Blood in stool and coughing up blood: what to know

Coughing up blood usually appears mixed with mucus and may be bright red or rust coloured. It can occur with airway conditions such as bronchiectasis, chest infection, pneumonia, tuberculosis, a blood clot in the lung, or lung cancer. Blood that is vomited may be mistaken for coughed blood, so the action that brought it up matters.

Blood passed in stool has a different range of causes. Bright red blood may arise near the anus or lower bowel; black, sticky stool can reflect bleeding higher in the digestive tract. One symptom does not establish the cause of the other, and neither symptom should be self-diagnosed from colour alone.

Seek same-day medical advice and describe whether blood came after coughing, retching, or passing stool. Record its colour, approximate amount, frequency, mucus, breathlessness, chest pain, fever, abdominal pain, and bowel changes. Take your medicine list, including anticoagulants, to the assessment.

Do not smoke, drink alcohol, or take aspirin or anti-inflammatory pain medicine unless a clinician has told you to. Rest upright if breathing is uncomfortable, and do not drive yourself if dizzy or short of breath.

Call emergency services for more than streaks of blood, continuing bleeding, breathlessness, chest pain, a fast or irregular heartbeat, fainting, confusion, blue lips, severe weakness, or black stool. Emergency assessment is also needed if you cannot tell whether the blood was coughed up or vomited and you feel unwell.

Ask whether the blood is more likely from the lungs or digestive tract, which examination or imaging is needed, whether any medicine should be paused, and what symptoms require immediate return.