You learn you’re anemiciStock/Dean Mitchell
A diagnosis of anemia may be the first sign that you’re bleeding internally, even if you haven’t seen any signs of it. “If a woman is menstruating, anemia is less likely to be followed up with additional tests to see if it could be something else, like colon cancer,” says Randall Holcombe, MD, chief medical officer, cancer, at Mount Sinai Health System in New York City. “If a man is anemic, you assume he’s bleeding from somewhere.” It’s not uncommon for people to bleed internally for up to six months before anything shows up in the stool, says Patricia Raymond, MD, a fellow at the American College of Gastroenterology. If you experience any signs of anemia, such as fatigue or dizziness, see a doctor.
You can’t catch your breathiStock/Geber86
Another side effect of a slow internal bleed is shortness of breath. 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, says Dr. Raymond, 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.
You feel bloated or crampyiStock/BernardaSv
“If things are starting to get blocked and backed up in the colon, you may experience bloating,” says Dr. Holcombe. If you’re feeling a little puffy or crampy, there are many other factors besides colon cancer that may be to blame, but if stomach symptoms persist, see your doctor. If you start to notice a constant pain in the right side of your abdomen, that may mean the disease in the later stages and has spread to the liver, he says.
You have severe constipationiStock/gpointstudio
A bout of constipation here and there is probably nothing to worry about, but if it becomes severe and persistent, it could signal colon cancer. “This is something that is suggestive of some sort of obstruction, and if it seems to be there all the time you should get it checked out,” says Dr. Holcombe. (Here are some other reasons you could be constipated).
You pass skinny stooliStock/omersukrugoksu
Pay attention to what’s in the toilet, even if you don’t see blood. If your stool consistently takes on a very narrow or skinny shape when it was previously chunkier, that could point to a restriction in the colon caused by polyps, says Dr. Raymond. Persistent diarrhea may also signal a problem.
Your stool is a weird coloriStock/smusselm
Bleeding from the rectum may not always come in the form of bright red blood, says Dr. Holcombe. Dark, tarry stools are a sign there’s probably some blood in there, and while it could be caused by something less serious, like an ulcer, this can also be a sign of colon cancer, he says.