Ulcers and the Bacteria That Causes Them
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Ulcers and the Bacteria That Causes Them

Ulcers were believed to be caused by stress, anxiety, smoking, and/or a diet rich in spicy foods. However, research has demonstrated that most ulcers are caused by a spiral-shaped bacterium known as Helicobacter pylori (H. pylori). The other common cause of ulcers are NSAIDs (nonsteroidal anti-inflammatory medications).

While generally not life threatening, stomach and duodenal ulcers can be quite serious if not treated properly. More than 40,000 surgeries and as many as 6,000 deaths each year occur because of ulcers. About 1 in 10 Americans develops an ulcer during their lifetime.

Anatomy of an Ulcer

When we eat, food passes down the esophagus (throat) and into the stomach. There hydrochloric acid and pepsin (an enzyme) begin the digestive process. Next, food passes to the duodenum (small intestine) where the digestive process continues. An ulcer is an area of stomach or duodenum that has been destroyed by the digestive enzymes and stomach acid.

How H. pylori causes ulcers is not yet fully understood. Researchers do know the following:

  • H. pylori bacteria can live in the stomach because they produce an enzyme that stops the corrosive effects of stomach acid.
  • H. pylori's spiral shape allows it to get into the protective mucous layers of both the stomach and the duodenum.
  • H. pylori can also weaken the stomach and duodenum by attaching to cells. This further weakens the stomach and duodenum's defense system.
  • About 20% of people under the age of 40 have H. pylori in their digestive tracts, and 50% of people 60 or older have H. pylori.
  • Not everyone who harbors the H. pylori bacteria will develop an ulcer.
  • Being infected with H.pylori is a risk factor for developing stomach cancer.

An ulcer that goes untreated can cause several problems in the abdomen Problems include:

  • Internal bleeding
  • Perforation (a hole) in the stomach or duodenum allowing food and bacteria to spill into the abdomen and cause infection
  • Blockage of the opening between the stomach and duodenum due to chronic inflammation that leads to swelling and scarring

Discovering the Causes of Ulcers

The story behind the discovery of the H. pylori bacteria and its relationship to ulcers is an unusual one. In 1982, two Australian researchers, Drs. Barry Marshall and Robin Warren, detected H. pylori in the stomach lining of people suffering from gastritis. When further study demonstrated the presence of H. pylori in nearly 100% of patients with duodenal ulcers and 80% of people with stomach ulcers, Drs. Marshall and Warren proposed that H. pylori might be the cause.

When their hypothesis was met with a great deal of skepticism, Dr. Marshall ingested a teaspoonful of H. pylori bacteria. Within 24 hours, he developed severe gastritis. Further research by Dr. Marshall, Dr. Warren, and others established that H. pylori does in fact cause 50% of stomach ulcers and 90% of the much more common duodenal ulcers.

Of the 10-20% of ulcers that are not caused by H. pylori bacteria, most are caused by NSAIDs (nonsteroidal anti-inflammatory drugs), such as ibuprofen, aspirin, and naproxyn sodium. NSAIDs block the production of mucous in the stomach that protects the lining from the damaging effects of the stomach acid.

The Telltale Burn

The most common symptom of an ulcer is a chronic burning pain localized in the upper part of the abdomen. The pain is usually between the breastbone and the naval that can last from minutes to hours. Pain often recurs in the middle of the night, upon waking, and/or 2-3 hours after a meal. It may be relieved by eating or taking antacid medications such as Tums. Less common symptoms include:

  • Nausea
  • Vomiting (can be bloody or appear like coffee grains)
  • Loss of appetite
  • Loss of weight
  • Bloody or black stool (caused by bleeding from the ulcer)
  • Weakness (caused by bleeding from the ulcer)


It's important that ulcers be properly diagnosed because the symptoms common to ulcers can also be caused by a number of other conditions. In addition, ulcers caused by H. pylori and those caused by NSAID are treated somewhat differently.

Two most commonly used tests for diagnosing an ulcer:

  • Upper GI series—x-rays of the esophagus, stomach, and duodenum are taken after you drink a chalky substance that outlines the shape of the digestive tract. This test is 75-90% accurate in diagnosing ulcers.
  • Endoscopy—an examination of the esophagus, stomach, and duodenum via a small, flexible, camera-containing, tube-like instrument inserted through your throat. This test is approximately 95% accurate. During this test, tissue biopsies are taken of any suspicious lesion or ulcer.

