Gastritis is inflammation of the stomach lining. It can develop suddenly and resolve within days, or it can build gradually over months or years. Most people with gastritis have no symptoms at all, but when symptoms do appear, they typically involve upper abdominal pain, nausea, or a feeling of fullness after eating very little. The condition ranges from mild irritation to serious erosion of the stomach wall that can cause bleeding.
Types of Gastritis
Gastritis falls into a few broad categories based on how quickly it develops and what it does to the stomach lining. Acute gastritis comes on suddenly, often after exposure to something irritating like alcohol, painkillers, or cocaine. It can erode the stomach lining quickly, creating shallow breaks and even ulcers that bleed. Chronic gastritis develops slowly and persists for a long time, sometimes years, before causing noticeable problems.
Within those categories, gastritis is either erosive or nonerosive. Erosive forms physically wear away the stomach lining, creating open sores. Nonerosive forms cause inflammation without visible damage to the surface. Autoimmune gastritis, for example, is chronic and typically nonerosive. H. pylori gastritis, caused by a bacterial infection, is chronic and one of the most common forms worldwide.
What Causes It
The three most common causes are H. pylori infection, regular use of common painkillers like ibuprofen or aspirin, and autoimmune reactions where the body attacks its own stomach cells.
H. pylori bacteria damage the stomach in several ways at once. They attach to the cells lining the stomach and physically damage tiny surface structures called microvilli. They also release a toxin that destroys cells from the inside and produce enzymes that break down the protective mucus layer. Once that mucus barrier is compromised, stomach acid can reach the vulnerable cells underneath. The bacteria even produce ammonia as a byproduct, which is directly toxic to stomach tissue. Over time, this damage triggers chronic inflammation and can lead to ulcers.
Painkillers in the NSAID class (ibuprofen, naproxen, aspirin) cause gastritis through a different mechanism. Your stomach lining depends on chemical messengers called prostaglandins to maintain its protective mucus layer and regulate blood flow. NSAIDs block the enzymes that produce prostaglandins. Without that protection, the stomach begins contracting more aggressively, its lining becomes more permeable, and immune cells flood the area producing damaging free radicals. The result is inflammation, erosion, and sometimes ulcers, particularly with regular or heavy use.
Autoimmune gastritis occurs when the immune system mistakes the acid-producing cells in the stomach for a threat. These cells, located in the upper and middle portions of the stomach, have two critical jobs: producing hydrochloric acid and producing a protein called intrinsic factor that your body needs to absorb vitamin B12. As the immune system destroys these cells over time, acid production drops and B12 absorption fails. This can eventually cause pernicious anemia, a condition where the body can’t make enough healthy red blood cells due to B12 deficiency.
Symptoms to Recognize
Many people with gastritis feel nothing. When symptoms do show up, they overlap heavily with general indigestion: a burning or gnawing pain in the upper abdomen, nausea, vomiting, feeling uncomfortably full early in a meal, or losing your appetite. Some people lose weight without trying.
More serious symptoms point to bleeding in the stomach. These include black or tarry stools, vomit that contains red blood or looks like coffee grounds, unexplained fatigue, lightheadedness, or shortness of breath. Mild stomach bleeding can also go completely unnoticed because the amount of blood in your stool is too small to see without a lab test.
How Gastritis Is Diagnosed
Diagnosis usually involves an upper endoscopy, where a thin, flexible camera is passed through the mouth into the stomach. The doctor looks for visible signs of inflammation, erosion, or thinning of the stomach lining. In advanced cases, the blood vessels beneath the mucosa become visible through the thinned tissue. Sticky, dense mucus and small polyps may also be present.
During the endoscopy, small tissue samples (biopsies) are typically taken. Under a microscope, pathologists look for specific changes: immune cells infiltrating the spaces between stomach glands, damage or loss of acid-producing cells, and structural changes in the gland tissue. H. pylori testing is recommended for anyone with gastritis or precancerous stomach changes, and confirming that treatment successfully eliminates the bacteria is considered standard practice.
Treatment and Acid Reduction
Treatment depends on the cause. For H. pylori, the goal is to eliminate the bacteria with a combination of antibiotics and acid-suppressing medication. For NSAID-related gastritis, stopping or reducing the offending painkiller is the most important step.
Regardless of the cause, reducing stomach acid gives the lining time to heal. Two main classes of medication do this. Proton pump inhibitors (PPIs) are the stronger option, blocking acid production at its source. H2 receptor blockers are a milder alternative available over the counter. These work by reducing the signals that tell your stomach to produce acid. They’re typically taken once or twice daily, with a single bedtime dose being effective for many people. For autoimmune gastritis, treatment focuses on managing B12 deficiency through supplementation, since the underlying immune process has no cure.
Foods That Help and Hurt
Diet won’t cure gastritis, but it can significantly affect how your stomach feels day to day. Foods that tend to soothe an inflamed stomach include leafy greens like spinach and kale, oily fish such as salmon and sardines, nuts, fresh berries, ginger, and turmeric. High-fiber foods, low-fat options, and noncarbonated drinks are generally well tolerated. Probiotic-rich foods like natural yogurt, sauerkraut, kefir, kimchi, and miso can support a healthier gut environment.
On the other side, several common foods and drinks tend to make gastritis worse:
- Alcohol and carbonated drinks
- Spicy foods
- Highly acidic foods like tomatoes and citrus fruits
- Fatty and fried foods, full-fat dairy, and red meat
- Coffee (especially on an empty stomach)
Long-Term Risks of Chronic Gastritis
Most cases of gastritis resolve with treatment and don’t cause lasting harm. Chronic gastritis that goes untreated, however, carries a small but real risk of more serious outcomes. A large observational study tracking patients for 20 years found that roughly 1 in 85 people with gastritis developed stomach cancer over that period. For comparison, the rate was 1 in 256 for people with normal stomach linings. As the stomach lining deteriorates further into atrophic gastritis (where glands are lost) or intestinal metaplasia (where stomach tissue begins resembling intestinal tissue), the risk climbs to about 1 in 50 and 1 in 39, respectively.
These numbers are still relatively low in absolute terms, particularly in Western countries. But they underscore why chronic gastritis, especially from H. pylori, is worth treating rather than ignoring. Eliminating H. pylori removes the ongoing source of inflammation, and current guidelines recommend testing and eradication for anyone found to have precancerous stomach changes.