Black Stool and Nausea: The Dangers, Possible Causes and When to Seek Medical Attention

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Black Stool

Melena or black, tarry stools, is a possible sign of bleeding somewhere in the digestive tract. This symptom can indicate a serious medical condition. On the other hand, there are potentially harmless reasons for black-colored stool, such as what a person has been eating — some foods or supplements can cause a discoloration of the stool. Certain things that can cause a false color to the stool are iron tablets, multi-vitamins or even certain foods such as blueberries or licorice. Often a product that is used to treat stomach illnesses, known as bismuth subsalicylate, can also cause a darkening of the stool.

But when black stools are caused by something other than food or medication it can be a serious matter. One of the most common causes of black stools is blood from the gastrointestinal (GI) wall. This is often caused by an ulcer that has started bleeding within the lining of the esophagus or stomach. This is a serious condition and you should get help immediately if you discover blood within your stools or have black, tarry stools.

The most common cause of an ulcer is a bacteria called Heliobacter pylori. It can be easily eliminated with a course of antibiotics. Other than bacteria some people can develop a GI bleed from taking medication such as NSAID’s. Aspirin is an example of this type of medication. It can hurt the lining of the stomach, causing it to bleed. Other than bacteria, the inflammation of the stomach wall can be irritated by certain foods or alcohol leading to a condition known as gastritis. This can also lead to bleeding of the GI tract, producing black stools.


Nausea is a very common symptom of many medical conditions. When a person does have nausea, this can mean that the underlying cause of it is resulting in an irritation to the lining of the stomach or intestine.

Some medical conditions that cause nausea conclude pregnancy, food poisoning, panic attacks, ulcer, gastritis, diabetic ketoacidosis, drug allergy, alcohol and drug abuse, or kidney disease. Therefore it is possible to see that nausea is very common and cannot easily be attributed to one specific medical condition.

Conditions with Melena and Nausea

When these conditions occur together, there are at least 23 medical conditions that can have these two symptoms. They range from mild conditions such as an ulcer to a more severe condition such as bowel impaction. However it does not mean that only conditions affecting the gastrointestinal system will cause these symptoms within every person.

Other conditions such as a bacterial infection, medication toxicity, or long term kidney disease can cause both black stool and nausea within someone.

The Treatment

If the person does have black stools, they are urged to quickly see a doctor as if they leave it for too long, this can a result in a variety of complications. In situations where the person is experiencing nausea for more than two to three days, they should also book an appointment to see their family physician.

Treatment of this disorder will involve taking care of the underlying cause of the black stool and nausea in the first place. For example, if the person has an H. pylori infection, giving an antibiotic can remove its presence. There is no specific treatment that can remove the black stool or nausea until the underlying cause has been identified and treated.

References Black Stool Symptom Search

US National Library of Medicine, MedlinePlus: Bloody or tarry stools

Merck Manual: Nausea and Vomiting