12 Possible Gastritis Causes

2. Overuse of NSAIDs

Nonsteroidal anti-inflammatory drugs, or NSAIDs, irritate your stomach lining when you use them too often. These drugs reduce pain and swelling, but they also lower the amount of protective mucus in your stomach. Without this layer, stomach acid damages the tissue and leads to inflammation.

You may take NSAIDs for headaches, joint pain, back pain, or arthritis. Problems often start when you use high doses or take them for many weeks or months. Taking more than one NSAID at the same time raises your risk even more. Your risk increases if you are older, drink alcohol often, or have had stomach ulcers before. Using NSAIDs along with certain blood thinners or steroid medicines makes stomach injury more likely.

Even over-the-counter doses can cause harm if you use them daily without medical advice. Common warning signs include upper belly pain, nausea, and a feeling of fullness. In more serious cases, you might notice black stools or vomit that looks like coffee grounds, which signals bleeding in your stomach.

3. Excessive Alcohol Consumption

Drinking large amounts of alcohol irritates the lining of your stomach. Alcohol increases stomach acid and weakens the protective layer that shields your stomach from damage. Over time, this leads to inflammation, known as gastritis. You face a higher risk if you binge drink or drink heavily on a regular basis.

Even short periods of heavy drinking can trigger sudden gastritis. Long-term alcohol use leads to chronic irritation that lasts for months or years. When your stomach lining becomes inflamed, you may notice symptoms such as upper belly pain, nausea, vomiting, or loss of appetite.

In more serious cases, irritation can cause bleeding. This may lead to black stools or vomit that looks like coffee grounds. Alcohol also slows healing if your stomach lining is already damaged by other causes, such as infection or certain pain relievers. The more often you drink heavily, the greater the strain on your stomach.

4. Chronic Stress

Chronic stress affects more than your mood and can irritate your stomach lining, which raises your risk of gastritis. When you feel stressed for long periods, your body releases stress hormones that can increase stomach acid and reduce blood flow to the stomach lining. Over time, this weakens the protective layer that shields your stomach from acid.

You may notice symptoms such as burning pain in your upper belly, nausea, or loss of appetite. Stress also changes how fast your stomach empties, which causes bloating or discomfort after meals. Severe physical stress has a stronger effect, and events such as major surgery, serious injury, burns, or critical illness can lead to sudden inflammation of the stomach lining.

This is sometimes called stress-related gastritis. It can develop quickly and may cause bleeding in some cases. Chronic emotional stress works more slowly. Ongoing work pressure, lack of sleep, anxiety, or long-term illness can keep your body in a constant state of tension and may make existing stomach irritation worse.

5. Radiation Exposure

Radiation exposure irritates and damages the lining of your stomach, which can lead to gastritis, especially after a high dose over a short time. Radiation used in cancer treatment near your abdomen can also affect nearby healthy tissue. High-energy radiation, such as X-rays, gamma rays, or certain cancer therapies, injures cells in your stomach lining. When these cells break down, your stomach becomes red, swollen, and painful.

You may notice symptoms such as nausea, vomiting, indigestion, or burning pain in your upper abdomen. A large dose delivered quickly is more harmful than the same dose spread out over time. Exposure to one small area is usually less severe than exposure to a large part of your body. In some cases, stomach injury appears weeks or even months after radiation therapy.

6. Injuries and Impact

Physical injuries inflame your stomach lining. When your body goes through major trauma, it shifts blood flow to protect vital organs like your heart and brain. This shift lowers blood flow to your stomach and irritates its lining. You may face this risk after severe burns, major surgery, serious car accidents, head injuries, or kidney failure.

This is often called stress-related gastritis, and it can develop quickly, especially when you are in intensive care or need a breathing machine. The stress on your body, not just your emotions, plays a key role. Direct impact to your upper abdomen can also harm your stomach.

A strong blow during sports or a fall can bruise tissues inside your body and may trigger swelling and pain in the upper belly. Severe illness can have a similar effect because the body may release chemicals that increase stomach acid while the stomach’s protective layer becomes weaker.

7. Cocaine Use

Cocaine is an illegal stimulant drug that affects your central nervous system. When you use it, your body releases high amounts of certain brain chemicals, which can raise your heart rate and blood pressure within minutes. Cocaine irritates your stomach lining and reduces blood flow to your digestive tract, making the lining more likely to swell and break down. This irritation leads to gastritis, which means inflammation of the stomach lining.

