pH in the stomach

Definition - What is the normal pH level in the stomach?

The stomach contains what is known as gastric juice, a clear, acidic liquid. This contains dilute hydrochloric acid in large quantities.

The pH value of gastric juice is on an empty stomach, i.e. without food, between 1.0 and 1.5. If the stomach is filled with chyme, the pH value in the stomach rises to values ​​between 2 and 4. On an empty stomach or filled with food, the pH value in the stomach remains in the acidic range.

What is the pH of the stomach acid?

Stomach acid is an aqueous solution that contains hydrochloric acid. The acid is necessary to break down the chyme in the stomach so that it can be further processed in the intestine. The term gastric juice describes the complete mixture that contains all enzymes, so-called Mucin, Bicarbonate, hydrochloric acid, water etc., i.e. all substances that are produced in the stomach.

Since gastric juice consists to a large extent of gastric acid and water, the terms gastric juice and gastric acid are mostly used synonymously (synonymously). Due to the high hydrochloric acid content, the pH value of the stomach acid is in the acidic range between 1 and 1.5. If you eat and your stomach is filled with chyme, the pH value rises to values ​​between 2 and 4. The pH value of gastric acid usually always remains in the acidic range.

If the stomach glands produce too much or too little stomach acid, the pH in the stomach can change. The balance between the breakdown of food and the protection of the stomach wall cells can change. Symptoms of hyperacidity such as inflammation of the gastric mucosa (Gastritis), an ulcer or Reflux (Heartburn). If there is a lack of gastric acid, digestive disorders or frequent infections can occur.

What increases the pH?

A lack of stomach acid can have several reasons. If the gastric acid in the stomach decreases, the pH value increases, so the naturally acidic pH value becomes less acidic. Incorrect / too frequent intake of gastric acid-inhibiting medication obviously leads to a decrease in acidity in the stomach and thus to an increased pH value. Examples are the proton pump inhibitors omeprazole and pantoprazole. For optimal effect, the medication must be taken according to the dose recommended by the doctor.

Chronic inflammation of the stomach lining (gastritisType A) can also lead to a rise in pH. The formation of acid in the stomach is greatly reduced. In addition, anemia caused by a vitamin B12 deficiency can also have a negative effect on gastric acid production. One speaks of one pernicious anemia. This can also be caused by inflammation of the lining of the stomach. It is not uncommon for the disease to be based on an autoimmune disease that destroys the stomach acid-producing cells in the stomach. As this results in less stomach acid, the pH value in the stomach rises.

What lowers the pH?

The pH will be too low when there is too much acid. An acidic stomach (hyperacidity) can arise when the parietal cells in the gastric glands produce too much stomach acid. Increased gastric acid production lowers the pH value.

An unhealthy diet, caffeine, smoking and stress also lead to over-acidification of the stomach, so that the pH value decreases. The caffeine from coffee and nicotine from cigarettes stimulate the stomach wall cells to produce more acid. This decreases the pH in the stomach. In addition, it is often said "The stress makes me feel bad". It is said that stress can cramp up the stomach. In this way the production of stomach acid is stimulated. The stomach acid increases, the pH value in the stomach decreases and symptoms such as heartburn occur. It can also colonize the gastric mucosa with the bacterium Helicobacter pylori lead to increased acid formation in the stomach. Infection with this bacterium often causes inflammation of the stomach lining and increases the risk of developing an ulcer in the stomach.

What are the long-term consequences of an acidic stomach?

If the stomach is briefly overly acidic, this usually does not cause any symptoms or consequences. However, if there is an increased production of gastric acid over a long period of time, the lining of the stomach and duodenum may suffer. The damage to the stomach lining can cause symptoms such as acid regurgitation, heartburn, abdominal pain, nausea, vomiting, or loss of appetite.

An acute inflammation of the stomach lining (gastritis) or an ulcer can be behind it. If you have a stomach ulcer (Gastric ulcer) the mucous membrane is damaged in one place. Often, excessive gastric acid production is responsible for the development of an ulcer. An ulcer occurs when the cell protection of the gastric mucosa and the gastric acid are no longer in balance. If the mucous membrane is not sufficiently protected from the acid or if there is simply too much acid in the stomach, the gastric mucosa can become diseased and develop an ulcer.

