Gastritis is inflammation of the gastric mucosa of the stomach. Depending on the cause, gastritis may persist acutely or chronically and may coincide with more serious conditions such as atrophy of the stomach.
Commonly, the inflammation of gastritis results from infection with the same bacterium that causes most stomach ulcers. Gastritis may occur suddenly (acute gastritis), or it can occur slowly over time (chronic gastritis). In spite of the many conditions associated with gastritis, the signs and symptoms of the disease are very similar: a burning pain in your upper abdomen and, occasionally, bloating, belching, nausea or vomiting. In some cases, gastritis can lead to ulcers and an increased risk of stomach cancer. For most people, however, gastritis isn't serious and improves quickly with treatment. Acute gastritis occurs suddenly and is more likely to cause nausea and burning pain or discomfort in your upper abdomen. Chronic gastritis develops gradually and is more likely to cause a dull pain and a feeling of fullness or loss of appetite after a few bites of food. For many people, though, chronic gastritis causes no signs or symptoms at all. Occasionally, gastritis may cause stomach bleeding, but it's rarely severe. But be aware that bleeding in your stomach that causes you to vomit blood or pass black, tarry stools requires immediate medical care.

Symptoms & Causes
The signs and symptoms of gastritis include:

• A gnawing or burning ache or pain (indigestion) in your upper abdomen that may become either worse or better when you eat
• Nausea
• Vomiting
• Loss of appetite
• Belching or bloating
• A feeling of fullness in your upper abdomen after eating
• Weight loss

A number of factors can contribute to or trigger gastritis, including:

• Bacterial infection. People infected with Helicobacter pylori (H. pylori) can experience gastritis — most commonly chronic gastritis.
• Regular use of pain relievers. Nonsteroidal anti-inflammatory drugs (NSAIDs), such as aspirin, ibuprofen (Advil, Motrin, others) and naproxen (Aleve), can cause both acute gastritis and chronic gastritis.
• Excessive alcohol use.
• Stress. Severe stress due to major surgery, traumatic injury, burns or severe infections can cause acute gastritis.
• Bile reflux disease. Bile — a fluid that helps you digest fats — is produced in your liver and stored in your gallbladder. When it's released from the gallbladder, bile travels to your small intestine through a series of thin tubes. Normally, a ring-like sphincter muscle (pyloric valve) prevents bile from flowing into your stomach from your small intestine. But if this valve doesn't work properly, or if it has been removed because of surgery, bile can flow into your stomach, leading to inflammation and chronic gastritis.
• Your own body attacking cells in your stomach. Called autoimmune gastritis, this rare condition occurs when your body attacks the cells that make up your stomach lining. This produces a reaction by your immune system that can wear away at your stomach's protective barrier.
• Other diseases and conditions. Gastritis may be associated with other medical conditions, including HIV/AIDS, Crohn's disease, parasitic infections, some connective tissue disorders, and liver or kidney failure.

Treatment
Treatment of gastritis depends on the specific cause. Acute gastritis caused by NSAIDs or alcohol may be relieved by stopping use of those substances. Chronic gastritis caused by H. pylori infection is treated by eradicating the bacteria. Most gastritis treatment plans also incorporate medications that treat stomach acid in order to reduce signs and symptoms you're experiencing and promote healing in your stomach.