Again, tons of things can switch up your stool—from chronic stress to medications to even tense pelvic floor muscles. But if your poop problems are new or different, Dr. Kupfer says, you need to get to the bottom of things, whatever the cause. The newness is key, she notes.
Another important point, Dr. Kupfer says, is whether your new digestive issues are happening alongside other concerning signs—especially blood in your stool, belly pain, or anemia (more on that below). IBS, for example, typically doesn’t cause bleeding or anemia, she explains.
4. Pounds are dropping for no reason.
Weight loss is often related to the colorectal cancer symptoms that can make it hard to eat, like diarrhea, stomach pain, or nausea. Plus, Dr. Biachi says, colorectal tumors can release hormones that can quash your appetite. In the JAMA review mentioned earlier, 15% of younger people reported appetite loss four to six months before their diagnosis.
Not feeling hungry and losing weight might be more likely once colorectal cancer spreads beyond the colon or rectum, but one study found that it was a symptom for 38% of people with earlier-stage colorectal cancer too. (People younger than 50 were just as likely as older adults to have some kind of weight loss.) But Del Valle, who was ultimately diagnosed with stage 4 cancer (it had spread to her liver), makes another point: She actually gained weight while bleeding heavily and assumed that was a sign that she didn’t have cancer.
So what’s a red flag? If you lose 10 pounds or 5% of your body weight over six months without trying (or, really, you experience any noticeable weight shifts) you should bring it up with a doc. There can be a lot of causes (diabetes, digestive disorders like IBD and celiac disease, and hyperthyroidism), but whatever the culprit, it’s important to get it checked out.
5. You’re showing signs of anemia.
Over time, bleeding from colorectal tumors, even if it’s not visible, may lead to anemia in some people (affecting 10% to 16% of younger folks). This means you don’t have enough oxygen-carrying red blood cells, and can lead to things like dizziness, headaches, shortness of breath, and just feeling constantly rundown. In some cases, though, you might only know you’re anemic when you get a blood test for something else entirely.

