Senna, or Cassia senna, is a shrub-like plant native to northern Africa. Both Western and Eastern herbal traditions use its leaves and pods for their laxative effects. Senna is available in tablets, capsules or teas. Some controversy surrounds senna's possible adverse effects. Consult your doctor for guidance on proper dosing and appropriate use of senna.
LAXATIVE
Senna contains active compounds that have two primary laxative effects. They cause the normal absorption of water from your colon to reverse, adding fluid to the contents of your colon. Anthranoids also increase contractions of the colon wall, according to Dr. Holly Phaneuf, author of "Herbs Demystified: A Scientist Explains How the Most Common Herbal Remedies Really Work." Together, these effects promote rapid elimination.
WATER LOSS
Senna remains inactive in your system until bacteria in your colon activate it. The interaction between these active molecules, called sennosides, and the cells that line your colon wall results in the release of prostaglandins and nitric oxide, which stimulate peristalsis, the rhythmic contractions that move intestinal contents along and move water into the colon. Because senna promotes water loss, taking too much can cause diarrhea, dehydration and electrolyte imbalances. Consult your doctor for proper dosing and supervision when using senna, and always drink plenty of water to replace fluid loss when using this herb.
LONG-TERM EFFECTS
If you suffer from chronic constipation, senna may help improve that condition. Use senna for up to a week at a time. With long-term use at high doses -- those that induce diarrhea -- you may develop a tolerance to senna that results in its diminished effectiveness. Your healthiest option is to consume a healthy diet, high in soluble and insoluble fiber, along with plenty of pure water and fruits, vegetables, soups and other high-water-content foods and use senna sporadically, as needed.
ADVERSE EFFECTS
Senna is a strong laxative and can cause painful cramping and diarrhea. Senna can cause severe adverse reactions in children, including blisters, rashes and diarrhea. Pregnant women should not take senna, as it may cross the placental barrier and cause cramping in the fetus. Senna's active compounds also cause your colon wall to become pigmented. This effect is benign and fully reversible when you stop using senna.
ANTIMICROBIAL
In addition to its laxative effects, senna may provide antibacterial and antiviral benefits. Senna contains anthraquinone and other antioxidants and may be useful for lowering cholesterol and triglycerides. A study published in the January issue of "Natural Product Research" found flavonoid antioxidants with pronounced antioxidant activity in extracts of a species of Senna known as Senna macranthera.