What Causes Constipation?

Medically reviewed by Judith Marcin, MD on October 10, 2016 Written by Danielle Moores

According to the National Institute of Diabetes and Digestive and Kidney Diseases, constipation is one of the most common digestive problems in the United States, affecting around 42 million Americans. Constipation is defined as having hard, dry... Read More

According to the National Institute of Diabetes and Digestive and Kidney Diseases, constipation is one of the most common digestive problems in the United States, affecting around 42 million Americans. Constipation is defined as having hard, dry bowel movements, or going fewer than three times a week.

What causes constipation?

Your colon’s main job is to absorb water from residual food as it’s passing through your digestive system. It then creates stool (waste). The colon’s muscles eventually propel the waste out through the rectum to be eliminated. If stool remains in the colon too long, it can become hard and difficult to pass.

Poor diet frequently causes constipation. Dietary fiber and adequate water intake are necessary to help keep stools soft.

Fiber-rich foods are generally made from plants. Fiber comes in soluble and insoluble forms. The soluble fiber can dissolve in water and creates a soft, gel-like material as it passes through the digestive system. Insoluble fiber retains most of its structure as it goes through the digestive system. Both forms of fiber join with stool, increasing its weight and size while also softening it. This makes it easier to pass through the rectum.

Stress, changes in routine, and conditions that slow muscle contractions of the colon or delay your urge to go may also lead to constipation.

Common causes of constipation include:

  • low-fiber diet (particularly diets high in meat, milk, or cheese)
  • dehydration
  • lack of exercise
  • delaying the impulse to have a bowel movement
  • travel or other changes in routine
  • certain medications, such as high calcium antacids and pain medications
  • pregnancy

Underlying medical problems

The following are some underlying medical problems that can bring on constipation:

  • certain diseases, such as stroke, Parkinson’s disease, and diabetes
  • problems with the colon or rectum, including intestinal obstruction, irritable bowel syndrome, or diverticulosis
  • overuse or misuse of laxatives (medications to loosen stools)
  • hormonal problems, including an underactive thyroid gland

What are the symptoms of constipation?

Each person’s definition of “normal” bowel movements may be different. Some individuals go three times a day, while others go three times a week. However, you may be constipated if you experience the following symptoms:

  • fewer than three bowel movements a week
  • passing hard, dry stools
  • straining or pain during bowel movements
  • a feeling of fullness, even after having a bowel movement
  • experiencing a rectal blockage

Who is at risk for constipation?

Eating a poor diet and not exercising are major risk factors for constipation. You may also be at greater risk if you are:

  • Age 65 or older: Older adults tend to be less physically active, have underlying diseases, and eat poorer diets.
  • Confined to bed: Those who have certain medical conditions, such as spinal cord injuries, often have difficulty with bowel movements.
  • A woman or child: Women have more frequent episodes of constipation than men, and children are affected more often than adults.
  • Pregnant: Hormonal changes and pressure on your intestines from your growing baby can lead to constipation.

How is constipation diagnosed?

Many people affected by constipation choose to self-treat by changing their diets, increasing exercise, or using over-the-counter laxatives. However, laxatives should not be used for more than two weeks without consulting a physician. Your body can become dependent on them for colon function.

You should talk to your primary care provider if:

  • you have had constipation for more than three weeks
  • you have blood in your stool
  • you have abdominal pain
  • you are experiencing pain during bowel movements
  • you are losing weight
  • you have sudden changes in your bowel movements

Your doctor will ask questions about your symptoms, medical history, and any medications or underlying conditions. A physical examination may include a rectal exam and blood tests to check your blood count, electrolytes, and thyroid function.

In severe cases, additional tests may be required to identify the cause of your symptoms. Tests may include the following.

An examination of how food is moving through your colon, called a marker study or colorectal transit study. For this test, you will swallow a pill that contains tiny markers that will show up on an X-ray. Numerous abdominal X-rays will be taken over the next few days so the doctor can visualize how the food is moving through your colon and how well your intestinal muscles are working. You may also be asked to eat a diet high in fiber during the test.

An examination of the anal sphincter muscle function, called anorectal manometry. For this test, your doctor will insert a thin tube with a balloon tip into your anus. When the tube is inside, the doctor will inflate the balloon and slowly pull it out. This test allows him or her to measure your anal sphincter’s muscle strength and see if your muscles are contracting properly.

An examination of the colon with a barium enema X-ray. For this test, you will drink a special liquid the night before the test to clean out the bowel. The actual test involves the insertion of a dye called barium into your rectum, using a lubricated tube. The barium highlights the rectum and colon area, allowing the doctor to better view them on an X-ray.

An examination of the colon with a colonoscopy. In this test, your doctor will examine your colon using a tube that is outfitted with a camera and light source (colonoscope). A sedative and pain medication is often given, so you will likely not even remember the examination and should feel no pain. To prepare for this test, you will be on a liquid-only diet for one to three days, and you may have to take a laxative or enema the night before the test to clean out the bowel.

How to treat and prevent constipation

Changing your diet and increasing your physical activity level are the easiest and fastest ways to treat and prevent constipation. Try the following techniques as well:

  • Every day, drink 1.5 to 2 quarts of unsweetened, decaffeinated fluids, like water, to hydrate the body.
  • Limit consumption of alcohol and caffeinated drinks, which cause dehydration.
  • Add fiber-rich foods to your diet, such as raw fruits and vegetables, whole grains, beans, prunes, or bran cereal. Your daily intake of fiber should be between 20 and 35 grams.
  • Cut down on low-fiber foods, such as meat, milk, cheese, and processed foods.
  • Aim for about 150 minutes of moderate exercise every week, with a goal of 30 minutes per day at least five times per week (try walking, swimming, or biking).
  • If you feel the urge to have a bowel movement, don’t delay. The longer you wait, the harder your stool can become.
  • Add fiber supplements to your diet if needed. Just remember to drink plenty of fluids because fluids help fiber work more efficiently.
  • Use laxatives sparingly. Your doctor may prescribe laxatives or enemas for a short period of time to help soften your stools. Never use laxatives for more than two weeks without talking to your doctor. Your body can become dependent on them for proper colon function.
  • Consider adding probiotics to your diet, like those found in yogurt and kefir with live active cultures. Studies have shown that this dietary change can be helpful for those with chronic constipation.

If you still have trouble with constipation, your doctor may prescribe medications to help. According to the American College of Gastroenterology, linaclotide (Linzess) and lubiprostone (Amitiza) are two drugs that are strongly recommended for people with IBS-related constipation. These medications work by increasing the secretions in your intestines, making the stool easier to pass.

Your doctor may also advise that you stop taking certain medications that may cause constipation. More severe colon or rectal problems may require manual procedures to clear the colon of impacted stool, therapy to retrain slow muscles, or surgery to remove the problem part of your colon.

What is the outlook for constipation?

Most cases of constipation are mild and easily treated with changes in diet and exercise. If you are experiencing chronic constipation, or constipation along with other bowel changes, it’s important that you talk to your doctor. 

Medically reviewed by Judith Marcin, MD on October 10, 2016 Written by Danielle Moores

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This feature is for informational purposes only and should not be used to diagnose. Please consult a healthcare professional if you have health concerns.

Medically reviewed by Judith Marcin, MD on October 10, 2016 Written by Danielle Moores