Cathartics, or laxatives, are substances that accelerate the bowel evacuation process in the presence of constipation. Laxatives produce catharsis by increasing bulk, moisture, and intestinal motility. Classifications include bulk-forming, emollients, osmotics, and stimulants. Pharmaceutical companies manufacture over-the-counter and prescription preparations such as capsules, liquids, pills, and powders that mix with liquids. Suppositories are another form of purgative laxative.
A bulk cathartic aids in defecation by introducing fiber into the intestine. The fiber expands with moisture, producing bulk, which pushes stool through the intestine. Fresh fruits and vegetables, along with whole grains are the most recommended ways of adding fiber to the diet. Psyllium is a plant fiber that is often used in the production of over-the-counter fiber laxatives. Manufactured in tablet or powder form, individuals take the substance with a full glass of water, which prevents excess gas formation and possible bowel blockage.
Commonly known as a stool softener, an emollient cathartic coats the lining of the intestines. These oil-based lubricants provide a slick surface through which stools slide easily. The oil coating also keeps moisture in the stool by preventing absorption by the bowel. Extensive use can deplete the body of nutrients or of the benefits of certain medications as the coated bowel has decreased absorption capability. Docusate sodium and mineral oil are common over-the-counter emollients.
Hard stools occur secondary to a lack of fluid in the bowel, which an osmotic cathartic corrects. This type of laxative contains magnesium citrate, sodium sulfate, or other minerals that draw fluid from intestinal tissue back into the stool through the process of osmosis. The rehydrated stool becomes softer and easier to eliminate. These substances also require that individuals who take them drink adequate amounts of fluid, which supplies hydration to bowel tissues. Taking the laxative with fluid also prevents abdominal cramping and flatulence.
Under normal conditions, the lining of the bowel creates wave-like movements by contracting muscles, which push the stool toward evacuation. Under certain circumstances, that may include severe constipation or surgical procedures, the movement, also called peristalsis, ceases. A stimulant cathartic reactivates this peristaltic movement. This is the quickest method for eliminating constipation. Senna, in tablet form is a commonly used stimulant that does not require a prescription.
There are preparations on the market that contain more than one type of cathartic. Some contain stool softeners along with stimulating agents, providing faster relief. Health care providers advise against the regular use of laxatives, as the bowel may cease to function normally and become dependent. Along with consuming adequate amounts of dietary fiber and fluids, physicians also recommend that people get plenty of physical exercise.