INTRODUCTION
Constipation is the most common complaint that people have about their digestive system. Each year more than 2.5 million Americans visit their healthcare provider for relief from this problem.
Constipation refers to a disturbance in bowel habits, but it has varied meanings. Stools may be too hard or too small, difficult to pass, or infrequent. Infrequent may be defined as fewer than three spontaneous bowel movements per week. However, the frequent need to strain and a sense that the bowels are not empty after a movement are also acceptable definitions of constipation.
CAUSES
Many factors can contribute to or cause constipation, although in most people no single cause can be found. In general, constipation occurs more frequently as people get older. As many as one-third of all individuals over the age of 65 suffer from constipation. There may be several reasons for this; older people may:
- Have a diet low in fiber
- Eat too few calories
- Have decreased activity
- Use medications that can cause constipation
Many medical conditions can also cause constipation. Examples include hypothyroidism (an underactive thyroid), pregnancy, irritable bowel syndrome, diabetes, multiple sclerosis, Parkinson's disease, spinal cord injuries, and colon cancer. In addition, medications used for pain, muscle spasms, depression, mineral deficiencies, high blood pressure, and heart disease can often be associated with constipation. (
See "Patient information: Hypothyroidism"
and
see "Patient information: Screening for colon cancer"
and
see "Patient information: Irritable bowel syndrome"
).
DIAGNOSIS
Initially, a clinician will want to know about a person's bowel habits and the duration of constipation. In many cases, a diary of stool frequency and description is helpful. It is important to discuss any medications that are taken regularly since some can cause constipation (
show table 1
).
A clinician may need to perform a rectal examination as part of the physical examination. A rectal examination involves inserting a gloved finger inside the rectum to feel for any lumps or abnormalities. This test can also check for blood in the stool.
Diagnostic testing may be ordered in some situations. These include a recent change in bowel habits, blood in the stool, weight loss, or a family history of colon cancer. Testing can include blood tests, x-rays, sigmoidoscopy, colonoscopy, barium enema, or more specialized testing if needed. (
See "Patient information: Flexible sigmoidoscopy"
and
see "Patient information: Colonoscopy"
).
COMPLICATIONS
Constipation is uncomfortable and can interfere with a person's quality of life. In addition, chronic constipation can be associated with other problems, including:
TREATMENT
The most important issues for treating constipation include understanding normal bowel function, eating foods high in fiber, and using laxatives or enemas in an appropriate fashion.
Behavior changes
The bowels are most active following meals, and this is often the time when stools will pass most readily. When a person ignores his or her body's signals to defecate, the signals become weaker and weaker over time. By paying close attention to these signals, a person may defecate more easily.
Diet
Eating a diet high in fiber is important. The recommended amount of dietary fiber is 20 to 35 grams of fiber per day. Many breakfast cereals are an excellent source of dietary fiber. By reading the product information panel on the side of the package, it is possible to determine the number of grams of fiber per serving (
show figure 2
). Many different fruits and vegetables can be particularly helpful in preventing and treating constipation (
show table 2A-2C
). This is especially true of citrus fruits, prunes, and prune juice.
For those who do not like high-fiber foods such as fruits, vegetables, and whole grains, psyllium powder mixed in an 8-ounce glass of water or another beverage one to three times daily may be tried. However, consuming large amounts of fiber can cause abdominal bloating or gas; this can be minimized by starting with a small amount and slowly increasing until stools become softer and more frequent.
In addition, a number of other fiber supplements are available to increase fiber intake. Examples include methylcellulose, guar gum, and calcium polycarbophil (
see "Bulk forming" below
). The dose of fiber supplements should be increased slowly to prevent gas and cramping, and they should always be taken with an extra glass of fluid.
Drinking a caffeine-containing beverage in the morning may be helpful for stimulating bowel action.
LAXATIVES
A variety of drugs and natural products are available for treating constipation. Because of the large number of options, most have not been directly compared in clinical studies. Thus, the choice between them is based upon their mechanism of action, safety, and experience.
In general, laxatives can be categorized into the following groups: (
show table 3
).
Bulk forming
These include natural fiber and commercial fiber preparations such as:
- Psyllium (Konsylÿ; Metamucilÿ; Perdiemÿ)
- Methylcellulose (Citrucelÿ)
- Calcium polycarbophil (FiberConÿ; Fiber-Laxÿ; Mitrolanÿ).
These work by increasing the water content and bulk of stool, which tends to decrease the time needed to pass through the colon.
Hyperosmolar
Hyperosmolar laxatives include:
- Polyethylene glycol (MiraLaxÿ, Glycolaxÿ)
These reduce water absorption from the colon, thereby wetting the stool. Stools usually become soft, but they are still formed. Lactulose and sorbitol are also digested by bacteria in the colon, which can produce gas and bloating. Sorbitol works as well as lactulose and is much less expensive. Polyethylene glycol is generally preferred since it does not cause gas or bloating and is available in the United States without a prescription.
Saline laxatives
Saline laxatives such as magnesium hydroxide (Milk of Magnesiaÿ) and magnesium citrate (Evac-Q-Magÿ) act similarly to the hyperosmolar laxatives (ie, they draw water into the colon).
Stimulant laxatives
Stimulant laxatives include senna (eg, Black Draught, ex-laxÿ, Fletcher'sÿ Castoriaÿ, Senokotÿ) and bisacodyl (eg, Correctolÿ, Doxidanÿ, Dulcolaxÿ).
