Most people infected with H. pylori have no symptoms at all. The bacterium can live in the stomach lining for years or even decades without causing noticeable problems. When symptoms do appear, they typically involve a dull, gnawing pain in the upper abdomen, bloating, frequent burping, nausea, and a loss of appetite. A screening study of over 1,000 asymptomatic adults found that nearly 64% tested positive for H. pylori, highlighting just how common silent infections are.
How the Infection Causes Symptoms
H. pylori survives in the harsh environment of the stomach by producing an enzyme that neutralizes stomach acid in its immediate surroundings. This weakens the protective mucous lining of the stomach, allowing acid to irritate the tissue underneath. The bacteria also attach directly to stomach cells, triggering chronic inflammation called gastritis. Over time, that inflammation is what produces the discomfort most people associate with an H. pylori infection.
The Most Common Symptoms
When H. pylori does cause symptoms, the hallmark is a burning or gnawing pain in the middle of the abdomen, roughly between the navel and the breastbone. This pain often shows up two to three hours after eating, or in the middle of the night when the stomach is empty. Eating food or taking an antacid typically eases it, at least temporarily. The pain tends to come and go over days or weeks rather than staying constant.
Beyond stomach pain, common symptoms include:
- Bloating and excess gas
- Frequent burping
- Nausea or an upset stomach
- Loss of appetite
- Unintentional weight loss
These symptoms overlap heavily with other digestive conditions, which is one reason H. pylori often goes undiagnosed without testing.
Effects on Appetite and Weight
H. pylori doesn’t just make your stomach hurt. It can also change how hungry you feel. The infection reduces your stomach’s production of ghrelin, the hormone that signals hunger to your brain. Research in elderly patients found that H. pylori infection was linked to significantly lower ghrelin levels, lower daily calorie intake, and lower body mass index. The more severe the stomach inflammation and tissue damage, the greater the drop in hunger hormones. For some people, especially older adults, this can contribute to gradual, unexplained weight loss and poor nutrition over time.
Symptoms in Children
Children with H. pylori experience many of the same symptoms as adults, but the pattern can look different. Belly pain is the most common complaint, and it often strikes between meals or in the early morning hours when the stomach is empty. Eating usually helps. Children may also have recurring nausea, vomiting, bloating, and burping. In some cases, persistent infection leads to a noticeable loss of appetite and weight loss over weeks or months.
Because kids can’t always describe their symptoms precisely, recurrent belly pain that wakes them at night or consistently worsens on an empty stomach is a pattern worth paying attention to.
What Happens If It Goes Untreated
Left untreated, chronic H. pylori infection can progress beyond general discomfort. The ongoing inflammation gradually thins the stomach lining, a condition called atrophic gastritis, and can lead to peptic ulcers in the stomach or upper small intestine. Ulcers are the source of more intense symptoms: sharp or severe abdominal pain, a burning sensation that doesn’t respond to antacids, and in some cases, internal bleeding.
Over the long term, chronic H. pylori infection also raises the risk of stomach cancer. The majority of cases of gastric adenocarcinoma, the most common type of stomach cancer, are attributed to H. pylori. A rarer form of stomach cancer called MALT lymphoma is also strongly linked to the infection, with nearly all patients showing signs of H. pylori. These cancers develop over many years, not weeks, so the infection itself is treatable well before it reaches that stage.
Warning Signs That Need Immediate Attention
Certain symptoms suggest a complication like a bleeding ulcer and require urgent medical care:
- Black, tarry, or bloody stools, which indicate bleeding in the upper digestive tract
- Vomiting blood or material that looks like coffee grounds
- Sharp, sudden stomach pain that doesn’t improve
- Difficulty swallowing
- Unusual fatigue, dizziness, or fainting
Dark or tarry stool is especially important to watch for because it can signal slow, ongoing blood loss that you might not notice otherwise.
How H. Pylori Is Diagnosed
If your symptoms fit the pattern, testing is straightforward and noninvasive. The two most common options are a urea breath test and a stool antigen test. In the breath test, you swallow a small amount of a harmless substance, and the test detects whether H. pylori bacteria break it down in your stomach. It’s highly accurate, with a sensitivity around 92 to 94%. The stool antigen test checks for traces of the bacteria in a stool sample and has a sensitivity of roughly 83%. Both are reliable enough to guide treatment decisions without needing an endoscopy in most cases.
If you’re experiencing recurring upper abdominal pain that worsens on an empty stomach, persistent bloating, or unexplained nausea, testing for H. pylori is a reasonable step. Treatment, when needed, involves a course of antibiotics combined with acid-reducing medication, and most infections clear within a few weeks.