A person with IBS has a digestive system that does not function properly, even though nothing appears to be medically wrong. This state of affairs can be quite frustrating if you suffer from abdominal pain, diarrhea or constipation. You may wish for more certain answers about the cause of your symptoms, but the reality is they are not always available. Going down the rabbit hole of the internet will quickly turn up a long list of scary conditions that have these symptoms, too. Although it’s natural to be concerned about these other possibilities, especially if you’ve known someone with inflammatory bowel disease or some sort of cancer, I’d like to help settle your nerves with this post.

Before going on, I'd like to acknowledge that IBS is plenty serious itself for many people. I'm not trying to down-play that at all. Dismissing symptoms as "just IBS" is not OK. IBS affects lives, relationships and work, severely at times. There are still times when we need more clarity about the meaning of our symptoms.

Let’s talk about 8 “alarm” signs and symptoms that merit concern and sometimes additional investigation. None of these automatically means trouble beyond IBS, but your healthcare provider will take them into account during your evaluation. Your entire symptom pattern and all of your clinical data will be considered. On the other hand, if you DON'T have any of these alarm symptoms, it may be perfectly reasonable for your doctor to give you a diagnosis of IBS without further investigation. (Note: This is a general discussion, not medical advice. Please talk your concerns over with your own health care provider.)

Know these signs that it's not IBS; important talking points to discuss with your health care provider.

Rectal bleeding. A little bright red blood on the toilet tissue is rarely concerning. Of more concern would be blood that comes from higher up in the gastrointestinal tract, which may appear as brown or black streaks in the stool. Pink or red toilet water after a bowel movement can indicate blood in the stool as well, but don’t let beet eating or menstrual blood fool you. Those are harmless.
Change in bowel habits over age 50. Are you one of those people that used to be able to eat anything and never had any abdominal or bowel complaints when you were younger? Although IBS can sometimes be a new problem in the second half of life, a change of bowel habits over age 50 should be very thoughtfully evaluated.
Unexplained weight loss. If you’ve been cutting foods out of your diet to manage your IBS, any weight loss you may have experienced really can’t be considered “unexplained,” can it? But if you have mysteriously lost more than a few pounds, even though you haven’t changed your diet, report it to your doctor.
Unexplained anemia or other lab work revealing low levels of any nutrient. These can be associated with malabsorption of nutrients and are sometimes seen in medical conditions that affect the gastrointestinal tract. (Vitamin D may be an exception here. While low vitamin D blood levels can certainly affect people with gastrointestinal conditions, it is not a nutrient that naturally occurs in food. Low vitamin D levels are common, and not necessarily a sign of malabsorption.)
Family history of colon cancer, Crohn’s disease, ulcerative colitis, celiac disease or ovarian cancer. If a close relative has one of these conditions, do make sure your doctor is aware. Intellectually, you may realize that family history is only one risk factor for these diseases, and that only a small fraction of people with affected relatives will get a similar diagnosis. But when you've seen the impact these diseases have had on a loved one they are hard to forget. I’ve noticed that my patients with these family histories (understandably) experience quite a bit more anxiety about their abdominal and bowel symptoms than other patients do. If such worries are interfering with your health and happiness, consider seeing a mental health care professional for assistance with managing anxiety. Since anxiety itself may amplify your symptoms, you might need a little help breaking out of this vicious cycle.
Fever. If you experience fever during a bout of your IBS symptoms, call your doctor.
Anal or rectal problems. Anal abscesses and fistulas can be signs of inflammatory bowel disease. Hemorrhoids, while uncomfortable, are more common and not necessarily a sign of a disease. Anal fissures can be seen in inflammatory bowel disease, but can also simply develop due to straining with diarrhea, constipation or hard, dry stools.
Poor growth in children. While gastrointestinal disease is just one possible explanation for poor growth in children, it should be considered as part of an evaluation.

Remember, don’t try to diagnose yourself. Bring your concerns to a licensed healthcare provider, particularly any of these alarm symptoms, to review your diagnosis of IBS. If you are female, see a gynecologist as part of your evaluation as well, to rule out problems related to your reproductive system as well.