Constipation is a symptom for which treatment is often provided on the basis of a patient’s subjective interpretation that there is a disturbance in bowel function. Not unexpectedly, the definition of constipation has different meanings for different persons. Many physicians define constipation as a stool frequency consistently less than three per week. This is based on epidemiological studies that indicate that 98% of adults in the United States or the United Kingdom have stool frequencies of three per week or greater. Self-reported constipation in the United States is more prevalent in women, non-whites, and those over age 60. After adjusting for these factors, constipation is more prevalent in those with little daily activity or exercise, low income, and poor education. The prevalence of constipation in multiple sclerosis is high and may be worsened by physical inactivity or use of medications with constipating side effects.