11. Shortness of Breath
Along with anemia, having troubles breathing can be another sign that internal bleeding is occurring. Particularly, it’s an indication of a slow bleed, which commonly occurs with colon cancer as a result of ruptured cancerous polyps.
In speaking with Reader’s Digest, Patricia Raymond, M.D., explains why this symptom occurs: “If you aren’t bleeding aggressively or vomiting blood, your body puts more plasma in the blood without making more iron or red blood cells,” she says, “which prevents you from losing blood in large volumes but reduces blood’s ability to carry oxygen, which is why you might notice shortness of breath.”