Why does oesophageal cancer cause vomiting blood?

As a tumour changes the oesophageal lining, nearby tissue can become irritated and prone to bleeding. Swallowing or retching may disturb this fragile surface. Blood exposed to stomach acid can become dark and granular, while more recent bleeding may look bright red.

Vomiting blood can also have causes unrelated to cancer, including ulcers, severe inflammation or a tear after forceful retching. Its appearance cannot identify the cause or show how much blood has been lost.

Treat vomiting blood as an emergency symptom. Stop eating and drinking until a clinician advises you, especially if swallowing is difficult. Note the colour and approximate amount, whether clots are present, and any medicines such as blood thinners; take this information to emergency staff.

Medical teams may check circulation and blood levels, give fluids or other treatment, and use an endoscopic examination to locate and manage bleeding. Do not drive yourself if you feel weak, dizzy or confused.

Call emergency services immediately for bright-red blood, repeated vomiting, black stools, faintness, rapid breathing, confusion, chest pain or severe weakness. Even a single episode needs prompt assessment because bleeding can worsen without much warning.

Ask where the bleeding may be coming from, whether any medicine should be paused, how it will be treated, and which warning signs mean you should return immediately.