Hematemesis (Vomiting Blood)

Nausea and vomiting are common side effects of many cancer treatments. But blood in your vomit (hematemesis) might be a sign of a more serious problem. Learn what it means if you have blood in your vomit and what to do if this happens.

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What is hematemesis?
What cancers and cancer treatments cause hematemesis?
Is vomiting blood always serious?
Is a small amount of blood in vomit normal?
When to talk to your doctor about blood in your vomit
Learn more

What is hematemesis?

Hematemesis is when you have blood in your vomit (emesis).

It could look like:

A small amount of blood streaking in your vomit
Bright red or dark brown vomit
Vomit that looks like coffee grounds

This may be a symptom of internal bleeding, which can be serious.

Hematemesis is a sign of bleeding somewhere in your upper gastrointestinal (GI) tract, which includes your stomach, esophagus, and the first part of your small intestine (duodenum). It can happen when these organs are damaged by disease, treatment, or nausea and vomiting.

Hematemesis can be worse if you are at higher risk for bleeding because of low platelets (thrombocytopenia) or other problems.

What cancers and cancer treatments cause hematemesis?

You might have blood in your vomit for many reasons including your cancer, cancer treatment, or some other medical problem not related to cancer.

Cancers most likely to cause hematemesis

Some cancers might cause you to vomit blood, including:

Esophageal
Stomach
Small intestine
Liver

Esophageal, stomach, and small intestine cancer: These cancers can damage your upper GI tract and grow through the lining of these organs (direct invasion). This may cause hematemesis.

Liver cancer: When cancer damages your liver, this damage can block the normal flow of blood and cause it to back up into the veins of your esophagus. These veins may swell and tear, leading to bleeding. (You might hear the term varices, which means swelling of the veins.)

Liver cancer can also lower your liver’s ability to make coagulation factors, causing you to bleed more easily. (Coagulation factors are proteins that help your blood clot.)

Cancer treatments most likely to cause hematemesis

Side effects of some cancer treatments might increase your risk of vomiting blood. This includes:

Some chemotherapy (chemo) medicines
Radiation therapy to your chest, abdomen, or liver
Total body irradiation (TBI)
Radiation to your brain

Chemotherapy: Some chemo medicines can cause severe nausea and vomiting. This could damage the lining of your stomach or esophagus and lead to bleeding. Some of these medicines can also lower your platelet count (thrombocytopenia) and increase your risk of bleeding.

Radiation therapy: Treatment to your chest, abdomen (belly), liver, or whole body (total body irradiation, or TBI) can damage your esophagus and stomach, increasing your risk for hematemesis.

Radiation to these areas, or to your brain, can cause severe nausea and vomiting. This further increases your risk of bleeding. These treatments can also lower your platelet count, making it harder for your blood to clot and increasing your risk of bleeding even more.

Supportive care medicines

Some medicines used to manage side effects from cancer or cancer treatment can lead to hematemesis. These include:

Oral bisphosphonates, for bone loss from cancer or treatment. These might damage the lining of your esophagus or stomach and lead to bleeding.
Nonsteroidal anti-inflammatory drugs (NSAIDs), like ibuprofen and naproxen, as well as aspirin, to manage pain. These can damage your stomach lining and can also interfere with how well your platelets work.
Anticoagulants, to treat and prevent blood clots. These lower your blood’s ability to clot and increase your risk of bleeding.

Is vomiting blood always serious?

Any amount of blood in your vomit is cause for concern. The cause of the bleeding might heal on its own, but it might mean you have a serious and even life-threatening problem. Contact your doctor or cancer care team right away for any amount of blood in your vomit.

Is a small amount of blood in vomit normal?

No. It isn’t normal to have any blood in your vomit. Any amount of blood should be reported to your doctor or cancer care team so they can figure out what needs to be done.

When to talk to your doctor about blood in your vomit

Vomiting blood can be serious and even life-threatening for some people. It needs to be checked out right away to keep it from getting worse.

Contact your doctor or cancer care team right away if you have:

Any amount of blood in your vomit
Vomit that looks like coffee grounds
Burning or pain in your chest or stomach
Red or black stools (poop)

Call 911 or go to the emergency room if you:

Throw up bright red blood
Have chest pain or trouble breathing
Feel weak or dizzy
Are faint or confused

Learn more

Managing Cancer-related Side Effects

Written by
References

The American Cancer Society medical and editorial content team

Our team is made up of doctors and oncology certified nurses with deep knowledge of cancer care as well as editors and translators with extensive experience in medical writing.

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Kamboj AK, Hoversten P, Leggett CL. Upper Gastrointestinal Bleeding: Etiologies and Management. Mayo Clin Proc. 2019;94(4):697-703. doi:10.1016/j.mayocp.2019.01.022

Rockey DC. Causes of upper gastrointestinal bleeding in adults. UpToDate. 2024. Accessed at https://www.uptodate.com/contents/causes-of-upper-gastrointestinal-bleeding-in-adults on June 12, 2025.

Last Revised: July 17, 2025

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