The most telling signs of a bleeding ulcer are visible changes in your stool or vomit. Black, tarry stools or vomit that looks like dark coffee grounds indicate blood that has been partially digested in your stomach. Bright red or maroon blood in your stool, or red blood in your vomit, signals a more active, faster bleed. But not all bleeding ulcers announce themselves this dramatically. Some bleed slowly enough that you never see blood at all, and the first clue is unexplained fatigue or dizziness from gradual blood loss.
What a Bleeding Ulcer Looks Like
A peptic ulcer is an open sore on the lining of your stomach or the upper part of your small intestine. Most ulcers cause a burning or gnawing pain in the upper abdomen, but they don’t always bleed. When one does, the blood has to go somewhere, and the direction it travels determines what you’ll notice.
If blood pools in your stomach and you vomit it up, it often looks like coffee grounds: dark, grainy, and brown-black. That color comes from stomach acid partially breaking down the blood. If the bleeding is heavy and fast, the vomit may contain fresh red blood instead. Both warrant immediate medical attention.
Blood that moves the other direction, down through your intestines, produces a distinctive stool. The medical term is melena: stool that is black, sticky, and tarry, with a particularly strong smell. The dark color results from blood being digested as it passes through your gut. In cases of very rapid bleeding, you may see red or maroon blood mixed directly into your stool, meaning the blood is moving through too quickly to be broken down.
Subtle Signs of a Slow Bleed
Not every bleeding ulcer produces obvious blood. When an ulcer oozes slowly, the blood loss can be so gradual that your stools look normal and you never vomit. This is called occult (hidden) bleeding, and it’s easy to miss for weeks or even months. The damage shows up in other ways.
The most common consequence of slow bleeding is iron-deficiency anemia. Your body loses red blood cells faster than it can replace them, and your iron stores drop. You may feel unusually tired, short of breath during normal activities, lightheaded when standing up, or notice your skin looking paler than usual. Some people develop chest pain or a rapid heartbeat because the heart has to work harder to circulate less oxygen-rich blood. These symptoms often get chalked up to stress, poor sleep, or aging before anyone thinks to check for internal bleeding.
Standard stool tests designed to detect hidden blood are only about 58% sensitive, meaning they miss a significant number of cases. If your doctor suspects a slow bleed based on your symptoms or blood work showing low iron, they’ll typically move to a more definitive test rather than relying on a stool sample alone.
What Causes an Ulcer to Bleed
Two culprits are responsible for the vast majority of peptic ulcers: a bacterial infection called H. pylori and regular use of NSAIDs like ibuprofen, naproxen, or aspirin. In one study of 217 patients with gastric ulcers, 85% had evidence of H. pylori infection and 30% had used NSAIDs in the prior four weeks.
Having an ulcer doesn’t guarantee it will bleed, but certain factors sharply increase the risk. NSAID use raised the odds of bleeding nearly sevenfold in that same study. Being over 65 increased the odds about 3.4 times. NSAIDs are particularly dangerous because they suppress the protective mucus layer in your stomach while also thinning your blood, creating a double threat. If you take a daily aspirin for heart health or regularly use ibuprofen for joint pain, you’re in a higher-risk category even if you’ve never had ulcer symptoms before.
Alcohol and smoking don’t directly cause ulcers, but both slow healing and can irritate an existing sore enough to trigger bleeding.
When Bleeding Becomes an Emergency
Bleeding ulcers are the most common serious complication of peptic ulcer disease, accounting for about 73% of all ulcer complications in the United States and contributing to roughly 10,000 deaths per year. Most of those deaths involve heavy, rapid blood loss that leads to shock.
Your body holds about five liters of blood. Losing around 15% of that volume (roughly 750 mL) causes a noticeably faster heart rate, even at rest. At 30% loss, your blood pressure drops when you stand up and you may feel faint. Beyond 40%, blood pressure falls even while lying down, and you may experience cold, clammy skin, confusion, rapid breathing, and very little urine output. These are signs of hypovolemic shock, and they require emergency treatment.
You should treat any of the following as urgent: vomiting blood of any color, black or bloody stools, sudden sharp abdominal pain that doesn’t let up, feeling faint or confused, or a heart rate that feels unusually fast while you’re sitting still. Don’t wait to see if it improves on its own.
How a Bleeding Ulcer Is Diagnosed
The primary diagnostic tool is an upper endoscopy, a procedure where a thin, flexible tube with a camera is passed through your mouth into your stomach and upper intestine. This is typically performed within 24 hours of arriving at the hospital. The camera allows the doctor to see the ulcer directly, identify where the bleeding is coming from, and assess how likely it is to bleed again.
What the doctor sees through the scope matters a lot for predicting your outcome. An ulcer with active arterial spurting has about a 90% chance of rebleeding without treatment. A visible blood vessel in the ulcer base carries a 50% rebleeding risk. An ulcer with a clean base, meaning no visible vessel or clot, has only about a 3% chance of rebleeding. These findings directly determine how aggressively the bleeding needs to be treated.
The endoscope isn’t just diagnostic. If the doctor finds active bleeding or a high-risk vessel, they can treat it during the same procedure using clips, heat, or injection to stop the bleed. This dual role is why endoscopy is the standard of care rather than imaging scans or blood tests alone. Before the procedure, the stomach is often cleared of blood and clots to give the camera a better view.
What Recovery Looks Like
After the bleeding is controlled, treatment shifts to healing the ulcer itself and preventing it from coming back. If H. pylori is the underlying cause, you’ll take a combination of antibiotics and acid-reducing medication for one to two weeks to clear the infection. If NSAIDs caused the ulcer, stopping or switching those medications is essential, and you’ll take acid-suppressing drugs to give the ulcer time to heal, typically over four to eight weeks.
During recovery, you may need iron supplements if the bleeding caused anemia, and follow-up blood tests to confirm your levels are improving. Some patients need a repeat endoscopy after several weeks to verify the ulcer has fully healed, especially if the ulcer was large or in a location associated with higher risk.
The good news is that once the cause is addressed, most peptic ulcers heal completely and don’t return. The critical step is identifying what triggered the ulcer in the first place, whether that’s an ongoing infection, a medication you take daily, or both, and eliminating that trigger rather than simply treating the symptoms.