Gastritis

The stomach lining has several layers, including a mucus layer that protects against the acid the stomach itself produces. When that protective layer is damaged or the immune system targets the lining, inflammation results. Mild gastritis causes discomfort. Severe gastritis can cause erosions or progress to ulcers.

• H. pylori infection (most common cause of chronic gastritis worldwide).
• NSAIDs (ibuprofen, naproxen, aspirin), especially regular use.
• Heavy alcohol use.
• Bile reflux (in post-cholecystectomy or post-gastric surgery).
• Autoimmune gastritis (immune system attacks parietal cells; causes B12 deficiency).
• Severe physiological stress (in people who are critically ill, in intensive care).
• Less common: viral infections, eosinophilic gastritis, granulomatous gastritis.

• Burning or gnawing pain in the upper abdomen.
• Nausea, especially in the morning or on empty stomach.
• Loss of appetite or fullness after small meals.
• Bloating and burping.
• Bad breath, which tracks with H. pylori infection more than with gastritis in general.
• Black or tarry stools, or vomiting blood. Both mean bleeding, and both are covered in the section below on when to get seen. Neither is something to watch and wait on.
• B12 deficiency in autoimmune gastritis (fatigue, tingling, mood changes).

1. Symptoms + history (NSAID use, alcohol, stress).
2. H. pylori test: a breath test or a stool antigen test.
3. Blood test for B12 and parietal cell antibodies if autoimmune suspected.
4. Endoscopy with biopsy is the gold standard but reserved for persistent cases or warning signs.

One thing catches people out here. Acid-suppressing medication and antibiotics both knock the bacteria back far enough to produce a false negative. NICE says to leave two weeks after stopping a proton pump inhibitor, and four weeks after finishing antibiotics, before a breath test or stool antigen test. So if you have been taking omeprazole for the symptoms and get tested a few days later, a negative result does not reliably rule the infection out. Tell whoever arranges the test what you have been taking.

• H. pylori positive: eradication treatment, which combines an acid-suppressing drug with two antibiotics. Course length differs between UK and international guidance, and the antibiotic choice depends on what you have taken before and on local resistance patterns, so this is prescribed and dosed for you rather than chosen off a page. It is worth asking for a re-test afterwards to confirm it worked.
• NSAID-related: stopping the NSAID is the treatment. If it is something you buy for aches and pains, that is straightforward, and paracetamol or an anti-inflammatory gel rubbed into the joint are usually reasonable alternatives. If it was prescribed, and this matters most for low-dose aspirin taken to protect the heart after a stroke or heart attack, do not stop it on your own. There are ways to protect the stomach while keeping the aspirin, and stopping it unsupervised carries its own risk.
• Alcohol-induced: cut down or stop.
• Symptomatic without H. pylori: a course of acid suppression, then stepping down to the lowest dose that controls symptoms rather than staying on it indefinitely.
• Autoimmune: B12 replacement, usually by injection. Where the stomach lining has thinned extensively, British Society of Gastroenterology guidance recommends periodic endoscopic surveillance, because the long-term risk of stomach cancer is raised.
• Diet: avoid spicy, fatty, and very acidic foods during flares. No specific 'gastritis diet' is established by high-quality trials; advice focuses on limiting irritants you personally react to.

Most gastritis-like discomfort is exactly that. Vomiting blood or black tarry stools is bleeding until proven otherwise and an emergency: 999 in the UK, 911 in the US. Food sticking or hurting on the way down, persistent vomiting, or weight going down on its own alongside upper-tummy discomfort deserve a prompt doctor's appointment rather than another course of tablets, and discomfort that keeps returning after treatment is worth a conversation in its own right.