Long-term consequences such as gastric mucosal inflammation and stomach ulcers can often be prevented with a healthy lifestyle (balanced diet, if possible avoiding nicotine and alcohol). For other malfunctions or Helicobacter pylori Due to inflammation of the gastric mucosa, drugs such as proton pump inhibitors can be indicated and relieve symptoms and prevent worse.

You may also be interested in this topic: Symptoms of a stomach ulcer

How can you measure the pH in the stomach?

A gastric juice test, also known as a gastric secretion analysis, examines the pH value and the composition of the gastric juice. A changed pH value can provide information about various diseases. In the gastric juice test, the pH is sober and the treating doctor uses a gastric tube. This is a soft plastic tube that the doctor inserts through the nose or mouth and into the stomach after numbing the nasopharynx with a lubricant. The doctor sucks in some gastric juice through the tube, which is then examined in the laboratory. There the pH value of the gastric juice is measured.

The pH value in the stomach can also be measured indirectly with a 24-hour pH meter. This is a long-term acid measurement in the gastric section of the esophagus. This examination method is often used in gastrointestinal medicine to examine reflux symptoms, such as heartburn, in which acidic stomach contents get back into the esophagus.

Both examination methods can prove the acidity of the gastric juice. The gastric juice examination is an examination of the gastric juice in which the pH value of the gastric juice is measured directly. A reflux of gastric juice into the esophagus can be detected with 24-hour pH-metry. The pH value of the gastric juice is measured.

What are proton pump inhibitors?

Proton pump inhibitors (PPIs), also known as proton pump inhibitors, are currently the most effective drugs for reducing stomach acid production. The proton pump inhibitors reduce the release of stomach acid from the cells of the stomach wall. The acid is formed and released by the so-called parietal cells of the gastric mucosa. An enzyme (more precisely: the H + / K + -ATPase) pumps protons (protons are electrically positively charged particles, here the hydrogen particles "H +" are meant) from the parietal cells. The protons are essential for the acidic properties of stomach acid. The more protons there are, the more acidic the stomach acid is.

Proton pump inhibitors work by interfering with this mechanism. The drugs reach the parietal cells via the bloodstream and inhibit the "proton pump". This blockage is permanent, which is why the acid-reducing effect of the medication can last up to three days.


Omeprazole is an active pharmaceutical ingredient that is used for the prevention and treatment of gastric and duodenal ulcers.
It belongs to the group of drugs called proton pump inhibitors (PPIs). Often ulcers of the stomach or duodenum are caused by colonization of the bacterium Helicobacter pylori conditionally. To eradicate the germs, omeprazole is often given together with antibiotics. Omeprazole helps reduce stomach acid.


Pantoprazole is a proton pump inhibitor that is used to reduce stomach acid.
Pantoprazole is often used for heartburn and inflammation of the esophagus, but also for stomach and duodenal ulcers. The medicine also comes from the bacteria Helicobacter pylori related ulcers, reflux disease, and Zollinger-Ellison syndrome (hormone-producing cancer of the pancreas).

What is Helicobacter pylori?

Helicobacter pylori is a rod-shaped bacterium that colonizes the human stomach and can cause gastric mucosal inflammation. The bacterium gets by with little oxygen and is very common in developing countries. Worldwide, Helicobacter pylori infection occurs in 50% of the population.

These bacteria are absorbed through the mouth and thus reach the stomach, where they colonize the mucous membrane and multiply. The bacteria have optimal living conditions in the gastric mucosa, as the mucous membrane protects the germs from the aggressive gastric acid. The germs give off ammonia and live in an ammonia cloud, which also protects them from stomach acid. Acute infection with the bacterium causes vomiting and nausea. You may also experience symptoms such as heartburn, belching and gas.

A chronic infection, on the other hand, is symptom-free in many cases. If symptoms occur, it is often heartburn, stomach pressure after eating, acid regurgitation, or gas. With a chronic Helicobacter pylori Infection can eventually lead to a (peptic) gastric ulcer. The bacteria rarely promote the development of gastric cancer and a lymph gland cancer that occurs in the stomach, the MALT lymphoma. A Helicobacter pylori infection can be treated with various drugs. Mostly a "triple therapy" with two different antibiotics and a proton pump inhibitor is carried out over a week. In severe cases, quadruple therapy with a third antibiotic is used.

Learn more about the bacterium: Helicobacter pylori

Additional information
  • Inflammation of the stomach lining
  • Symptoms of inflammation of the stomach lining
  • Burning in the stomach
  • Stomach disorders
  • pH in humans