Because of their effectiveness, stimulant laxatives can be overused. Excessive use of stimulant laxatives may be associated with side effects, including low potassium levels. Thus, these drugs should be used with caution if taken regularly. There is no convincing evidence that chronic use of stimulant laxatives causes structural or functional impairment of the colon, nor do they increase the risk for colorectal cancer or other tumors.
New treatments
Tegaserod (Zelnormÿ) is a prescription medication for chronic constipation. It was taken off the market in the United States in March 2007 due to concerns about an increased risk of heart attack, stroke, and severe chest pain.
Lubiprostone (Amitizaÿ) is available for treatment of severe constipation in patients who have not responded to other treatments. It is a medication that increases intestinal fluid secretion. It is expensive compared to other agents but may be recommended if response to other medications or treatments is unsatisfactory.
Treatments to avoid
- Emollients Emollient laxatives, principally mineral oil, soften stools by moisturizing them. They can be used as enemas in patients who have become impacted with stool. Oral use of mineral oil is not recommended, especially in the elderly and other patients with swallowing difficulties; if it is accidentally inhaled into the lungs it can cause pneumonia. In addition, it can cause anal leakage of stool. Alternatives to mineral oil have fewer risks and equal benefit.
- Stool softeners Agents containing docusate (eg, Colaceÿ) were previously thought to increase the fluid content of the stool, making it easier to pass. However, studies have subsequently shown that they are not effective in patients with constipation.
- Natural products A wide variety of natural products have been used for treating constipation. Some of them contain the active ingredients found in commercially available laxatives. However, their dose and purity may not be carefully controlled. Thus, these products are not generally recommended.
A variety of home-made enema preparations have been used throughout the years, such as soapsuds, hydrogen peroxide, and household detergents. These can be extremely irritating to the lining of the intestine and should not be used.
Pills, suppositories, or enemas
Laxative preparations are available as pills that are taken by mouth or as suppositories or enemas that are inserted into the rectum. In general, suppositories and enemas work more quickly compared to pills, but many people do not like using them.
Healthcare providers occasionally recommend tap water enemas every three to four days in patients who have not responded to oral laxatives. However, this can cause excessive absorption of water, potentially leading to dangerous levels of salt in the bloodstream. Small-volume prepackaged enema kits containing sodium phosphate/biphosphate (Fleetsÿ) are convenient and safe when used as directed. These are not recommended for patients who have problems with their heart or kidneys.
BIOFEEDBACK
Biofeedback is a behavioral approach that can be used by some patients with severe chronic constipation. During defecation, the muscles of the pelvic floor and external anal sphincter should relax as a person bears down. Biofeedback can be helpful in treating patients who involuntarily contract (rather than relax) these muscles (referred to as dyssynergic defecation)
A visual monitor is used to measure external anal sphincter pressures while bearing down. The patient watches the recordings of muscle activity or sphincter pressure responses and is asked to modify inappropriate responses through trial and error. Improvement has been seen in patients with dyssynergic defecation who received biofeedback, and a controlled trial found that it was more effective than laxatives [
1
].
WHEN TO SEEK HELP
Patients with constipation should speak with a healthcare provider about their symptoms, especially if the symptoms:
- Are new (ie, represent a change in your normal pattern)
- Last longer than three weeks
- Are severe
- Associated with any other concerning features such as blood on the toilet paper, weight loss, fevers, or weakness
SUMMARY
- Constipation is the most common complaint that people have about their digestive system. Each year more than 2.5 million Americans visit their healthcare provider for relief from this problem.
- Constipation refers to a disturbance in bowel habits. It may mean that stools are too hard or too small, difficult to pass, or infrequent. Infrequent has been defined as fewer than three spontaneous bowel movements per week.
- Many factors can contribute to or cause constipation, although in most patients no single cause can be found. Contributing factors may include a low fiber diet, inadequate fluid intake, inactivity (especially with disabled or elderly persons), and a number of medical conditions, including hypothyroidism (an underactive thyroid), pregnancy, irritable bowel syndrome, diabetes, multiple sclerosis, Parkinson's disease, spinal cord injuries, and colon cancer. In addition, medications used for pain, muscle spasms, depression, mineral deficiencies, high blood pressure, and heart disease can often be associated with constipation.
- Constipation is uncomfortable and can interfere with a person's quality of life. In addition, chronic constipation can aggravate hemorrhoids, lead to fecal impaction (which can cause abdominal pain, nausea, vomiting, urinary retention, and ulcers in the rectum), or anal fissures (painful tears in the anal canal that can be caused by passing a hard stool).
- Diagnostic testing may be ordered in certain situations. These include a recent change in bowel habits, blood in the stool, weight loss, or a family history of colon cancer. Testing can include blood tests, x-rays, sigmoidoscopy, colonoscopy, barium enema, or more specialized testing if needed.
- Behavior changes and a high fiber diet benefit many patients with constipation. Laxatives should be used when behavior changes and fiber are ineffective.
- Daily polyethylene glycol is recommended for patients who do not tolerate or respond to dietary fiber or fiber supplements.
- Patients who do not respond to polyethylene glycol or sorbitol can use stimulant laxatives such as senna or bisacodyl two to three times per week as long as needed.
- A patient should speak with their healthcare provider about constipation, especially if the symptoms are new (ie, represent a change in your normal pattern), last longer than three weeks, severe, or are associated with any other concerning features such as blood on the toilet paper, weight loss, fevers, or weakness.