, so they are often combined. Effervescent forms with sodium bicarbonate deliver a lot of sodium and are undesirable in hypertension; long-term aluminum use is debated in connection with bone risk.
Calcium carbonate is also a source of calcium, and magnesium antacids of magnesium; in kidney disease their excess can accumulate. Reasonable one-off relief for heartburn is safe, but a regular need for antacids is a reason to see a doctor.
Effect on nutrient absorption
By lowering acidity, antacids alter the absorption of a number of drugs and nutrients. Absorbing non-heme iron requires an acidic environment, so antacids and other acid-lowering agents impair iron absorption and can contribute to its deficiency.
Prolonged acid suppression (especially with PPIs and H2 blockers) impairs the release of vitamin B12 from food and its absorption. Antacids also bind some antibiotics (tetracyclines, fluoroquinolones), so they are taken at least 2 hours apart from other drugs.
Calculate using this marker
Calculators where Antacids is used directly:
Frequently asked questions
How do antacids differ from PPIs and H2 blockers?
Antacids neutralize acid already secreted and act quickly but briefly. PPIs and H2 blockers reduce acid production itself; they work more slowly but longer. Frequent heartburn calls for a doctor, not constant antacids.
Can antacids cause iron or B12 deficiency?
Acid-lowering agents impair the absorption of non-heme iron, and long-term use of PPIs/H2 blockers impairs the absorption of vitamin B12 from food. With prolonged use these values are worth monitoring.