Medical Causes of Chronic Constipation

Medically Reviewed by Minesh Khatri, MD on March 12, 2023
3 min read

If you’ve been constipated for a while, you should find out why.

If there’s a problem with how your lower intestinal tract (colon, rectum, and anus) is working, you have “functional constipation.” But if that's not the case, you could have “secondary constipation” -- that’s when it’s brought on by a medical problem or a medication you take.

Some medications can cause constipation as a side effect. They include:

  • Heartburn medications like aluminum or calcium antacids
  • Certain depression medications
  • Calcium channel blockers that control blood pressure
  • Diuretics (water pills)
  • Drugs to lessen or treat muscle spasms in your gut
  • Iron pills to treat some kinds of anemia
  • Epilepsy medications
  • Painkillers such as morphine, codeine or other opioids

Iron pills are also often used. If your doctor thinks it’s something you’re taking, talk to them about your other options.

You may have something else going on that’s slowing down your digestion. Several conditions are known to cause such problems:

Irritable bowel syndrome (IBS) causes belly pain, gas, bloating, and a change in bathroom habits. If you have IBS with constipation (IBS-C), you may notice that your symptoms flare and then normal bowel habits return. Sometimes, bouts of diarrhea or loose stools happen, too.

Diabetes: Constipation is common for people with this condition. It’s thought that diabetes may affect nerves in the colon, which can slow down the movement of stool.

Hypothyroidism: This happens when your thyroid gland doesn’t make enough hormones. This can slow down many of your body functions, including your bowels.

Neurological diseases: Constipation is more common in people with multiple sclerosis, Parkinson’s disease, spinal injuries, and the neuromuscular disease muscular dystrophy. People with these conditions can have problems relaxing muscles in the pelvic floor which makes it hard to push stool out. Or their colons may work more slowly, leading to fewer bowel movements.

Colon cancer: Constipation and/or a change in the color or shape of your stool can be a sign of this cancer. If it’s red, maroon, or very dark, you could have blood in your stool.

Crohn’s disease: This causes irritation and swelling in any part of the digestive tract. If it happens in your rectum, you may get constipated.

Diverticulosis: This happens when small pouches bulge out from the wall of your colon. Some people don’t have symptoms. But you may have bloating, cramping, diarrhea, and constipation. These symptoms may get worse if the pouches get swollen or infected. That’s a problem called diverticulitis.

Pregnancy: About 2 in 5 pregnant women get constipated. It’s usually more of a problem during the first few months. When you’re expecting, your body makes more of the hormone progesterone. It acts as a muscle relaxant. That slows down the natural movement of your bowels, so waste doesn’t move as fast through your system.

Talk to your doctor if you think you may have one of these conditions. Make sure they’re aware of all your symptoms. You’ll probably need tests to find out what’s going on. No matter the cause, your doctor can help you get the treatment to get things moving through your system again.