Achlorhydria is a condition where your stomach produces virtually no hydrochloric acid. Normal stomach acid sits at a pH of one to two, which is highly acidic. When gastric pH rises above five, the condition crosses from low stomach acid (hypochlorhydria) into achlorhydria, meaning acid production has essentially stopped. This matters because stomach acid plays a central role in breaking down food, absorbing nutrients, and killing harmful bacteria before they reach your intestines.
What Causes Achlorhydria
The most common cause is autoimmune gastritis, a condition where your immune system attacks the cells in your stomach lining that produce acid. Over time, this destroys enough of these cells that acid output drops to near zero. Autoimmune gastritis is also the primary cause of pernicious anemia, a vitamin B12 deficiency that develops because B12 absorption depends on a protein made by the same stomach cells.
Chronic infection with H. pylori, the bacterium responsible for most stomach ulcers, can also lead to achlorhydria. The infection causes long-term inflammation that gradually damages the stomach lining, sometimes progressing to severe atrophic gastritis where acid-producing cells are replaced by scar tissue. Long-term use of proton pump inhibitors (PPIs), the class of heartburn medications that suppress acid production, can push gastric pH high enough to cause functional achlorhydria in some people, though this typically reverses after stopping the medication.
Symptoms and How It Feels
Achlorhydria often develops gradually, and early symptoms can be vague enough to dismiss. Bloating, a feeling of fullness after eating only small amounts, and upper abdominal discomfort are common. Some people notice undigested food in their stool. Because stomach acid triggers the release of digestive enzymes further down the digestive tract, its absence can create a cascade of poor digestion throughout the gut.
The more significant symptoms tend to come from nutrient deficiencies that build up over months or years. Without adequate stomach acid, your body struggles to absorb calcium, iron, folic acid, vitamin B6, and vitamin B12. This can show up as fatigue, weakness, tingling or numbness in your hands and feet (from B12 deficiency), brittle nails, or bone thinning. Iron-deficiency anemia is particularly common and may be the first clue that leads to a diagnosis.
How Achlorhydria Is Diagnosed
The most direct way to diagnose achlorhydria is by measuring the pH inside your stomach. One method uses a small capsule called the Heidelberg capsule, which contains a pH sensor and a tiny radio transmitter. You swallow the capsule, and it sends real-time pH readings to an external receiver as it moves through your stomach. This gives a continuous picture of how acidic your stomach actually is.
Blood tests also provide important clues. Serum gastrin levels rise dramatically when the stomach stops making acid, because the body keeps trying to signal for more production. Gastrin levels above 500 to 1,000 pg/mL strongly suggest achlorhydria. Doctors may also check for antibodies against stomach lining cells (parietal cell antibodies) to identify autoimmune gastritis as the underlying cause, along with B12, iron, and other nutrient levels to assess the downstream effects.
Long-Term Risks
Bacterial Overgrowth
Stomach acid serves as a barrier, killing most bacteria that enter with food before they can reach the small intestine. When that barrier disappears, bacteria can colonize parts of the gut where they don’t belong, a condition called small intestinal bacterial overgrowth (SIBO). SIBO causes its own set of problems: gas, bloating, diarrhea, and worsened nutrient malabsorption. The risk of SIBO increases with age, partly because stomach acid production naturally declines in older adults.
Increased Gastric Cancer Risk
Achlorhydria represents the most severe form of atrophic gastritis, and it carries a meaningful increase in stomach cancer risk. A long-term follow-up study tracking 114 patients with achlorhydria over an average of 8.4 years found a four- to sixfold increased risk of gastric cancer compared to the general population. The cancers developed anywhere from 1 to 17 years after diagnosis, with three of the five cases appearing more than nine years later. Notably, the risk was the same whether or not the patient also had pernicious anemia. This timeline underscores why ongoing monitoring matters for people with confirmed achlorhydria.
Treatment and Management
Treatment depends on the underlying cause. If achlorhydria is driven by long-term PPI use, tapering off the medication under medical guidance can allow acid production to recover. If H. pylori infection is present, eradicating the bacteria with antibiotic therapy may help, though damage to the stomach lining isn’t always reversible. Autoimmune gastritis has no cure, so management focuses on addressing the consequences of lost acid production.
Supplementing the nutrients that depend on stomach acid for absorption is a cornerstone of management. B12 injections bypass the gut entirely, making them effective even when absorption is severely impaired. Iron and calcium supplements may also be necessary, and periodic blood work helps track whether levels stay in a healthy range.
For improving digestion itself, some practitioners recommend betaine HCl supplements taken with protein-containing meals. These capsules deliver hydrochloric acid directly to the stomach, temporarily lowering pH to aid digestion. The typical approach starts with a single capsule containing 350 to 750 mg of betaine HCl at a meal, then gradually increases the dose over several days. If you feel a burning or tingling sensation at any point, that signals the dose is too high and should be reduced. Some formulations include pepsin, a digestive enzyme that works alongside stomach acid, which may improve the overall benefit. Smaller meals generally require a lower dose. This approach is more established in integrative medicine than in conventional gastroenterology, and the formal evidence base remains limited, but the underlying logic is straightforward: replacing what the stomach no longer produces on its own.