Constipation

(Hard Stools, Difficulty Passing Stool)

The Facts

Constipation occurs when stool or waste material moves too slowly through the large intestine. Feces that stay in the bowel too long before elimination become hard and dry. This results in difficult, painful, and infrequent bowel movements. In many cases, constipation is harmless, but it can significantly lower your quality of life. It's not a disease, but it might be a symptom of a disease.

Many people believe they are constipated when they're not, thinking that less than one bowel movement a day is abnormal. In fact, as little as twice a week is fine so long as you go easily when you feel the need. A normal bowel movement, no matter how often, should be soft yet hold its shape and be easy to pass without needing to strain.

The Causes

When food leaves the stomach, it's still a partly digested mush. Your body recuperates valuable fluid from it while it's moved down the colon (large intestine). This transforms it into normal feces. The longer it stays in the colon, the drier it gets. This makes it harder.

Obviously, the quantity also increases if you wait to go to the toilet. A large, hard stool can be painful and difficult to pass. This can make people, especially children, reluctant to go, creating a vicious cycle. It's a common pattern of chronic constipation in children, which often begins when they start school. Many young children avoid school toilets and end up waiting too long.

Chronic constipation can last for months or years. It's usually caused by poor diet, some other disease, or regularly ignoring the urge to go to the toilet. Low-fibre diets and insufficient water intake are common causes of constipation.

While most otherwise healthy people will occasionally experience constipation, certain diseases or conditions can also cause it, such as:

bowel obstructions due to a tumour or benign growth
chronic kidney failure
diabetes
hypothyroidism
irritable bowel syndrome
neurologic disorders such as Parkinson's disease, multiple sclerosis, or spinal cord injury
rectal or colon cancer

Acute constipation starts suddenly and lasts for a few days. It can be caused by a blockage, prolonged inactivity, medication, dehydration, or missing a bowel movement. Pregnant people can develop constipation when the womb presses on the intestine. Sometimes, general anesthesia affects the bowel muscles for a few days after surgery. Lead poisoning and swallowing indigestible objects are other rare causes.

Examples of medications that can provoke acute constipation include:

anticonvulsants used for epilepsy
antidepressants
certain diuretics
heart medications such as calcium-channel blockers
iron supplements
medications for Parkinson’s disease
pain medications such as codeine* and morphine
some cough and cold medications containing dextromethorphan
some antacids

Overuse of laxatives eventually makes the bowels less sensitive to the need to eliminate feces and can cause chronic constipation. The bowels become dependent on laxatives to work, and this can lead to bowel distension and sometimes a condition called melanosis coli.

People who are bedridden can develop severe acute blockages called fecal impaction. The stools may have to be removed by their doctor.

Symptoms And Complications

Symptoms of constipation can include:

a sensation that the bowels haven't completely emptied
bloating of the abdomen, and possibly a "rumbling" noise
gas
indigestion
infrequent bowel movements
loss of appetite
lumpy and hard stools that are difficult to pass
needing to strain to get stool out
pain or pressure in the belly
some bleeding as a result of straining

Constipation can cause complications. Very large, hard stools can stretch the anus, tearing the skin. These anal fissures can be very painful. Occasionally, a really tough bowel movement causes rectal prolapse, in which a small section of intestinal lining pokes out of the anus and has to be pushed back in. Hemorrhoids can also be caused by the chronic pushing of constipation.

If you have experienced constipation lasting longer than 7 days or your constipation has been accompanied by vomiting, blood in the stool, weight loss, a swollen and painful abdomen, fever, or small, pencil-sized stool, seek medical attention.

Making A Diagnosis

If constipation is a problem, see your doctor. A physical exam will show whether there are hard stools in your intestine or any unusual masses in your stomach. This will include a digital rectal exam to check muscle tone.

Your doctor might do a sigmoidoscopy or colonoscopy. This involves using a lighted tube with a camera on the end to look into part or all of the large intestine. A barium enema allows abnormalities of the large intestine to be seen on an X-ray. These procedures require some preparation to empty the bowel so that it can be seen on X-ray.

Treatment And Prevention

Constipation can be treated medically, but lifestyle changes are often very important. The following practices can both treat and prevent constipation:

Do physical exercise to stimulate the movement of waste through your intestines.
Drink at least 8 glasses of fluid each day – water is best.
Increase dietary fibre to about 25 g per day for women and 38 g per day for men by eating whole grains, especially flaxseed, fruits, and vegetables (these add bulk to stools, making them easier to pass)
Lower your consumption of processed foods.
Schedule regular times for toilet use. Try to have a bowel movement at the same time each day (after breakfast, for instance).
Talk to a health care professional if you suspect that your medication is causing constipation.
Use prune juice, stewed prunes, or figs to soften hard stools (increase the amount slowly to reduce the risk of gas).
Go to the washroom when you feel the urge to go.

Medications are usually brought in if changing diet and habits doesn't work. Most laxatives should be used sparingly as needed.

Bulk-forming laxatives add bulk to the stool, stimulating defecation.
Others act by coating the feces with oil, preventing water from being absorbed by the intestine.
Some laxatives, including suppositories, are irritants or stimulants that cause the lining of the intestine to contract, helping to push out the stool.
Some laxatives work by pulling water back into the colon to ease transit.
Enemas can be used to increase the amount of water in your stool, rapidly causing defecation.
Mu-opioid receptor antagonists (e.g., methylnaltrexone, naloxegol) are used for people with opioid-induced constipation that is not controlled by other treatments.

These medications can create dependence, so use them only as needed, as directed by your health care professional.

*All medications have both common (generic) and brand names. The brand name is what a specific manufacturer calls the product (e.g., Tylenol®). The common name is the medical name for the medication (e.g., acetaminophen). A medication may have many brand names, but only one common name. This article lists medications by their common names. For information on a given medication, check our Drug Information database. For more information on brand names, speak with your doctor or pharmacist.