When stool is impacted, tap water enemas are commonly used. Usually people are positioned on their left side, with knees flexed. About 5 to 10 ounces of water, at body temperature, are gently instilled into the rectum and sigmoid colon. When the water is emptied, the impacted stool is passed with it. Non-prescription prepackaged enemas can be used in place of tap water. If enemas fail to work, a health care practitioner may need to remove the stool manually using a gloved finger. The person is then sometimes asked to drink a solution containing dissolved salts and polyethylene glycol, which cleanses the digestive tract.
After the impaction has been removed, the person may be told to add fiber to the diet or to use laxatives to prevent constipation. Laxatives may be used every two to three days if a bowel movement does not occur naturally.
If the stool is not impacted, several options are available for treating constipation. Increasing the intake of fluids and fiber is often the first step. Vegetables, fruit (especially prunes), whole-grain breads, and high-fiber cereals are excellent sources of fiber. Bran is an alternative source, although it may cause excessive gas and bloating. To work well, fiber should be consumed with plenty of fluids.
Laxatives and stool softeners are sometimes needed if changes in diet are insufficient. Most laxatives are safe for long-term uses, if used appropriately.
Bulking agents, such as psyllium and methylcellulose, are laxatives that help hold water in the stool and add bulk to it. The increased bulk stimulates the natural contractions of the large intestine. Bulkier stools are softer and easier to pass. Bulking agents act slowly and gently. These agents generally are taken in small amounts at first. The dose is increased gradually until regularity is achieved.
Osmotic agents are laxatives that keep large amounts of water in the large intestine, making the stool soft and loose. These laxatives consist of salts or sugars that are poorly absorbed. Some contain magnesium and phosphate, which can be partially absorbed resulting in harm to people with kidney failure.
Stimulant laxatives contain substances that directly stimulate the walls of the large intestine (such as senna and bisacodyl), causing them to contract. Taken by mouth, stimulant laxatives generally cause a bowel movement in six to eight hours. Some are available as suppositories. When taken as suppositories, these laxatives often work in 15 to 60 minutes. Stimulant laxatives are best used for brief periods. If longer use is needed, they may be used daily or every other day, and optimally under a doctor's supervision.
Newer medications, which increase secretion of fluids into the intestine, are available only by prescription. They should be considered if constipation does not respond well to over-the-counter laxatives. When constipation is due to opiate drugs used to treat severe pain, new agents that block the effects of opiates on the gut sometimes can help. Occasionally, a problem with coordination of pelvic floor and anorectal muscles may be identified. This can be treated with biofeedback or muscle retraining exercises; such treatments are performed only in centers which specialize in this area and upon referral by a doctor.