The failure to have regular and satisfactory bowel motions causes a mild poisoning of the system, with certain side-effects (foul tongue, bad breath, headache, lassitude and loss of appetite). The common causes of constipation are: habit; a colon which absorbs water too quickly; a spastic colon (the muscle of which remains in a state of spasm); lack of tone of the colon muscle (sometimes because of too little vitamin B in the diet); a diet which has not enough 'roughage' in it to stimulate the intestine to activity; low fluid intake; drug therapy; lack of exercise; or constant neglect to respond to the sensation in the rectum which indicates that it is full and needs emptying (which leads to retention of faeces which then become dry and hard). The condition may be aggravated by the use of purgatives.
In Chinese medicine, infrequent, dry or hard stools usually signify an excess of heat, but may also signify deficient fluids or deficient qi.
Over-the-counter (OTC) sales of laxatives generate $400 million annually in the United States. Because approximately 30% of healthy elderly people use laxatives regularly, the elderly contribute substantially to this $400 million market. Indeed, laxatives are second only to analgesics as the OTC medications most widely used by the elderly. Many of these people do not regard themselves as constipated, but simply in need of a regular purgative. Many of those people who do regard themselves as constipated do not have true constipation (defined as fewer than three bowel movements a week, straining at stool, or both).