Bulk-forming laxatives increase the size and softness of stools. Bulkier stools trigger bowel contractions, and softer stools are easier to pass. Bulk-forming laxatives have this effect because they contain a form of fiber that absorbs water as it passes through the digestive tract. You might be able to use bulk-forming laxatives to treat constipation or diarrhea, though you should discuss your digestive problems with your doctor before attempting to treat them yourself.
Forms
Bulk-forming laxatives come in many forms, including liquid, granule, powder, tablet, delayed-release tablet, chewable tablet, packet, capsule, and wafer forms. Note that bulk-forming laxatives don't affect stools already in your rectum. Instead, they prevent constipation by increasing the size of stools as your body produces them.
Fiber
Different brands of bulk-forming laxatives use different types of fiber to absorb water and increase the size of stools. Types of fiber include psyllium, methylcellulose, polycarbophil, cellulose and plantago. If your doctor suggests a particular type of fiber, ask for a brand-name recommendation or check the labels of products to determine which type of fiber they contain.
Types
Failure to take a bulk-forming laxative with sufficient liquid can lead to a blockage in your intestinal tract. Follow the directions supplied by the manufacturer. Typically, each dose should be accompanied by 8 oz. of liquid, such as water or fruit juice, according to the University of Maryland Medical Center.
Comparisons
Bulk-forming laxatives typically are considered the gentlest because they add fiber to the diet to increase the size of stools. Other forms of laxatives use different methods to relieve constipation. Lubricant laxatives coat the surface of stools so they retain water. Saline laxatives pull fluids into the bowel from surrounding tissue. Stool softeners help mix fluids into stools. Finally, stimulant laxatives initiate bowel contractions to push stools out. Your body can develop a dependence on stimulant laxatives, so you shouldn't use them for more than a few days.
