Peptic Ulcers, Varices, and Other Common Causes of GI Bleeding

Peptic ulcers and varices are two of the most common reasons for bleeding in the digestive system. Peptic ulcers are open sores in the stomach or the first part of the small intestine that can bleed when stomach acid damages the lining. Varices are swollen veins, usually in the esophagus, that may break open in people who have serious liver disease. Other causes can include tears from heavy vomiting or problems in the lower digestive tract. Only a doctor can find the exact source of the bleeding.

Bleeding from the gastrointestinal (GI) tract can appear in different ways. Some people notice bright red blood or material that looks like coffee grounds when they vomit. Others see black, tarry stools or bright red blood mixed with stool. In some cases the bleeding is slow and only shows up later as fatigue or low energy. The source may be high in the digestive tract (esophagus, stomach, or upper small intestine) or lower down. Understanding the more frequent causes helps patients talk with their doctors, but it does not replace a full medical evaluation.

Peptic ulcers as a frequent source of bleeding

Peptic ulcers form when the protective lining of the stomach or the first part of the small intestine (the duodenum) is weakened. Stomach acid then creates an open sore. According to Mayo Clinic, the two leading contributors are infection with Helicobacter pylori bacteria and long-term use of nonsteroidal anti-inflammatory drugs such as ibuprofen or aspirin. These factors reduce the mucus barrier that normally shields the lining from acid.

When an ulcer erodes into a blood vessel, bleeding can occur. The amount of blood loss varies. Some ulcers produce only small, slow leaks that may go unnoticed for a time. Others cause more obvious signs such as vomiting blood or passing black stools. Not every ulcer bleeds, and not every person with abdominal discomfort has an ulcer. A healthcare professional uses history, examination, and often endoscopy to determine whether an ulcer is present and whether it is the source of blood loss. You can learn more about how symptoms differ between upper and lower sources on our page about upper versus lower GI bleeding.

Esophageal and gastric varices

Varices are enlarged, fragile veins that develop when pressure rises in the portal vein system that carries blood through the liver. The most common background is cirrhosis, a condition in which long-term liver damage leads to scarring and restricted blood flow. According to Cleveland Clinic, these swollen veins most often appear in the lower esophagus and can also form in the upper stomach. Because their walls are thin, they can rupture and produce sudden, sometimes heavy bleeding.

Bleeding from varices may present with large amounts of bright red blood in vomit or with black, tarry stools. People with known liver disease are at higher risk, yet varices can occasionally be the first sign that significant portal hypertension is present. Not every person with cirrhosis develops varices that bleed, and the presence of varices does not automatically mean bleeding will occur. Doctors evaluate the size of the veins, signs of high pressure, and overall liver health before deciding on any monitoring or preventive steps. Additional information about emergency warning signs appears on our page about when GI bleeding is an emergency.

Other common sources of upper GI bleeding

Several additional conditions can produce blood loss from the upper digestive tract. Mallory-Weiss tears are linear breaks in the lining near the junction of the esophagus and stomach. They often follow forceful retching or vomiting and can cause noticeable bleeding that frequently stops on its own. Inflammation of the esophagus (esophagitis), often linked to acid reflux, may also lead to oozing or small amounts of blood. Erosions or irritation of the stomach lining (gastritis) from medicines, alcohol, or other factors can produce similar findings.

Less frequent but still important sources include abnormal blood vessels such as Dieulafoy lesions (a large artery that comes close to the surface) and, rarely, growths. The National Institute of Diabetes and Digestive and Kidney Diseases notes that peptic ulcers, esophageal varices, diverticular disease, gastritis, hemorrhoids, and cancer are among the conditions that can lead to GI bleeding overall. Each of these possibilities is evaluated through a combination of history, examination, and targeted testing rather than assumed from symptoms alone.

The following table summarizes several frequent sources of upper GI bleeding and the factors most often linked to them. It is intended only to illustrate patterns that clinicians consider; individual assessment always depends on the full clinical picture.

These associations help doctors prioritize tests, yet many people have more than one risk factor or none that are obvious at first. Trends over time and the person’s baseline health matter more than any single detail.

Lower GI sources that may also cause bleeding

Although peptic ulcers and varices belong mainly to the upper tract, other common causes of GI bleeding arise lower down. Diverticula (small pouches in the colon wall) can bleed when a nearby blood vessel is eroded. Inflammatory bowel conditions such as ulcerative colitis or Crohn’s disease may produce inflammation and open areas that bleed. Hemorrhoids and anal fissures are frequent reasons for bright red blood on the stool or toilet paper. These lower sources are discussed in more detail on our page covering GI bleeding from diverticulosis, IBD, and hemorrhoids.

Distinguishing upper from lower bleeding is not always straightforward from appearance alone. Black stools can result from either upper bleeding or certain foods and medicines. Bright red blood is more often lower, yet rapid upper bleeding can also produce it. Professional evaluation clarifies the location and the underlying process.

Medicines and other factors that may raise risk

Certain medicines can increase the chance of GI bleeding. Nonsteroidal anti-inflammatory drugs, low-dose aspirin used for heart protection, and blood-thinning agents all affect the lining or clotting ability. People taking more than one of these agents, or combining them with corticosteroids, face higher risk. Age, prior ulcer history, and concurrent H. pylori infection further influence the picture. Our page on medications that increase GI bleeding risk provides additional context for discussion with a clinician.

Alcohol use, smoking, and severe illness can also contribute in different ways. None of these factors guarantees that bleeding will occur, and many people who bleed have no clear single trigger. The decision about whether a medicine should be continued, adjusted, or protected with another agent is always individualized by a healthcare professional.

How doctors locate the source

Finding the exact origin of bleeding usually begins with a careful history and physical examination. Blood tests may show the degree of blood loss and help assess overall status. Endoscopy of the upper tract is often the first procedure when upper bleeding is suspected; it allows direct viewing and, in many cases, treatment of the bleeding site during the same session. Colonoscopy evaluates the lower tract. In selected situations imaging or other specialized studies are used. More detail appears on our page describing how doctors find the source of GI bleeding.

Repeat testing is sometimes needed when the first evaluation does not identify a clear source or when bleeding continues. A change from a person’s usual baseline values can be more meaningful than any absolute number. Only a licensed clinician can interpret findings in light of the full clinical context.

When medical evaluation is recommended

Any visible blood in vomit or stool, black tarry stools, dizziness, fainting, or sudden weakness warrants prompt medical attention. Even smaller amounts of bleeding that persist or that produce symptoms of anemia should be discussed with a healthcare professional. People with known liver disease, prior ulcers, or those taking blood-thinning medicines benefit from earlier evaluation if new symptoms appear. Emergency care is appropriate when bleeding is heavy, when there are signs of low blood pressure, or when consciousness is affected. You can review related warning signs on our page about symptoms of GI bleeding.

This information is educational. It does not diagnose any individual situation and cannot replace examination, testing, and personalized advice from a qualified clinician. Early professional assessment improves the chance of identifying the cause and selecting appropriate next steps.