Once an ulcer is diagnosed, a test for the presence of H. pylori is done to determine whether the ulcer is caused by H. pylori bacteria. Several methods exist for detecting H. pylori. A test for presence of H. Pylori bacteria may include a blood test to detect antibodies to the bacteria, a breath test that examines byproducts of the bacteria, or a laboratory analysis of the biopsied tissue sample. These tests differ in sensitivity for detecting the presence of bacteria in your system.

Removing the Offending Agent

Treatment involves removing the underlying cause of the ulcer and healing the ulcer. Dr. Stanley Rosenberg, gastroenterologist at Boston's Beth Israel Deaconess Medical Center explains.

"If NSAID use is suspected as the cause, especially if no H. pylori bacteria is detected, the patient will be directed to stop all NSAID use and to take a substitute medication, such as prescription strength Tylenol®.

However, if H. pylori is suspected as the cause, antibiotics are the first line of treatment. There are eight regimens approve by the US Food and Drug Administration for treatment of H. pylori infection. The most effective treatments employ multiple drugs—usually three or four in combination.

One common treatment involves taking two antibiotics to eliminate the bacteria (usually metronidazole and tetracycline) daily for two weeks, along with an acid suppressor and sometimes also a bismuth-containing stomach lining shield (Pepto-Bismol or other similar brands). This method works effectively over 90% of the time and works to kill the bacteria, heal the ulcer, and prevent recurrence. It may cause a number of side effects, including:

  • Stomach upset
  • Nausea
  • Diarrhea
  • Vomiting
  • Dizziness
  • Headache
  • Metallic taste in the mouth
  • Dark stools
  • Yeast infections in women

Two drug treatments such as omeprazole, which reduces stomach acid, in combination with amoxicillin (an antibiotic) may be less expensive, easier to tolerate, and causes fewer side effects than “triple” or “quadruple” drug therapy. However, two drug treatments are less effective (by up to 80%) than more complex three or four drug treatments

Healing the Ulcer

Dr. Rosenberg explains that a number of drugs can be prescribed that either reduce or temporarily eliminate stomach acid, while the antibiotics kill the bacteria in addition to soothing and healing the ulcer. These include:

Histamine H2 Blockers

These drugs, including Pepcid®, Zantac®, and Tagamet®, are given for up to 6-8 weeks. They suppress the amount of acid produced in the stomach by blocking histamine, a substance that causes the stomach to produce acid.

Acid Pump Inhibitors

Stronger than H2 blockers, these drugs, including Prilosec®, Aciphex®, Nexium®, and Protonix®, stop the stomach's production of acid by shutting down the stomach's acid pump. Such drugs are generally only prescribed for more severe ulcers, and only for a short period of time.

Mucosal Protective Drugs

These drugs, including Carafate® and Cytotec®, coat the stomach and duodenal lining, thus protecting the lining from stomach acid damage.

Finally, many patients also take antacids to neutralize stomach acid and/or Pepto-Bismol, which both coats the stomach and duodenum lining and helps fight the H. pylori bacteria.

Steering Clear of Ulcers

To prevent NSAID-caused ulcers, try to avoid using NSAIDs in large doses for long periods of time. Unfortunately, researchers don't yet know how to prevent the development of H. pylori bacteria in the digestive tract. Some recommended precautions are to wash hands thoroughly after using the bathroom and before eating, and to make sure to drink water from a clean source, since H. pylori is transmitted from person to person through close contact and exposure to body fluids such as vomit. An H. pylori vaccine is currently being studied.


The American College of Gastroenterology

National Institute of Diabetes & Digestive & Kidney Diseases


BC Health Guide

Health Canada


The American College of Gastroenterology website. Available at: http://www.acg.gi.org.

H. pylori and peptic ulcers. National Digestive Diseases Information Clearinghouse website. Available at: http://www.niddk.nih.gov/health/digest/pubs/hpylori/hpylori.htm.

International Agency for Research on Cancer. Schistosomes, liver flukes and Helicobacter pylori. IARC 1994; 61:177.

Uemura, N. Okamoto, S. Yamamoto, S. et al. Helicobacter pylori infection and the development of gastric cancer. N Engl J Med. 2001 Sep 13;345(11):784-9.

Last reviewed May 2008 by Daus Mahnke, MD

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.

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