The Difference Between IBS-C and Chronic Constipation

Medically Reviewed by Jennifer Casarella, MD on August 28, 2022
2 min read

If you find yourself straining to have normal, regular bowel movements for weeks or months on end, something may be going on inside your body. If you poop no more than twice a week, you’re constipated. And if the situation lasts a long time, at least 3 months, you have chronic constipation.

But your chronic constipation could be a sign of a look-alike digestive illness called irritable bowel syndrome with constipation, or IBS-C. The symptoms for the two disorders overlap so much that doctors aren’t completely sure if they’re related conditions or entirely different ones.

If you have either IBS-C or chronic constipation, you might:

  • Need great effort to move your bowels
  • Make lumpy, hard stools
  • Feel like something is blocking your bowel movement
  • Don’t feel like you’ve emptied all your stool in the bathroom     
  • Deal with gas and bloating

Some symptoms of IBS-C usually don’t happen with chronic constipation alone. For example, with IBS-C you may:

  • Often have stomachache and discomfort that goes away after you poop. The pain can be very bad.
  • Poop normally or have loose, watery stools between bouts of constipation
  • Have nausea

You may know that too little fiber in your diet can stop up your bowels. But chronic constipation can have more serious roots, including intestinal blockages. The causes of IBS-C are less well understood, but doctors have a few clues.

Chronic constipation can be caused by:

  • Drugs for depression, pain, Parkinson’s, heart disease, and other conditions
  • Type 2 diabetes or thyroid problems
  • Medical problems that cause high or low levels of calcium in your blood
  • Spinal cord injuries
  • Colorectal problems like cancer or narrowing of your rectum

Causes of IBS-C include:

  • Slow passage of food through your intestine
  • Problems with bacteria, hormones, or chemicals in the intestines
  • Miscommunication between your brain and your bowel
  • Family history of IBS-C or other digestive disorders

There is no specific test that can pinpoint what’s causing your constipation. Your doctor will start with your medical history and a physical exam.

They may give you a blood test to see if thyroid issues are behind your constipation. You may need to give a stool sample so your doctor can check for a bacterial infection. A physical exam can show if you’re dealing with muscle or structural problems with your rectum. You also may have special X-rays, CT scans, or a colonoscopy to see if stool is able to pass through your colon or rectum the way it should.

There’s no test for IBS-C, so they’ll gather as much information as possible to rule out other causes. Things like unexplained weight loss, taking antibiotics, and blood in your stool could mean that other medical problems are part of the problem.

Your doctor may use a set of symptoms to decide if you have IBS-C. The checklist can include changes in how often you poop, severe belly bloating, and feeling better after a bowel movement.