Stomach Acid Drugs

Medications decreasing stomach acidity have a very wide spectrum of use. They can be divided into several groups. Nowadays we distinguish three basic types of drugs with these effects.


Antacids are commonly used preparations. They have rapid and short term effect, but they may get handy in acute bout of heartburn. Their mechanism of effect is ensured by a chemical reaction with the gastric acid (hydrochloric acid - HCl), which is neutralized. The antacids usually contain substances such as sodium bicarbonate. The reaction products are water and carbon dioxide, which is belched out. Thanks to quick relief, these preparations can be used as complementary therapy in symptomatic peptic ulcers and heartburn in reflux disease.


The simplest antacid is the mentioned sodium bicarbonate, or baking soda (NaHCO3). In this case, the neutralization reaction is NaHCO3 + HCl = NaCl + H2O + CO2.

H2 blockers

The development of so-called H2 blockers (H2 antagonists) was a great success, despite the fact that they have become somewhat obsolete. The invention of H2 blockers is based on understanding of secretion of hydrochloric acid by certain cells of the gastric mucosa. It was found that one of the stimuli for acid secretion is activation of local H2 cell receptors by a substance known as histamine. H2 antagonists block those receptors and decrease the acid production. Their effect is satisfactory. The disadvantage is that there are multiple pathways of stimulation of gastric acid production. Therefore, their effect can never be absolute. In modern medicine, the H2 blockers are in the majority of indications replaced by more effective proton pump inhibitors (see below). The active compounds of H2 blockers include substances like cimetidine, ranitidine and famotidine.

Proton pump inhibitors (PPI)

Proton pump inhibitors are also known as PPI. They are the latest generation of widely used drugs against stomach acidity. They are administered in treatment of peptic ulcers and reflux disease (with- or without esophagitis). Proton pump inhibitors block the secretion of hydrochloric acid by gastric cells, but at a different level than H2 blockers. PPI block so-called proton pump, which is an enzyme complex directly responsible for release of hydrochloric acid. No matter the stimulation of secretion, all pathways meet in the proton pump. This ensures high effectiveness of proton pump inhibitors. The preparations exist in both oral (tablets) and intravenous (water solution) form.


Most commonly used proton pump inhibitors are substances known as omeprazole, lanzoprazole, pantoprazole, esomeprazole and rabeprazole.


Jiri Stefanek, MD  Author of texts: Jiri Stefanek, MD
 Sources: basic text sources