What should you know about black and sticky stool?

Black, sticky, tar-like stool can signal bleeding in the upper digestive tract and needs prompt medical assessment, especially with weakness, dizziness, pain or vomiting blood. The medical term is melaena. Blood exposed to digestive juices can make stool look black and give it a sticky, tar-like texture and strong smell. Do not assume that a dark bowel movement is harmless if it is genuinely tarry.

Bleeding can come from the oesophagus, stomach or the first part of the small intestine. Possible causes include a peptic ulcer, inflammation of the stomach lining such as gastritis, or infection with Helicobacter pylori. Some medicines, including anti-inflammatory painkillers and blood thinners, can increase bleeding risk. Iron tablets, bismuth-containing medicines and some dark foods can also turn stool dark, but they do not usually create the classic tarry consistency. A clinician may need to review your medicines, examine you and arrange blood tests or other investigations to identify the source.

If the stool is black and sticky rather than simply dark, contact a healthcare professional promptly for advice, even if you feel well. Keep a list or photograph of medicines and supplements you use, including aspirin, anti-inflammatory painkillers, iron and bismuth products. Do not take extra aspirin or anti-inflammatory painkillers unless a clinician has told you to. Do not stop a prescribed blood thinner on your own; ask urgently for individual instructions.

Seek emergency care now if black tarry stool occurs with fainting, marked dizziness, confusion, severe weakness, a rapid heartbeat, shortness of breath, severe abdominal pain, vomiting blood or vomit that looks like coffee grounds. These symptoms can accompany significant blood loss. Do not drive yourself if you feel faint or unsteady. While waiting for help, avoid alcohol and do not eat or drink if you are being assessed for an emergency unless the treating team advises otherwise.

Ask what could explain the stool appearance, whether any medicine should be changed safely, and whether you need tests to look for blood loss or a digestive-tract source. Tell the clinician when it began, how often it has happened, whether it is sticky or unusually smelly, and whether you have pain, nausea, dizziness or vomiting. Mention previous ulcers, gastritis, Helicobacter pylori infection, liver disease and any recent use of anti-inflammatory painkillers.