Table of Contents
- Constipation definition and facts
- What is constipation?
- What causes constipation?
- Medications that cause constipation
- Other causes of constipation
- What are constipation symptoms?
- What tests help diagnose the cause of severe constipation?
- How are the causes of constipation treated?
- Dietary fiber, bulk-forming and lubricant laxatives, and stool softeners
- Over-the-counter (OTC) laxatives
- Biofeedback, exercise, and surgery
- Prescription drugs to treat constipation
- Home remedies for constipation relief
- When should I seek medical care for chronic constipation?
- What is new in the treatment of constipation?
Quick Guide19 Constipation Myths and Facts
Over-the-counter (OTC) laxatives
Saline laxatives contain non-absorbable ions such as magnesium, sulfate, phosphate, and citrate [for example, magnesium citrate (Citroma), magnesium hydroxide, sodium phosphate). These ions remain in the colon and cause water to be drawn into the colon. Again, the effect is soften feces.
Magnesium also may have mild stimulatory effects on the colonic muscles. The magnesium in magnesium-containing products is partially absorbed from the intestine and into the body. Magnesium is eliminated from the body by the kidneys. Therefore, patients with impaired kidney function may develop toxic levels of magnesium from chronic (long duration) use of magnesium-containing products.
Saline laxatives act within a few hours. In general, potent saline products should not be used on a regular basis. If major diarrhea develops with the use of saline products and the lost fluid is not replaced by the consumption of liquids, dehydration may result. The most frequently-used and mildest of the saline products is milk of magnesia. Epsom Salt is a more potent saline laxative that contains magnesium sulfate.
Stimulant laxatives cause the muscles of the small intestine and colon to propel their contents more rapidly. They also increase the amount of water in it, either by reducing the absorption of the water in the colon or by causing active secretion of water in the small intestine.3
The most commonly-used stimulant products contain cascara (castor oil), senna (for example, Ex-Lax, Senokot), and aloe. Stimulant products are very effective, but they can cause severe diarrhea with resulting dehydration and loss of electrolytes (especially potassium). They also are more likely than other types of laxatives to cause intestinal cramping. There is concern that chronic use of stimulant laxatives may damage the colon and worsen the condition, as previously discussed. Bisacodyl (for example, Dulcolax, Correctol) is a stimulant laxative that affects the nerves of the colon which, in turn, stimulate the muscles of the colon to propel its contents. Prunes also contain a mild colonic stimulant.
There are many different types of enemas. By distending the rectum, all enemas (even the simplest type, the tap water enema) stimulate the colon to contract and eliminate the material. Other types of enemas have additional mechanisms of action. For example, saline enemas cause water to be drawn into the colon. Phosphate enemas (for example, Fleet phosphosoda) stimulate the muscles of the colon. Mineral oil enemas lubricate and soften hard stool. Emollient enemas (for example, Colace, Microenema) contain agents that soften it.
Enemas are particularly useful when there is impaction, which it hardens in the rectum. In order to be effective, the instructions that come with the enema must be followed. This requires full application of the enema, appropriate positioning after the enema is instilled, and retention of the enema until cramps are felt. Defecation usually occurs between a few minutes and one hour after the enema is inserted.
Enemas are meant for occasional rather than regular use. The frequent use of enemas can cause disturbances of fluids and electrolytes in the body. This is especially true of tap water enemas. Soapsuds enemas are not recommended because they can seriously damage the rectum.
As is the case with enemas, different types of suppositories have different mechanisms of action. There are stimulant suppositories containing bisacodyl (for example, Dulcolax). Glycerin suppositories are believed to have their effect by irritating the rectum. The insertion of the finger into the rectum when the suppository is placed may itself stimulate a bowel movement.
There are many products that combine different laxatives. For example, there are oral products that combine senna and psyllium (Perdiem), senna and docusate (Senokot-S), and senna and glycerin (Fletcher's Castoria). One product even combines three laxatives, senna-like casanthranol, docusate, and glycerin (Sof-lax Overnight). These products may be convenient and effective, but they also contain stimulant products. Therefore, there is concern about permanent colonic damage with the use of these products, and they probably should not be used for long-term treatment unless non-stimulant treatment fails.
Biofeedback, exercise, and surgery
Most of the muscles of the pelvis surrounding the anus and rectum are under some degree of voluntary control. Thus, biofeedback training can teach patients with pelvic floor dysfunction how to make their muscles work more normally and improve their ability to defecate. During ano-rectal biofeedback training, a pressure-sensing catheter is placed through the anus and into the rectum. Each time a patient contracts the muscles, the muscles generate a pressure that is sensed by the catheter and recorded on a screen. By watching the pressures on the screen and attempting to modify them, patients learn how to relax and contract the muscles more normally.
People who lead sedentary lives are more frequently constipated than people who are active. Nevertheless, limited studies of exercise on bowel habit have shown that exercise has minimal or no effect on the frequency of how often you go to the bathroom. Thus, exercise can be recommended mostly for its many other health benefits, but not for its effect on constipation.
For patients with problematic constipation that is due to diseases of the colon or laxative abuse, surgery is the ultimate treatment. During surgery, most of the colon, except for the rectum (or the rectum and part of the sigmoid colon), is removed. The cut end of the small intestine is attached to the remaining rectum or sigmoid colon. In patients with colonic inertia, surgery is reserved for those who do not respond to all other therapies. If the surgery is to be done, there must be no disease of the small intestinal muscles. Normal small intestinal muscles are evidenced by normal motility studies of the small intestine itself.
Electrical pacing is still in its experimental phases. Electrical pacing may be done using electrodes implanted into the muscular wall of the colon. The electrodes exit the colon and are attached to an electrical stimulator. Alternatively, stimulation of the sacral skin can be used to stimulate nerves going to the colon. These techniques are promising, but much more work lies ahead before their role in treating the condition, if any, has been defined.
Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.
National Institutes of Diabetes and Digestive and Kidney Diseases. "Constipation."
National Institute of Diabetes and Digestive and Kidney Diseases. "Eating, Diet, & Nutrition for Constipation.