Laxative ingredients are divided into two categories: stimulating and nonstimulating. The stimulating herbs cascara sagrada and senna are "very effective cleansing agents," says Meghan Lake, research and technical marketing associate with Nature's Secret, which uses cascara sagrada in its whole-body cleanses. Stimulant herbs work by irritating the digestive walls, causing them to release whatever's stuck to them in a watery blast. They can be effective for people with severe constipation or those who want a thorough cleanse, Lake says.

The alternative is magnesium citrate or magnesium hydroxide, also known as milk of magnesia. These nonstimulating minerals work as osmotic laxatives, pulling water into the intestine and softening the stool. They don't deliver explosive results, but they do avoid the cramping associated with cascara sagrada and senna, says Cheryl Myers, vice president of health sciences for Enzymatic Therapy, which makes a variety of nonstimulant cleanses.

Erika Horowitz, N.D., says nonstimulant laxatives aren't as habit-forming as the stimulants. To avoid laxative dependence or too much intestinal irritation, Nature's Secret recommends using its cascara cleanses for a maximum of 30 days at a time.