How Do Tea Laxatives Work?

Constipation is one of the most common digestive complaints in the United States, affecting approximately 15 percent of the population. Each year, Americans spend more than $700 million on laxative products -- the most common form of self-treatment -- to try to get things moving. One of these products is laxative tea, which usually contains senna as an active ingredient.

A woman is holding a tea cup. (Image: Sam Royds/Photodisc/Getty Images)

The Active Ingredient

Senna, which contains sennosides, is extracted from the senna plant. Because of the way it works on the bowels, senna is classified as a stimulant laxative. Stimulant laxatives stimulate the nerve plexus in the intestinal wall, causing the muscles to squeeze and contract to move stool out. Specifically, the sennosides in senna irritate the lining of the bowel, resulting in a laxative effect.

Dosage Recommendations

Stimulant laxatives like senna generally produce a bowel movement in six to 10 hours. Because of the way stimulant laxatives work, there is generally sense of urgency to the bowel movement. The typical dose is 15 milligrams to 30 milligrams twice per day, and it is only recommended for short-term use -- a period of five to seven days.

Some Words of Caution

When used as directed, the side effects of laxative tea are generally mild. The most common side effects include stomach cramps, diarrhea and discomfort. Tea laxatives are not recommended for long-term use. Using senna for more than two weeks can cause structural or muscular changes to the colon -- a condition known as lax colon. When the colon becomes lax, it stops functioning normally and having a bowel movement without a laxative becomes more difficult. Long-term use of laxative teas that contain senna can also lead to electrolyte imbalances, which are associated with muscle weakness, liver damage and heart function disorders.

Other Laxative Herbs

Laxative teas may also contain other stimulant laxative herbs, such as aloe, buckthorn, black root, blue flag and rhubarb, that work on the colon in the same way that senna does. Teas that contain several stimulant laxative herbs increase the chance of experiencing a drop in potassium levels. Low potassium levels can disrupt heart rhythm and, in severe cases, lead to heart attack. Use extra caution when drinking teas that contain a combination of herbs or in using laxative herbs together.