Sussing Out Colitis and Diverticulitis Symptoms

Colitis, an inflammation of the large intestine, and diverticulitis, an infection of small pouches usually in the large intestine, are ailments that can have similar symptoms. But they're very different conditions. Here's what you need to know.

Though diverticulitis and colitis both involve parts of the digestive system, their symptoms are generally so specific that it shouldn't take your doctor long to rule out one or the other.

By comparison, "colitis usually has a long, gradual onset marked by diarrhea and blood," and "diverticulitis usually comes with an abrupt onset of pain," says gastroenterologist Neil Stollman, MD, chief of gastroenterology at Alta Bates Summit Medical Center in Oakland, California, and associate clinical professor of medicine at the University of California San Francisco.

Read more: Best Foods to Eat With Ulcerative Colitis, an IBD

Abdominal pain: Pain and discomfort are hallmarks of both diseases, though they're felt in different ways. With diverticulitis, discomfort can vary from tenderness to severe pain. You'll typically feel the discomfort on the lower left side of your abdomen, according to the National Library of Medicine.

However, as Mayo Clinic points out, people of Asian heritage may feel it more acutely on the right side of the abdomen. The tenderness tends to be continuous over a period of days, says Mayo Clinic.

With colitis, abdominal pain may be continuous or could appear and then disappear, according to the National Library of Medicine. You might experience pain in the form of cramps, states the Mayo Clinic.

Diarrhea and constipation: Diarrhea is the most common symptom of colitis — it may even wake you out of your sleep — and it can be bloody and may include pus, according to the Mayo Clinic. Constipation is also possible, according to Johns Hopkins Medicine. People with colitis may also feel an urgent need to poop, yet not be able to, says Mayo Clinic. Rectal spasms are also possible. While you could experience constipation with diverticulitis, diarrhea is less likely, Mayo states.

Rectal bleeding: With diverticulitis, rectal bleeding is rare, according to the National Library of Medicine. On the other hand, rectal bleeding and rectal pain are common in some types of colitis, according to Harvard Health, and you may see blood in your stool. The blood will be bright red or maroon-colored, not dark red. If you are bleeding rapidly, it's crucial to seek emergency care immediately.

Bloating and fever: Both diverticulitis and colitis can cause bloating and fever, according to the National Library of Medicine.

Other symptoms: Some specific symptoms set the two diseases apart. With diverticulitis, men may suffer from urinary symptoms if an inflamed part of the intestine rubs up against the bladder, according to Harvard Health. These symptoms can include frequent urination, urgent urination and discomfort. Nausea and vomiting are also more characteristic of diverticulitis.

Other symptoms of colitis include weight loss, loss of appetite, anemia (not having enough red blood cells) and — less commonly — joint pain or soreness, eye irritation and rashes, according to the National Institute of Diabetes and Digestive and Kidney Diseases.

Read more: Foods to Eat With Diverticulitis

Schedule a doctor's visit, Mayo Clinic suggests, if you have these symptoms of colitis:

• Abdominal pain
• Blood in your stool
• Diarrhea that continues even after you treat it with over-the-counter drugs
• Diarrhea that wakes you up
• A fever that lasts for more than a day or two without explanation

Schedule a doctor's visit if you have these symptoms of diverticulitis: Continuous abdominal tenderness or pain without an obvious reason, especially if you also have a fever and constipation or diarrhea.

Keep in mind that any unusual signs should prompt a visit to your doctor. Don't try to diagnose these conditions on your own, warns Dr. Stollman.