Cocaine use also increases stomach acid, adding more stress to an already irritated lining. Over time, repeated use raises the risk of stomach bleeding. If you already take medicines that irritate the stomach, such as nonsteroidal anti-inflammatory drugs, the combined effect makes damage worse.

Heavy alcohol use along with cocaine further increases irritation. Stomach pain, vomiting blood, black stools, or sudden severe abdominal pain after cocaine use may signal a serious problem that needs urgent medical attention.

8. Bile Reflux

Bile reflux happens when bile flows backward from your small intestine into your stomach. Bile is a digestive fluid that your liver makes to help break down fats. It normally moves in one direction, but problems in the digestive tract can let it rise into your stomach.

When bile irritates your stomach lining, it causes inflammation and may lead to gastritis over time. Bile reflux is less common than acid reflux, but it can still cause ongoing stomach damage if it continues. You may notice symptoms such as upper belly pain, nausea, vomiting, or a burning feeling in your stomach. Some people also feel full or bloated after eating small meals.

In some cases, bile may mix with stomach acid, which can worsen the irritation. Certain factors increase your risk, including stomach surgery, gallbladder removal, or problems with the valve that controls the flow between your stomach and small intestine. Long-term irritation from bile weakens the stomach’s protective lining.

9. Autoimmune Conditions

Autoimmune conditions cause gastritis when your immune system attacks the lining of your stomach. Your immune system normally protects you from germs. When it makes a mistake, it damages healthy tissue instead. In autoimmune gastritis, your body targets cells that produce stomach acid and a substance needed to absorb vitamin B12.

Over time, this damage thins the stomach lining and lowers acid levels in your stomach. Low vitamin B12 levels may lead to problems such as fatigue, weakness, or pale skin. Some people develop a type of anemia because their body cannot absorb this vitamin well. You may not notice stomach pain at first, since symptoms can be mild or slow to appear.

Other signs may include numbness or tingling in the hands and feet, balance problems, or memory changes when vitamin B12 stays low for a long time. Autoimmune gastritis is also more common in people with other autoimmune conditions, such as autoimmune thyroid disease or type 1 diabetes.

10. Crohn’s Disease

Crohn’s disease is a long-lasting condition that causes swelling in your digestive tract. It most often affects your small intestine and the start of your large intestine, but it can involve any part from your mouth to your anus.

Crohn’s disease mainly targets your intestines, but ongoing inflammation in your digestive system can affect nearby areas, including your stomach. When this happens, you may develop gastritis, which means the lining of your stomach becomes irritated and swollen.

If you have Crohn’s disease, your immune system reacts in an abnormal way and attacks healthy tissue in your gut, which leads to inflammation. Over time, this inflammation can spread and irritate your stomach lining. Crohn’s disease can also affect how well your body absorbs nutrients, and poor nutrition may weaken your stomach lining and make irritation worse.

11. Irritable Bowel Syndrome

Irritable bowel syndrome (IBS ) affects how your digestive system works and can lead to ongoing discomfort without causing visible damage to your stomach or intestines. Its symptoms often feel similar to gastritis, which makes it difficult to distinguish between the two conditions without medical advice.

IBS mainly affects your intestines and not your stomach lining. Common symptoms include stomach cramps, bloating, diarrhea, constipation, or both, and mucus in your stool. Stress, certain foods, or hormonal changes can make them worse. The exact cause of IBS remains unclear, but changes in how your gut and brain communicate and increased intestinal sensitivity may play a role.

IBS does not increase your risk of stomach cancer or cause bleeding in the stomach. If you notice black stools, vomiting blood, or ongoing severe pain, another condition such as gastritis may be present.

12. Unhealthy Diet

Your daily food choices can irritate the lining of your stomach. Frequent consumption of hard-to-digest or spicy foods may cause swelling and pain. Over time, unhealthy eating habits can increase your risk of gastritis.

Spicy meals, fried foods, and high-fat snacks increase stomach acid. Excess acid wears down the protective lining inside your stomach and may lead to gastritis. Eating large meals late at night also stresses your stomach. Your body needs time to break down food, and overloading it keeps acid active longer than usual.

Heavy alcohol use also damages the stomach lining. Alcohol weakens the stomach’s natural defenses, which makes it easier for acid to irritate the tissue. A diet low in fiber and high in processed foods affects how well your digestive system works. Processed foods often contain large amounts of salt, unhealthy fats, and additives, which can upset your stomach and trigger discomfort.