Stomach inflammation, medically called gastritis, happens when the protective lining of your stomach becomes irritated, damaged, or worn down. It affects roughly 1 in 200 people globally each year, with rates climbing significantly after age 50. The causes range from a common bacterial infection to everyday pain relievers sitting in your medicine cabinet.
How the Stomach Lining Normally Protects Itself
Your stomach produces powerful acid to break down food, yet it doesn’t digest itself because a thick layer of mucus shields the inner wall. Your body also produces natural compounds called prostaglandins that regulate this mucus production, control blood flow to the lining, and help damaged cells repair themselves. When something disrupts any part of this defense system, acid begins to irritate the exposed tissue, triggering inflammation.
This inflammation can be mild and temporary (acute) or persistent over months or years (chronic). In some cases, the irritant actually erodes the lining and creates small wounds called ulcers. In others, the lining is inflamed without any visible damage at all.
The Most Common Causes
H. pylori Infection
A bacterium called Helicobacter pylori is the single most common cause of chronic stomach inflammation worldwide, and its prevalence increases with age. It survives the harsh acid environment by producing an enzyme that neutralizes the acid in its immediate surroundings. This lets the bacteria burrow into the mucus layer and attach to the stomach wall, where it triggers a sustained immune response. Many people carry H. pylori for years without symptoms, but the ongoing low-grade inflammation can eventually thin the lining and raise the long-term risk of ulcers or, in rare cases, stomach cancer.
Pain Relievers and Anti-Inflammatory Drugs
Over-the-counter painkillers like ibuprofen, naproxen, and aspirin are among the most frequent culprits. These drugs work by blocking the production of prostaglandins, the same compounds your stomach relies on to maintain its protective mucus barrier. Without adequate prostaglandin activity, the lining becomes more vulnerable to acid damage. Taking these medications occasionally is unlikely to cause lasting problems, but regular or high-dose use can lead to erosive gastritis, where the lining develops visible sores that may bleed.
Alcohol
Heavy drinking irritates the stomach lining directly and can also loosen the valve that separates the stomach from the small intestine. When this valve doesn’t close properly, bile (a digestive fluid produced by the liver) washes backward into the stomach. Bile is alkaline and corrosive to stomach tissue in a different way than acid, causing a distinct form of irritation called bile reflux gastritis.
Autoimmune Gastritis
In some people, the immune system mistakenly attacks the cells in the stomach lining that produce acid and a protein called intrinsic factor. This protein is essential for absorbing vitamin B12. Over time, the immune attack destroys these specialized cells, leading to low stomach acid, poor B12 absorption, and eventually a condition called pernicious anemia. Autoimmune gastritis tends to develop slowly and is often diagnosed only after blood tests reveal unexplained B12 deficiency or anemia.
Other Triggers
Severe physical stress on the body, such as major surgery, burns, or critical illness, can trigger acute gastritis. Smoking weakens the stomach’s defenses and compounds the damage from other irritants. Chronic bile reflux can also occur after certain stomach surgeries, even without heavy alcohol use.
What Stomach Inflammation Feels Like
Many people with gastritis have no symptoms at all, which is part of what makes chronic cases tricky. When symptoms do appear, the most common is a vague, hard-to-locate pain or burning in the upper abdomen, roughly in the area between your belly button and your lower ribs. You might also notice nausea, bloating, a feeling of fullness after eating only a small amount, or loss of appetite.
If the inflammation has progressed to the point of creating ulcers, the pain often becomes sharper and more localized. Some people describe it as a gnawing sensation that paradoxically improves right after eating, then returns. More serious warning signs include vomiting material that looks like coffee grounds (which indicates digested blood) or dark, tarry stools. These suggest active bleeding and need prompt medical attention.
How Gastritis Is Diagnosed
A doctor will typically start with your symptom history and a physical exam. If an infection is suspected, a breath test or stool test can confirm H. pylori. The breath test involves drinking a small amount of a special liquid, then blowing into a sealed bag. If H. pylori is present in your stomach, the bacteria break down the liquid in a detectable way that shows up in your breath sample.
For more persistent or severe symptoms, an endoscopy gives the clearest picture. A thin, flexible tube with a camera is passed through the throat into the stomach, allowing the doctor to see the lining directly and look for redness, swelling, or erosions. During this procedure, tiny tissue samples can be taken for lab analysis. These biopsies can confirm the type of gastritis, check for H. pylori, and rule out more serious conditions.
What Helps the Stomach Heal
The most important step is removing whatever is causing the inflammation. If H. pylori is the problem, a course of antibiotics combined with acid-reducing medication clears the infection in most people. If painkillers are the cause, switching to a different type of pain relief or taking the lowest effective dose allows the lining to recover. If alcohol is the trigger, cutting back or stopping gives the stomach a chance to repair itself.
Acid-suppressing medications play a central role in treatment regardless of the cause. By reducing the amount of acid in the stomach, they create a less hostile environment that lets the damaged lining regenerate. Your stomach lining replaces its surface cells every few days, so once the irritant is gone, mild inflammation can improve within weeks. Chronic gastritis that has caused significant thinning of the lining takes longer and may require ongoing monitoring.
Autoimmune gastritis doesn’t have a cure, but the consequences are manageable. Regular B12 injections or high-dose supplements prevent anemia, and periodic endoscopies help monitor changes in the stomach lining over time.
Dietary Changes That Make a Difference
No single “gastritis diet” is backed by strong evidence, but some practical adjustments can reduce discomfort while your stomach heals. Eating smaller, more frequent meals prevents the stomach from producing large surges of acid at once. Spicy foods, acidic foods like citrus and tomatoes, and caffeinated drinks bother some people but not others, so it’s worth paying attention to your own triggers rather than following a rigid list.
Alcohol and smoking are worth eliminating entirely during recovery. Both directly impair the stomach’s ability to maintain its protective barrier, and continuing either one while trying to heal is working against yourself. Once symptoms resolve and the underlying cause has been treated, most people can return to a normal diet without restrictions.
When Inflammation Becomes a Longer-Term Concern
Most cases of gastritis resolve completely once the cause is addressed. The more serious concern is chronic, untreated inflammation that persists for years. Long-standing H. pylori infection or autoimmune gastritis can cause the stomach lining to thin permanently (atrophic gastritis) and the normal stomach cells to be replaced by a different cell type. This process, called intestinal metaplasia, is considered a risk factor for stomach cancer. The progression is slow, typically unfolding over decades, and not everyone with chronic gastritis develops these changes. But it’s one of the reasons persistent upper abdominal symptoms are worth investigating rather than simply managing with antacids indefinitely.