Black stool while taking aspirin

Melaena is stool that is jet black, sticky or tar-like and often unusually strong-smelling. It can occur when blood from the stomach or upper intestine is digested as it moves through the bowel. Aspirin makes platelets less able to form a clot and can irritate the stomach lining, so bleeding from gastritis or an ulcer may be more difficult to stop.

Not every dark stool contains blood. Iron tablets, bismuth-containing remedies and some foods can darken stool, but appearance alone cannot safely distinguish these causes from bleeding. A clinician may review medicines, examine you, order blood tests or arrange investigation of the digestive tract.

Contact a healthcare service promptly for black, tarry stool, even if you otherwise feel well. State that you take aspirin and describe when the stool changed, its texture, any abdominal discomfort, dizziness or vomiting. Have the aspirin container and a list of all medicines available, including ibuprofen, naproxen, anticoagulants, steroids, iron and stomach remedies.

Do not take extra aspirin for pain while awaiting advice, and do not substitute another anti-inflammatory medicine. If aspirin was prescribed to prevent a heart attack or stroke, obtain urgent clinical instructions about the next dose rather than making a prolonged change yourself.

Call emergency services for black stool accompanied by fainting, severe dizziness, confusion, cold clammy skin, rapid breathing, marked weakness, chest pain or breathlessness. Vomiting blood or material resembling coffee grounds is also an emergency sign.

Severe or increasing abdominal pain, repeated black stools, or visible red blood needs urgent assessment. Do not drive yourself if you feel faint or weak; sit or lie somewhere safe while help is arranged.

Discuss whether testing for anaemia, an ulcer or Helicobacter pylori is appropriate; whether any medicine combination increased bleeding risk; and when aspirin should be resumed if it was held. Ask which stomach-protection or pain-treatment plan is suitable for you rather than using an over-the-counter substitute.