What does it mean if I see blood in my poop?

First, don’t be scared. At least for the youngest, the reason is not always serious. It could be hemorrhoids, it could be a medication you’re taking, it could be colitis, and (usually in older people) it could be cancer.

If you do see blood, it is most likely red, but sometimes it can be black. Blood that mixes with stomach acid turns black and means the bleeding is coming from the upper part of the GI tract (the stomach or duodenum). If you see stools that are unusually dark or black in color (called melena), or that look like tar, it may be blood that has passed from the stomach to the intestines. A stomach ulcer or irritation is commonly the culprit. Since this can be serious, see your doctor right away.

Now, if the blood is red, first a question: is it a streak on the outside of the bowel movement, or blood in the toilet water, or blood mixed with the stool (poop)?

If there is a streak on the outside of the bowel movement, it is often caused by external hemorrhoids. There may be pain associated with this type of bleeding, which is commonly seen with constipation or large stools.

If there is blood in the stool and perhaps a little dripping in the toilet water, this may be internal hemorrhoids, which are often painless. These are also associated with constipation and hard stools, but also with diarrhea and straining.

You should confirm these conditions with your doctor, but hemorrhoids are probably the “best case scenario” and are easily (most of the time) treated. Occasionally a tumor (such as cancer) will also present in this way. Anyone over the age of 50 should be screened for colon cancer.

If the blood mixes with the stool but you have no other symptoms, cancer is once again a possibility, along with colitis, diverticulitis, and the effects of medications. If you are taking aspirin, ibuprofen, naproxen, or other anti-inflammatory or blood-thinning medication, it is recommended that you discontinue these medications and consult your physician. If you have an infection or inflammation (such as diverticulitis, colitis, or inflammatory bowel disease), you probably have some type of symptom in addition to bleeding: abdominal discomfort, cramps, gas, bloating, diarrhea. However, some patients only have bleeding. Either way, having blood mixed with your stool is usually serious and should be evaluated right away.

Sometimes people get diarrhea (with or without blood) after taking an antibiotic. This may be due to antibiotic-associated colitis (Clostridium difficile colitis, “c. diff”) and requires immediate attention. Report these symptoms to your doctor right away, as you will likely need a second antibiotic to treat this condition. However, certain antibiotics can cause diarrhea on their own without causing c. diff colitis

Finally, sometimes red dye or red food can look like blood, but it isn’t. Beets, red Jello, and other red foods are known to be mistaken for blood, but don’t attribute the red discoloration to food unless you’re sure.

Copyright 2010 Cynthia J Koelker MD